Patent Publication Number: US-2023160586-A1

Title: Ionizer Feedback Control

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a Continuation In Part of U.S. Pat. Application Serial No. 17/527,115 filed on Nov. 15, 2021, and U.S. Pat. Application Serial No. 17/244,389 filed on Apr. 29, 2021 and issued as U.S. Pat. 11,173,226 issued on Nov. 16, 2021, which applications are incorporated by reference in their entirely. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to the field of air treatment, and more particularly to apparatus and methods for an ionizer. Examples include applications to improve indoor air quality in buildings, automobiles, airplanes, trains, boats, transportation systems, refrigeration systems, or enclosed environments with Heating, Ventilating, Air Conditioning (HVAC) systems. 
     BACKGROUND OF THE INVENTION 
     Known ionizers are generally installed at an inlet of a fan installed on a Heating, Ventilating, Air Conditioning (HVAC) system. Ionizers may also be installed on a fan motor or a fan blade or inside an air duct or on the inlet of a fan of an air cleaner. Known ionizers are used to produce high concentrations of positive and/or negative ions which attach to particles in a volume of air or particles in an airflow volume causing said particles to become positively and/or negatively charged and combine with other particles which become larger and heavier. Clusters of larger and heavier particles are removed from the air by air filters or removed from the air by being attracted to surfaces in a duct system or surfaces inside a building. Ions are also attracted to virus, bacteria, mold, and other airborne pathogenic microbes. When ions combine on the surface of a pathogen, a chemical reaction occurs on the cell surface membrane which produces hydroxide (OH+ or OH-) radicals which removes a hydrogen atom (H) from the pathogen. This chemical reaction severs a protein on the cell membrane which deactivates or destroys the pathogen. The ionized OH radicals bond with the removed hydrogen and form water vapor (H2O). Ionization kills pathogens without damaging the DNA in the interior cells of the pathogen, so it does not cause cancer. Ionization may partially or fully break down Volatile Organic Compound (VOC) hydrocarbon chains into harmless compounds such as oxygen, nitrogen, water vapor, and carbon dioxide. Ionization also removes dust and odors. 
     The California Air Resources Board (CARB) adopted a regulation to limit ozone emissions from indoor air cleaning devices (AB 2276). Since 2010, all indoor air cleaners sold in, or shipped to, California must meet ozone emission and electrical safety standards and produce a Time Weighted Average (TWA) ozone concentration less than 0.050 parts per million by volume (ppmv) over 8 hours when tested in a 30 meter cubed (m3) chamber. https://ww2.arb.ca.gov/sites/default/files/2017-08/acrfactsheet.pdf https://ww2.arb.ca.gov/sites/default/files/2020-03/air-cleaner-regulation.pdf https://ww2.arb.ca.gov/resources/fact-sheets/californias-regulation-limit-ozone-emissions -indoor-air-cleaning-devices. The United States (US) Food and Drug Administration (FDA) requires ozone output of indoor medical devices to be no more than 0.05 ppmv. See https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=801.415. The US Occupational Safety and Health Administration (OSHA) requires that workers not be exposed to an average concentration of more than 0.10 ppmv for 8 hours. The US Environmental Protection Agency (EPA) ozone standard is a maximum 8 hour average concentration of 0.08 ppmv. See https://www.epa.gov/indoor-air-quality-iaq/ozone-generators-are-sold-air-cleaners#ozone -health. 
     Known ionizers may operate over a range of electrical signal inputs from 20 Volts Alternating Current (VAC) to 30 VAC or line voltages from 120 to 277 VAC. Ionizers for HVAC systems are typically designed to operate at 24 VAC, but HVAC system transformer voltages may vary from 24 to 30 VAC. Known ionizers operating at transformer voltages from 24 to 30 VAC may provide higher ozone concentrations than allowed by the CARB and US FDA. The Underwriters Laboratories (UL) 867 Section 40 ozone concentration tests or the Canadian Standards Association (CSA) 22.2 Num ber 187 in-duct ozone concentration tests are used to certify polar and bipolar ionizers for public safety. These tests might provide false positive results if tests are only performed at a single transformer voltage of 24 VAC. 
     Field tests indicate that some ionizers are sensitive to magnetic fields from rare earth magnets used to attach bipolar ionizers to sheet metal surfaces of HVAC ducts or fan housings. An ionizer with two rare earth magnets installed by the Original Equipment Manufacturer (OEM) caused ion concentrations to be reduced from 50 to 100 million ions per cubic centimeter (ions/cc) to 50 to 100 ions/cc. Lower ion concentration reduces the efficacy of ionizers to remove particles, break down VOCs, and inactivate airborne pathogens. 
     Known prior art ionizers only have one electrical signal input (and a common signal input) which typically requires the ionizer to be energized continuously which will cause dust to accumulate on the electrodes when the fan is turned off. Dust accumulation may require maintenance. Operating a fan continuously to power the ionizer continuously will significantly increase the fan energy use. 
     According to the National Institute of Standards and Technology (NIST) gas phase ion energetics data, the ozone gas ionization energy is 12.53 ± 0.08 electron Volts (eV). See https://webbook.nist.gov/cgi/cbook.cgi?ID=C10028156&amp;Mask=20#lon-Energetics. The threshold high-voltage output is dependent on and may vary based on an ambient air temperature and a relative humidity as well as a distance the positive-ion electrode is from a grounded surface and the distance the positive-ion electrode is from the negative-ion electrode. 
     A 2021 research study by YICHENG ZENG indicates that bipolar ionizers may not fully decompose Volatile Organic Compounds (VOCs). See YICHENG ZENG, et al., Evaluating a commercially available in-duct bipolar ionization device for pollutant removal and potential by product formation, Building and Environment Journal, May 15, 2021, 14 pages, Volume 195. Elsevier Science Direct. Building and Environment. Amsterdam, NL. https://www.sciencedirect.com/science/article/pii/S036013232100158X ZENG page 12 states that both “the laboratory and field data collected herein suggest that other unintended byproduct formation (e.g., of smaller, potentially oxidized VOCs) is likely occurring, with some consistencies observed in both constituent reductions (e.g., xylene, ethylbenzene, and 1,2-dichloroethane) and increases (e.g., acetone, ethanol, and toluene), with some consistencies observed between both the chamber tests and field tests.” ZENG page 12 further indicates that “if the residence time in the ionizing region is insufficient to fully ionize not only the parent VOCs initially in the indoor air, but also the multiple generations of daughter products, then the unintended consequence of ionizers may be to enhance concentrations of smaller, potentially oxidized daughter VOCs.” 
     There are thousands of VOCs, and some VOCs such as formaldehyde, have been recognized as a health risk and have specific guidelines. The United States (US) Occupational Safety and Health Administration (OSHA) regulates formaldehyde as a carcinogen. OSHA has adopted an 8-hour Time Weighted Average (TWA) Permissible Exposure Limit (PEL) for formaldehyde of 0.75 ppmv and an action level of 0.5 ppmv. According to the OSHA Standard Number 1910.1048(n)(1) for formaldehyde, employers shall not expose employees to formaldehyde at or above 0.1 ppmv. The US Department of Housing and Urban Development (HUD) has established an ambient level for formaldehyde of 0.4 ppmv or less for mobile homes. 
     Based on the OSHA 8-hour TWA PEL of 0.75 ppmv and action level of 0.5 ppmv and employee exposure limit of 0.1 ppmv for formaldehyde, the HUD formaldehyde level of 0.4 ppmv for mobile homes, and research findings published by ZENG regarding “unintended consequence of ionizers may be to enhance concentrations of smaller, potentially oxidized daughter VOCs,” an unresolved problem exists regarding bipolar ionizers operating in an airflow where VOCs such as formaldehyde may be present at concentration levels at or above 0.1 ppmv. 
     A 2011 report by SIDHESWARAN, titled “Quantitative Room Temperature Mineralization of Airborne Formaldehyde Using Manganese Oxide Catalysts,” indicated that air filters with manganese oxide catalysts (manganese sulfate or MnSO4 and sodium permanganate or NaMnO4) showed consistent single-pass formaldehyde oxidation efficiency greater than 80% for the synthesized catalysts, which remained active over at least 35 days. Catalysts were prepared by co-precipitation of MnSO4 and NaMnO4 followed by curing at 100, 200 and 400 C. Characterization was performed using X-ray diffractometry (XRD), porosimetry, scanning electron microscopy (SEM), and Inductively Coupled Plasma - Mass Spectrometry (ICP-MS). Diffractograms of samples treated at 100 and 200 C matched those of nsutite and cryptomelane (K(Mn4+,Mn2+)8O16) or manjiroite (Na(Mn4+7Mn3+)O16) structures, with high BET surface area (up to 149 m2/g) and small particle size (&lt; 50 nm), while curing at 400 C yielded pyrolusite with lower effective surface area. The BET or Brunauer, Emmett and Teller theory is used to evaluate gas adsorption expressed in units of area per mass sample (m2/g). Room temperature catalytic oxidation of airborne formaldehyde was studied by supporting the catalyst on a particulate filter media placed in a flow system, under stable upstream formaldehyde concentrations between 30 and 200 parts per billion (ppb). Two different face velocities (v = 0.2 and 50 cm/s) were studied to evaluate the oxidation efficiency under different flow regimes using formaldehyde-enriched laboratory air at 25-30% relative humidity. Results showed consistent single-pass formaldehyde oxidation efficiency greater than 80% for the synthesized catalysts, which remained active over at least 35 days of continuous operation at v = 0.2 cm/s and were able to process up to 400 m3 of air at v = 50 cm/s without appreciable deactivation. Operation under high relative humidity (&gt;90% RH) produced only a small reversible reduction in formaldehyde removal. Most significantly, 100% mineralization yields were verified by quantifying CO2 formation downstream of the catalyst for upstream formaldehyde concentrations as high as 6 ppm and a face velocity of v = 13 cm/s. See M. SIDHESWAREN, H. DETAILLATS, D. SULLIVAN, J. LARSEN, W. FISK, Quantitative Room Temperature Mineralization of Airborne Formaldehyde Using Manganese Oxide Catalysts, June 2011, Pages 29, LBNL-5169E, Lawrence Berkeley National Laboratory, Berkeley, CA USA. https://indoor.lbl.gov/sites/all/files/lbnl-5169e.pdf. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention ionizer provides solutions to the unresolved problems of deactivating pathogens such as the SARS-CoV-2 virus while not producing ozone, and the unintended consequences of enhancing concentrations of smaller, potentially oxidized daughter Volatile Organic Compounds (VOCs) such as formaldehyde (HCHO). Specifically, the present invention comprises a feedback control to provide a consistent Direct Current (DC) high-voltage electrode output over a range of 20 to 30 Volts Alternating Current (VAC) electric signal inputs to provide a consistent negative ion concentration or a consistent bipolar ion concentration to deactivate pathogens and produce zero ozone concentrations. The present invention also comprises a feedback control to provide an unbalanced DC high-voltage output ratio less than 80 percent over a range of 20 to 30 VAC electric signal inputs to provide a balanced bipolar ion concentration ratio greater than 80 percent to deactivate pathogens and produce zero ozone concentrations. The present invention also comprises sensors to monitor VOCs and/or HCHO in the airflow being treated by the ionizer. If the monitored VOC and/or HCHO concentrations are greater than an eight-hour (8-hour) Time Weighted Average (TWA) Permissible Exposure Limit (PEL) for formaldehyde of 0.75 ppmv and an action level of 0.5 parts per million by volume (ppmv) or greater than 0.1 to 0.4 ppmv for VOCs, then the present invention de-energizes or reduces a positive DC high-voltage output and/or a negative DC high-voltage output to stop generating the ion concentration or reduce the ion concentration to avoid producing or enhancing concentrations of smaller, potentially oxidized daughter VOCs or HCHO. The VOC or HCHO sensors may be mounted up or downstream of the bipolar ionizer. An air filter may also be mounted upstream of the ionizer to remove VOCs, HCHO, and PM 2.25. The air filter may comprise at least one air filter selected from the group consisting of: a Minimum Efficiency Reporting Value (MERV) rated air filter with activated carbon, a High Efficiency Particulate Air (HEPA) filter, or the MERV rated air filter with manganese oxide catalysts such as a manganese sulfate or MnSO4 catalyst, a sodium permanganate or NaMnO4 catalyst, and a cryptomelane potassium manganese oxide mineral or K(Mn4+,Mn2+)8O16 catalyst. The air filter may comprise manganese oxide catalysts to remove formaldehyde through catalytic oxidation to the avoid producing concentrations of smaller, potentially oxidized daughter VOCs such as HCHO. 
     The unbalanced DC high-voltage output ratio is equal to a minimum of an absolute value of a negative DC high-voltage output and a positive DC high-voltage output divided by a maximum of the absolute value of the negative DC high-voltage output and the positive DC high-voltage output. The bipolar ion concentration ratio is equal to a minimum of an absolute value of a negative-ion concentration and a positive-ion concentration divided by a maximum of the absolute value of the negative-ion concentration and the positive-ion concentration. 
     Based on tests performed by Intertek, an ISO-certified independent laboratory, the present invention bipolar ionizer provides a 24-hour TWA ozone concentration of 0.0 ppmv in a 30 meter cubed (m3) chamber per Underwriters Laboratories (UL) Standard (STD) 867 (Electrostatic Air Cleaners) and UL STD 2998 Environmental Claim Validation Procedure (ECVP) for Zero Ozone Emissions from Air Cleaners. Zero ozone is significantly less than the California Air Resources Board (CARB) and United States (US) Food and Drug Administration (FDA) ozone exposure limit of 0.05 ppmv for 8 to 24 hours. 
     Some known prior art bipolar ionizers provide ozone concentrations greater than the CARB ozone exposure limit of 0.05 ppmv for 8 to 24 hours due to providing DC high-voltage output ratios greater than or equal to 80 percent and bipolar ion concentration ratios less than or equal to 80 percent. The present invention provides a solution to this unresolved problem by providing feedback control to maintain a consistent unbalanced DC high-voltage less than 80 percent at the positive and negative electrodes and balanced bipolar ion concentrations greater than 80 percent to produce zero ozone concentrations which are significantly less than the CARB and US FDA ozone exposure limit of 0.050 ppmv across a range of transformer voltages from 20 to 30 VAC and line voltages from 120 to 480 VAC. 
     Based on tests performed by Innovative Bioanalysis, the present invention bipolar ionizer deactivates 97.6 percent of an aerosolized sample of the SARS-CoV-2 delta variant virus within 60 minutes where the aerosolized virus sample is introduced into a chamber 20 feet long by 8 feet wide by 8 feet high with the bipolar ionizer installed at the inlet of a fan circulating air in the chamber similar to a typical Heating, Ventilating, Air Conditioning (HVAC) system fan. Innovative Bioanalysis is an independent Class 3 laboratory (College of American Pathologists (CAP) License 8860298, Clinical Laboratory Improvement Amendments (CLIA) License 05D0955926, California State ID CLF 00324630). The present invention may also be installed downstream of an air filter on a fan inlet or a fan outlet of an air purifier, an automobile HVAC system (12VDC), a box fan, or an air circulation system inside a refrigerator. 
     The present invention comprises an apparatus and/or methods to monitor the positive and/or negative DC high-voltage signals on the positive and/or negative electrodes and process at least one feedback signal and calculate and report an ion concentration based on the at least one feedback signal. Apparatus and/or methods are disclosed to monitor concentrations of VOCs and/or HCHO in the airflow being treated by the ionizer. If the monitored VOC and/or HCHO concentrations are greater than a threshold, for example 0.1 to 0.4 ppm, then the present invention de-energizes or adjusts a positive and/or a negative DC high-voltage output to stop generating the ion concentration or adjust the ion concentration to avoid producing potentially multiple generations of daughter products or enhancing concentrations of smaller, potentially oxidized daughter VOCs or HCHO. When the VOC or HCHO concentration drops below the threshold, the method may energize or adjust the positive and/or the negative DC high-voltage output to enable the ionizer to continue generating an ion concentration to treat the air and deactivate pathogens such as viruses, molds, or fungi. 
     The present invention may also provide “soft power cycling” comprising rebooting a microprocessor controlling the ionizer for several minutes or a short period of time (e.g., 1 to 10 minutes) after a fan providing airflow to the ionizer has been operating continuously for more than several hours or a specified time period (e.g., 1 to 10 hours). Soft power cycling will enhance an ionizer lifetime (e.g., an electronic circuit or a microprocessor) and clear accumulated errors in the microprocessor (if present). Soft power cycling avoids hard power cycling which can stress hardware and lead to failures due to repeated inrush currents. The method also turns off the ionizer when the fan is not operating consistent with UL 867 which requires fan operation with ionizer operation. 
     The present invention may provide a method to send data and/or messages to a software application on a computer, a mobile phone, a watch, or other electronic communications technology regarding the DC high-voltage output and ion concentration, the VOC concentration, or the HCHO concentration. The data and/or alarm messages may be sent to a user using at least one communication method selected from the group consisting of: a graphical display, a text message, an email message, an audio communication message, or a wireless communication message. The wireless communication may use a cellular system, a WIFI (wireless fidelity), a Bluetooth (short-range wireless using UHF radio waves in the ISM bands, from 2.402 GHz to 2.480 GHz), a Low-Power Wide-Area Network (LPWAN with data rates from 0.3 kbit/s to 50 kbit/s per channel), or an ultra-low power Long-range Radio (LoRa) or LoRA Wide Area Network (LoRaWAN) communication protocol. 
     The ionizer comprises a signal conditioning element to process an electrical signal input and provide an excitation signal to a step-up transformer which provides an output voltage to positive and/or negative voltage multipliers which provide a positive high-voltage output greater than an absolute value of a negative high-voltage output or vice versa to a positive-ion electrode and/or a negative-ion electrode. The range of electrical signal inputs may be selected from the group consisting of: 20 to 30 Volts Alternating Current (VAC), 110 to 130 VAC, 210 to 250 VAC, 208 to 280 VAC, 2 to 15 Volts Direct Current (VDC), and 20 to 30 VDC. The signal conditioning element may comprise at least one: wire, opto-isolator, diode, Zener diode, resistor, capacitor, a microprocessor (or oscillator “OSC”), Field Effect Transistor (FET), input and/or output feedback circuit, Resistor Divider Network (RDN), operational amplifier (Op Amp), or comparator. The positive and negative voltage multipliers generate a DC high-impedance high-voltage output to the positive or negative electrodes. The positive or negative multipliers are comprised of one or more voltage multiplier stages where each voltage multiplier stage is comprised of two capacitors and two diodes (e.g., “Cockroft-Walton” multiplier). The Positive Voltage Multiplier (PVM) may provide at least one more multiplier stage than the Negative Voltage Multiplier (NVM) or vice versa. One embodiment provides +2.5 +/- 0.6 kilo-Volts (kV) on the positive and -1.7 kV +/- 0.4 kV on the negative-ion electrode or +1.7 kV +/- 0.4 kV on the positive and -2.5 +/- 0.6 kV on the negative-ion electrode. 
     Another embodiment of the ionizer comprises an input voltage feedback circuit and a microprocessor that monitors a step-up transformer DC input voltage and continuously adjusts a frequency and duty cycle of a digital signal to the FET to produce an excitation signal for the step-up transformer to produce an output voltage to the positive and negative voltage multipliers to create the positive and negative high-voltage outputs to the positive and negative-ion electrodes. A duty cycle is a fraction of a period when a signal is active (e.g., 0 to 100 percent). A period is the time it takes for a signal to complete one on-off cycle. The frequency varies from 8 to 12 kiloHertz (kHz) where kHz is a unit of alternating current or electromagnetic (EM) wave frequency equal to one thousand Hertz (1,000 Hz). 
     Another embodiment may include a high-voltage output feedback circuit, an active element, and a microprocessor to continuously adjust the frequency and duty cycle of the digital signal to the FET to produce the excitation signal for the step-up transformer to achieve the positive and negative high-voltage outputs to the positive and negative-ion electrodes. 
     The ionizer is not impacted by the position or polarity of rare earth magnets fastened to the surface of the bipolar ionizer to attach the bipolar ionizer to sheet metal used for the Heating, Ventilating, Air Conditioning (HVAC) duct work or blower fan housings. Another embodiment provides status or fault alarm information using a Light Emitting Diode (LED) or wireless communication. Another embodiment of the balanced bipolar ionizer may include at least one electrical signal input to energize the ionizer by more than one control signal to allow ionizer operation during a thermostat call for cooling or heating without operating a thermostat Fan G signal continuously. This embodiment will save HVAC energy. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The above and other aspects, features and advantages of the ionizer will be more apparent from the following more particular description thereof, presented in conjunction with the following drawings. 
         FIG.  1    shows a first embodiment of the ionizer with a step-up transformer, positive and/or negative voltage multipliers, and a first signal conditioning element using a first wire for a first electrical signal input to a first opto-isolator and a second wire for a second electrical signal input to a second opto-isolator. 
         FIG.  2    shows a second embodiment with two input terminals, two diodes, a capacitor, a resistor, a Zener diode, a microprocessor or oscillator, and a Field Effect Transistor (FET). 
         FIG.  3    shows a third embodiment of the ionizer with a third signal conditioning element with a positive and a negative feedback circuit. 
         FIG.  4    shows a fourth embodiment of the ionizer with a fourth signal conditioning element with an input voltage feedback circuit 
         FIG.  5    shows a fifth embodiment of the ionizer with a fifth signal conditioning element with an Operational Amplifier (Op Amp) feedback circuit. 
         FIG.  6    shows a sixth embodiment of the ionizer with a feedback circuit based on a Field Effect Transistor (FET) attached to the high-voltage output. 
         FIG.  7    shows a seventh embodiment of the ionizer with a seventh signal conditioning element including a comparator feedback circuit. 
         FIG.  8    shows time series measurements of high-voltage output and the sampled bipolar ion concentration versus time for the ionizer. 
         FIG.  9    provides test results for the ionizer with high-voltage output less than 80 percent with produces zero or very low ozone concentrations. 
         FIG.  10    provides test results for a known prior art bipolar ionizer with high-voltage output greater than or equal to 90% which produces high ozone concentrations. 
         FIG.  11    shows an eighth embodiment of the ionizer including sensors to measure Volatile Organic Compounds (VOCs), Formaldehyde (HCHO), and Particulate Matter less than 2.5 micrometers concentration (a PM 2.5). 
         FIG.  12    shows an embodiment comprising: 1) the ionizer, an HVAC system, 3) a thermostat, 4) a 24VAC transformer, 5) an Air Quality Monitor (AQM), 6) a VOC sensor, 7) a HCHO sensor, and 8) a PM 2.5 sensor. 
         FIG.  13    shows an embodiment comprising: 1) the ionizer, 2) the HVAC system, 3) the thermostat, 4) a 24VAC transformer, 5) an Efficient Fan Controller (EFC), and 6) an Air Quality Monitor (AQM) system comprising an ACM and at least one sensor selected from: 7) a VOC sensor, 8) a HCHO sensor, and 9) a PM 2.5 sensor. 
         FIG.  14    shows an embodiment with an AQM system used to control the balanced bipolar ionizer, where the ACM comprises 1) a microprocessor, 2) an Alternating Current/Direct Current (AC/DC) converter, 3) a switch, and at least one sensor selected from the group consisting of: 4) a VOC sensor, 5) a HCHO sensor, and 6) a PM 2.5 sensor. 
         FIG.  15    shows a first method to control the ionizer to maintain a consistent Direct Current (DC) high-voltage output and consistent ion concentration to minimize ozone concentration to zero parts per million by volume (ppmv) over a range of input voltages. 
         FIG.  16    shows a second method to perform a similar control as the first method while also providing a control to de-energize the ionizer based on at least one Indoor Air Quality (IAQ) concentration selected from: a VOC concentration, a HCHO concentration, or a PM 2.5 concentration. 
         FIG.  17    shows a third method for de-energizing the ionizer when the concentration of VOCs or HCHO is above a threshold specification limit. 
         FIG.  18    provides the mathematical relationship between the at least one feedback signal comprising a DC high-voltage positive signal or a DC high-voltage negative signal and a positive or negative ion concentration. 
         FIG.  19    shows at least one air filter and sensors to measure VOCs, formaldehyde, and PM 2.5 (not shown) installed upstream of the ionizer and similar sensors installed downstream of the ionizer and in the conditioned space. 
     
    
    
     Corresponding reference characters indicate corresponding elements throughout the several views of the drawings. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The following description is the best mode presently contemplated of an ionizer with feedback control to provide consistent Direct Current (DC) high-voltage output and consistent ion concentrations to minimize ozone concentration to zero parts per million by volume (ppmv) over a range of input voltages. This description is not to be taken in a limiting sense, but is made merely for the purpose of describing one or more preferred embodiments of the invention. The scope of the invention should be determined with reference to the claims. 
       FIG.  1    shows a first embodiment of the ionizer  301   a  (large dashed line) with a first signal conditioning element  307   a  (small dashed line), a step-up transformer  316 , a Positive Voltage Multiplier  318  (PVM) connected to a positive-ion electrode  322 , and a Negative Voltage Multiplier  320  (NVM) connected to a negative-ion electrode  324 . The first signal conditioning element  307   a  comprises: 1) a first input terminal  303   a  connected to a first opto-isolator  328  connected to the step-up transformer  316 , 2) a second input terminal  303   b  connected to a second opto-isolator  326  connected to the step-up transformer  316 , and 3) an alternative third input terminal  303   c  connected to a wire  305  connected to the step-up transformer  316 . The alternative third input terminal  303   c  is only used for a single input embodiment shown receiving a second fan G signal  404   a  (dash-dot-dot-dash line) or a second hot R signal  400   a  (dash-dot-dash line). 
       FIG.  1    shows a fan G signal  404  connected to the first input terminal  303   a  and a heat W signal  406  connected to the second input terminal  303   b . The opto-isolators allow either the first electrical signal input or the second electrical signal input (e.g., fan G signal  404 , heat W signal  406 ) to energize the ionizer  301   a  without causing a short circuit if both signals are energized simultaneously. A low-voltage alternating current signal on any of the signal input terminals will produce an excitation signal  424   a  to the step-up transformer  316  to generate a step-up transformer output voltage  426 .  FIG.  1    shows the electrical connections from a thermostat  396  to a Heating, Ventilation, Air Conditioning (HVAC) system (HVAC system  398 ), and a 120 Volts Alternating Current (VAC) to a low-voltage 24VAC transformer (hereafter referred to as a 24 VAC transformer  310 ). The transformer may comprise other electrical signal input voltages. The thermostat  396  may include a hot R terminal  380 , an Air Conditioning (AC) Y terminal (AC Y terminal  382 ), a fan G terminal  384 , a heat W terminal  386 , and a COM C terminal (not shown) typically connected to the COM C terminal  388  of the HVAC system  398  (shown as a ground). The HVAC system  398  may include a hot R terminal  380   a , an AC Y terminal  382   a , a fan G terminal  384   a , a heat W terminal  386   a , and a COM C terminal  388 . A hot R signal  400  is shown as a solid line from the hot R terminal  380  of the thermostat  396  to the hot R terminal  380   a  of the HVAC system  398 , and the hot R terminal  380   a  of the HVAC system  398  is connected to the hot R terminal of the 24 VAC transformer  310 . An AC Y signal  402  is shown as a solid line from the AC Y terminal  382  to the AC Y terminal  382   a  of the HVAC system  398 . 
       FIG.  1    shows the step-up transformer output voltage  426  from the step-up transformer  316  is conducted to a positive voltage multiplier  318  and a negative voltage multiplier  320 . The positive voltage multiplier generates a DC high-impedance Positive High-voltage Output (PHO  428 ) on a positive-ion electrode  322 . The negative voltage multiplier generates a DC high-impedance Negative High-voltage Output (NHO  430 ) on a negative-ion electrode  324 . The positive voltage multiplier  318  and the negative voltage multiplier  320  contain an unequal number of multiplier stages to produce a high-voltage output ratio less than 80 percent and a bipolar ion concentration ratio greater than 80 percent. The high-voltage output ratio is equal to a minimum of an absolute value of a negative high-voltage output and a positive high-voltage output, divided by a maximum of the absolute value of the negative high-voltage output and the positive high-voltage output. The bipolar ion concentration ratio is equal to a minimum of an absolute value of a negative-ion concentration and a positive-ion concentration, divided by a maximum of the absolute value of the negative-ion concentration and the positive-ion concentration. High-voltage Output Ratio (HOR) is calculated using Equation 1. 
     
       
         
           
             HOR 
               
             = 
             
               
                 MIN 
                 
                   
                     ABS 
                     
                       
                         NHO 
                       
                     
                     , 
                     PHO 
                   
                 
               
             
               
             / 
               
             
               
                 MAX 
                 
                   
                     ABS 
                     
                       
                         NHO 
                       
                     
                     , 
                     PHO 
                   
                 
               
             
           
         
       
     
      Where, HOR = High-voltage Output Ratio (fraction), 
     MIN = Minimum value,   ABS = absolute value,   MAX = Maximum value,   PHO = Positive High-voltage Output or PHO  428  (DC Volts), and   NHO = Negative High-voltage Output or NHO  430  (DC Volts).   

       FIG.  2    shows a second embodiment of the ionizer  301   b  with a second signal conditioning element  307   b , the step-up transformer  316 , the positive voltage multiplier  318  connected to the positive-ion electrode  322 , and the negative voltage multiplier  320  connected to the negative-ion electrode  324 . The thermostat  396  and the HVAC system  398  have the same terminals and electrical signals shown in  FIG.  1   . The second signal conditioning element  307   b  comprises: 1) a first input terminal  303   a  and a second input terminal  303   b , 2) signal input processing circuit (a first diode  300 , a second diode  302 , a first capacitor  304 , a first resistor  306 , a first Zener diode  308 ), 3) a microprocessor (or an oscillator “OSC”), and a first Field Effect Transistor (FET) (first FET  314 ). If the oscillator is used, then the oscillator may include at least one resistor and at least one capacitor. The first diode  300  and the second diode  302  rectify low-voltage 24VAC signals from the thermostat or 24 VAC transformer and pass a positively rectified signal to the first capacitor  304  which creates the step-up transformer DC input voltage  424  to the step-up transformer  316 . The first resistor  306  limits the current from the step-up transformer DC input voltage  424  that feeds the first Zener diode  308  to create a +5 Volt signal  418  to the microprocessor  312 . The +5 Volt signal  418  may be created using other components or methods. 
       FIG.  2    shows the microprocessor  312  drives the gate of the first FET  314  with a digital signal  421  which may be a 0 Volt signal or a +5 Volt signal that varies in frequency and duty cycle to create the excitation signal  422  to the step-up transformer  316 . When the first FET  314  is driven with a positive digital signal, the first FET  314  is energized and draws current from the step-up transformer DC input voltage  424  through the step-up transformer  316  to create a magnetic field within the core of the step-up transformer  316 . When the first FET  314  is driven with a zero digital signal, the first FET  314  is gated off and the magnetic field in the step-up transformer  316  collapses which generates the step-up transformer output voltage  426 . The step-up transformer output voltage  426  is passed to the positive voltage multiplier  318  and the negative voltage multiplier  320  which contain an unequal number of multiplier stages to produce a high-voltage output ratio less than 80 percent and a bipolar ion concentration ratio greater than 80 percent. 
       FIG.  3    shows a third embodiment of the ionizer  301   c  with a third signal conditioning element  307   c , the step-up transformer  316 , the positive voltage multiplier  318  connected to the positive-ion electrode  322 , and the negative voltage multiplier  320  connected to the negative-ion electrode  324 . The third signal conditioning element  307   c  comprises: 1) a first input terminal  303   a  and a second input terminal  303   b , 2) signal input processing circuit (a first diode  300 , a second diode  302 , a first capacitor  304 , a first resistor  306 , a first Zener diode  308 , a third diode  300   a , a fourth diode  302   a , a second capacitor  304   a , a second resistor  306   a , a second Zener diode  308   a ), 3) a microprocessor  312  that provides a digital signal  421  to a first FET  314  which provides an excitation signal  422  to the step-up transformer  316 , and 4) a positive voltage feedback circuit  330  and a negative voltage feedback circuit  332 . Also shown is a wireless antenna  313  to provide information regarding the status of the balanced bipolar ionizer. The wireless communication may use a cellular system, a WIFI (wireless fidelity) network, a Bluetooth network (short-range wireless using UHF radio waves in the ISM bands, from 2.402 GHz to 2.480 GHz), a Low-Power Wide-Area Network (LPWAN with data rates from 0.3 kbit/s to 50 kbit/s per channel), or an ultra-low power Long-range Radio (LoRa) or LoRA Wide Area Network (LoRaWAN) communication protocol. The positive and negative voltage feedback circuits allow the microprocessor  312  to modulate the frequency and duty cycle of the step-up transformer output voltage  426  to consistently maintain at least one DC high-voltage signal on a negative-ion electrode or a positive-ion electrode to generate a consistent negative or positive ion concentration over a range of electrical signal inputs selected from the group consisting of: 20 to 30 Volts Alternating Current (VAC), 110 to 130 VAC, 210 to 250 VAC, 208 to 280 VAC, 2 to 15 Volts Direct Current (VDC), and 20 to 30 VDC. 
       FIG.  3    shows a first input terminal  303   a  connected to a first diode  300  and a third diode  300   a  and a second input terminal  303   b  connected to a second diode  302 , and a fourth diode  302   a . The first diode  300  is used to rectify a first electrical signal input (e.g., the fan G signal  404 , the heat W signal  406 , or the hot R signal), and pass the positively rectified signals to the first capacitor  304  which creates a DC voltage used as the step-up transformer DC input voltage  424 . The first resistor  306  limits the current from the step-up transformer DC input voltage  424  to the first Zener diode  308  to create a +5 Volt signal  418  to the microprocessor  312 . The +5 volts signal  418  is also used by the positive voltage feedback circuit  330  and the negative voltage feedback circuit  332 . The third diode  300   a  and the fourth diode  302   a  negatively rectify the first electrical signal input and the second electrical signal input and pass the negatively rectified signals to the second capacitor  304   a  which creates a negative DC voltage. The second resistor  306   a  limits the current from the second capacitor  304   a  to the second Zener diode  308   a  to create a -5 Volt signal  420  used by the positive voltage feedback circuit  330  and the negative voltage feedback circuit  332 . 
       FIG.  3    shows the positive voltage feedback circuit  330  and the negative voltage feedback circuit  332  which contain at least one Resistor Divider Network (RDN) and one active element (not shown) to reduce the PHO  428  and NHO  430  to a Positive Low-voltage Feedback Signal (PLFS  432 ) and Negative Low-voltage Feedback Signal (NLFS  434 ). The positive voltage feedback circuit  330  and the negative voltage feedback circuit  332  reduce and convert at least one DC high-voltage signal to at least one feedback signal where the at least one DC high-voltage signal is selected from the group consisting of: a Negative DC High-voltage Signal (NDHS) or NHO  430  on a negative-ion electrode  324  used to generate a negative-ion concentration  530 , and a Positive DC High-voltage Signal (PDHS) or PHO  428  on a positive-ion electrode  322  used to generate a positive-ion concentration  528 . The at least one feedback signal is selected from the group consisting of: the NLFS  434 , and the PLFS  432 . 
     The microprocessor  312  monitors the at least one feedback signal corresponding to the at least one DC high-voltage signal and compares the at least one feedback signal to a first specification to determine whether the at least one feedback signal is within a first specification. The at least one feedback signal is used by the microprocessor  312  to vary a frequency and a duty cycle of a digital signal  421  to a first FET  314  to control an excitation signal  422  for a step-up transformer  316  and modulate the frequency and the duty cycle of a step-up transformer output voltage  426  to consistently maintain the at least one DC high-voltage signal output (NDHS or NHO  430  and PDHS or PHO  428 ) within a second specification to generate a consistent ion concentration over a range of electrical signal inputs. 
     The at least one feedback signal used by the microprocessor  312  is a low-voltage feedback signal (PLFS  432  or NLFS  434  shown in  FIG.  3   ) or a comparator feedback signal (shown in  FIG.  7   ). The PLFS  432  is approximately one one-thousandth of the PDHS or PHO  428  output (1000:1). The NLFS  434  is inverted to a positive signal by the negative voltage feedback circuit  332  and is one one-thousandth of the NDHS or NHO  430  output. The at least one active element processes the PLFS  432  and NLFS  434  from the respective RDN. The active element may be selected from the group consisting of: 1) an operational amplifier (Op Amp) voltage follower (shown in  FIG.  5   ); 2) a second FET voltage follower (shown in  FIG.  6   ); and 3) a comparator (shown in  FIG.  7   ).  FIG.  3    shows a Light Emitting Diode (LED  347 ) which receives the +5 Volt signal  418 . The LED  347  is connected to a LED resistor  349  which is connected to the microprocessor  312 . The LED  347  may provide status information or fault alarm messages. The microprocessor  312  also processes the at least one feedback signal and calculates and reports a bipolar ionizer concentration based on the at least one feedback signal. 
     The first specification for the at least one feedback signal is selected from the group consisting of: (1) an NLFS specification of +1.7 V +/- 0.4 V to +2.5 V +/- 0.6 V for the NLFS  434 , (2) a PLFS specification of +1.7 V +/- 0.4 V to +2.5 V +/- 0.6 V for the PLFS  432 , (3) a Negative Comparator Feedback Signal (NCFS) specification between 0 and 1 where the NCFS is 1 when the NDHS or NHO  430  is less than the second specification and the NCFS is 0 when NDHS or NHO  430  is greater than the second specification, and (4) a Positive Comparator Feedback Signal (PCFS) specification between 0 and 1 where the PCFS is 1 when the PDHS or PHO  428  is greater than the second specification and the PCFS is 0 when the PDHS or PHO  428  is less than the second specification. The second specification for the at least one DC high-voltage signal is selected from the group consisting of: (1) the NDHS or NHO 430 second specification is -2.5 kV +/- 0.6 kV to +1.7 kV +/- 0.4 kV, and (2) the PDHS or PHO 428 second specification is +1.7 kV +/- 0.4 kV to +2.5 kV +/- 0.6 kV. 
       FIG.  4    shows a fourth embodiment of the ionizer  301   d  including: 1) a fourth signal conditioning element  307   d  with an input voltage feedback circuit  334 , 2) the step-up transformer  316 , 3) a positive voltage multiplier  318  connected to a positive-ion electrode  322 , and 4) a negative voltage multiplier  320  connected to a negative-ion electrode  324 . The fourth signal conditioning element  307   d  comprises: 1) a first input terminal  303   a  and a second input terminal  303   b , and 2) signal input processing circuit (diodes, resistors, and capacitors), 3) an input voltage feedback circuit  334 , and 3) the microprocessor  312  provides a digital signal  421  to a first FET  314  which provides an excitation signal  422  to the step-up transformer  316 . Similar to  FIG.  2   , the first diode  300 , the second diode  302 , the first capacitor  304 , and the first Zener diode  308  are used to create the step-up transformer DC input voltage  424  and the +5 Volt signal  418  from a first or a second electrical signal input. A wireless antenna  313  may be used to provide information regarding the status of the ionizer. As the electrical signal input varies from 20VAC to 30VAC, the microprocessor  312  varies the frequency and duty cycle of the digital signal  421  to the first FET  314  and the excitation signal  422  to the step-up transformer  316  which varies the frequency and the duty cycle of the step-up transformer output voltage  426  to produce a high-voltage output ratio less than 80 percent for the PHO  428  and the NHO  430  and a bipolar ion concentration ratio greater than 80 percent from the positive-ion electrode  322  and the negative-ion electrode  324 . The input voltage feedback circuit  334  includes a Resistor Divider Network (RDN) to reduce the step-up transformer DC input voltage  424  to an input voltage feedback signal  436  which varies between 0 and +5 VDC (Volts Direct Current) and is approximately one tenth of the step-up transformer DC input voltage  424 . The input voltage feedback circuit  334  may be as simple as a low-resistance RDN to provide the input voltage feedback signal  436 . Alternatively, the input voltage feedback circuit  334  shown in  FIG.  4    may include a high-resistance RDN which contains at least one active element to process the voltage from the high-resistance RDN. The at least one active element may be selected from the group consisting of: an Operational Amplifier (Op Amp) shown in  FIG.  5   , a second FET shown in  FIG.  6   , and a feedback comparator shown in  FIG.  7   . 
       FIG.  5    shows a fifth embodiment of the ionizer  301   e  including: 1) a fifth signal conditioning element  307   e , 2) the step-up transformer  316 , 3) a positive voltage multiplier  318  connected to a Positive Electrode Resistor (PER  364 ) which is also connected to a positive-ion electrode  322 , and 4) a negative voltage multiplier  320  connected to a Negative Electrode Resistor (NER  365 ) which is also connected to a negative-ion electrode  324 . The PER  364  and the NER  365  are optionally installed as a safety measure to limit the instantaneous current carried by the positive- and the negative-ion electrodes. The fifth signal conditioning element  307   e  includes: 1) a first input terminal  303   a  and a second input terminal  303   b , 2) a signal input processing circuit (diodes, resistors, and capacitors), 3) a microprocessor  312  that provides a digital signal  421  to a first FET  314  which provides an excitation signal  422  to the step-up transformer  316 , and 4) a feedback circuit  361 . The positive voltage multiplier  318  creates the PHO  428  and the negative voltage multiplier  320  creates the NHO  430 . 
       FIG.  5    shows the feedback circuit includes three operational amplifiers (Op Amps) and a positive Resistance Divider Network (positive RDN  341 ) and a negative RDN  343  to provide feedback from the PHO  428  and the NHO  430  for the microprocessor  312  to modulate the frequency and duty cycle of a digital signal  421  to create the excitation signal  422  to the step-up transformer  316  to provide calibrated unbalanced high-voltage outputs to the positive-ion electrode  322  or the negative-ion electrode  324 . The positive RDN  341  is comprised of a positive feedback 100 MΩ resistor  342  a positive feedback 100 KΩ resistor  344  connected in series where 100 MΩ refers to  100  Million Ohms and 100 KΩ refers to  100  thousand Ohms. The positive RDN  341  reduces the PHO  428  by a ratio of 1000:1 to create a High-impedance Positive Voltage (HPV  442 ). The negative RDN  343  is comprised of a negative feedback 100 MΩ resistor  346  and a negative feedback 100KΩ resistor  348  connected in series. The negative RDN  343  reduces the NHO  430  by a ratio of 1000:1 to create a High-impedance Negative Voltage (HNV  444 ). Similar to  FIG.  3   , a step-up transformer DC input voltage  424  and +5 Volt signal  418  are created from a first electrical signal input supplied to the first input terminal  303   a  or the second electrical signal supplied to the second input terminal  303   b . A first Op Amp  336 , a second Op Amp  338 , and a third Op Amp  340  receive supply voltages from the +5 Volt signal  418  and the -5 Volt signal  420 . The Op Amp is an integrated circuit with two inputs and one output to amplify a weak electrical signal or provide an output voltage difference between two inputs. A wireless antenna  313  may be used to provide status or fault alarm information regarding the balanced bipolar ionizer. 
       FIG.  5    shows the PLFS  432  is created by a first Op Amp  336  which follows the HPV  442  from the PHO  428 . The output from the first Op Amp  336  creates the PLFS  432  sampled by the Analog to Digital (A/D) converter in the microprocessor  312 . The first Op Amp  336  draws negligible current and provides a high-input impedance signal to the positive RDN  341  to not interfere with the accuracy of the signal. The second Op Amp  338  creates a low impedance negative voltage signal from the HNV  444  which is inverted to a positive voltage signal by the third Op Amp  340  in series with a first negative feedback 10KΩ resistor  350  and a second negative feedback 10 KΩ resistor  352 . The output from the third Op Amp  340  creates the NLFS  434  sampled by the A/D converter of the microprocessor  312 . Based on the PLFS  432  and/or the NLFS  434  the microprocessor  312  varies the frequency and duty cycle of the digital signal  421  to the first FET  314  to produce a high-voltage output ratio less than 80 percent for the PHO  428  and the NHO  430  and a bipolar ion concentration ratio greater than 80 percent from the positive-ion electrode  322  and the negative-ion electrode  324 . 
       FIG.  5    shows a Positive Electrode Resistor (PER  364 ) connected between the positive voltage multiplier  318  and the positive-ion electrode  322 , and a Negative Electrode Resistor (NER  365 ) connected between the negative voltage multiplier  320  and the negative-ion electrode  324 . The PER  364  and the NER  365  may be optionally installed as a safety measure to limit the instantaneous current carried by the positive-and the negative-ion electrodes. If the PER  364  or the NER  365  are installed, then these resistors may increase the high-voltage output ratio when the high-voltage output ratio is measured at the negative-ion electrode and the positive-ion electrode. 
       FIG.  5    shows the feedback circuit  361  is comprised of a High-voltage Measurement Circuit (HMC  363 ). The HMC  363  comprises the positive RDN  341  and the first Op Amp  336  which may be used to measure the high-voltage output ratio where the positive RDN  341  is connected to the emitting end of the positive-ion electrode  322  or the negative-ion electrode  324  and the output from the first Op Amp  336  is measured by a digital multimeter. The measured voltage will represent the high-voltage output divided by the positive RDN value (e.g., approximately 1001:1). If the positive RDN  341  is connected to the emitting end of the positive-ion electrode  322 , the voltage from the first Op Amp  336  is a positive voltage output. If the positive RDN  341  is connected to the emitting end of the negative-ion electrode  324 , then the voltage output from the first Op Amp  336  is a negative voltage. When measuring the emitting end of the positive-ion electrode  322  with the digital multimeter, the PER  364  would be connected in series with the positive RDN  341 . Likewise the NER  365  would be in series when measuring the negative-ion electrode  324 . This measurement method is used for data shown in  FIG.  8   ,  FIG.  9   , and  FIG.  10   . 
     The PER  364  resistance reduces the measured voltage from the first Op Amp  336  by the ratio of the PER  364  (or the NER  365 ) and the positive feedback 100 MΩ resistor  342  plus the positive feedback 100 KΩ resistor  344  or the negative feedback 100 MΩ resistor  346  plus the negative feedback 100 KΩ resistor  348 . The measured high-voltage output reduction fraction (Vrf) may be calculated using Equation 2: 
     
       
         
           
             Vrf 
             = 
             1 
             − 
             
               
                 PER 364 or NER 365 
               
             
             / 
             RDN1 
           
         
       
     
      Where, Vrf = high-voltage output reduction fraction with PER  364  or NER  365  (fraction), 
     PER 364 = resistance of PER 364 (Ohms),   NER 365 = resistance of NER 365 (Ohms), and   RDN1 = a first RDN1 resistor comprised of a 100MΩ plus 100KΩ resistor or a second RDN2 comprised of a 200MΩ plus 100KΩ resistor.   

     For example, if the PER  364  value is 10 MΩ, then the high-voltage output reduction fraction from the first Op Amp  336  is approximately 90.01% of the actual output of the positive voltage multiplier  318 . If unequal resistance values for the PER  364  and the NER  365  are used, a measurement of the emitting end of the positive-ion electrode  322  compared to the absolute value of a measurement of the emitting end of the negative-ion electrode  324  might produce similar or equal electrode voltages when the absolute value of the electrode voltages might actually be different by 30 to 40 percent. Unequal resistors might be installed between the voltage multipliers and the electrodes for safety or to make it difficult to measure the actual output of the voltage multipliers. The difference in the values of the unequal resistors would not impact the ion generation since the impedance of air is between 1.3 to 3.3 times 10^16 ohms (with ions present) and changes on the order of Mega Ohms (MΩs) between the unequal resistors would be insignificant with respect to the impedance of air (resistance of dry air is infinite with no ions present). 
       FIG.  6    shows a sixth embodiment of the ionizer  301   f  including: 1) a sixth signal conditioning element  307   f , 2) the step-up transformer  316 , 3) a positive voltage multiplier  318  connected to a positive-ion electrode  322 , and 4) a negative voltage multiplier  320  connected to a negative-ion electrode  324 . The sixth signal conditioning element  307   f  comprises: 1) a first input terminal  303   a  and a second input terminal  303   b , 2) signal input processing circuit (a first diode  300 , a second diode  302 , a first capacitor  304 , a first resistor  306 , a first Zener diode  308 ), 3) a microprocessor  312  and a first FET  314 , and 4) a feedback circuit including a second FET  354  and a positive RDN  341 . The feedback circuit provides feedback from the PHO  428  for the microprocessor to modulate a frequency and a duty cycle of a digital signal  421  to a first FET  314  which provides an excitation signal  422  to the step-up transformer  316  which varies the frequency and the duty cycle of the step-up transformer output voltage  426  which provides the calibrated unbalanced high-voltage outputs to the positive-ion electrode  322  or the negative-ion electrode  324 . A wireless antenna  313  may be used to provide performance information to a software application about the ionizer such as the DC high-voltage signals, the ion concentrations, or electrical faults. 
       FIG.  6    shows the same signal input processing circuit shown in  FIG.  2    to create the step-up transformer DC input voltage  424  and the +5 Volt signal  418  from an electrical power signal. Similar to  FIG.  5   , the positive RDN  341  is comprised of a positive feedback 100 MΩ resistor  342  and a positive feedback 100 KΩ resistor  344  connected in series. The positive RDN  341  reduces the PHO  428  by a ratio of 1000:1 to create the HPV  442 . The output from positive RDN  341  is connected to the gate of the second FET  354 . The second FET  354  is connected in a voltage follower configuration with the drain connected to the +5 Volt signal  418  and the source connected to a voltage follower load resistor  362 . The output from the second FET  354  forms the PLFS  432  sampled by the A/D converter of the microprocessor  312 . Based on the PLFS  432 , the microprocessor  312  varies the frequency and duty cycle of the digital signal  421  to the first FET  314  to produce a high-voltage output ratio less than 80 percent for the PHO  428  and the NHO  430  to generate a bipolar ion concentration ratio greater than 80 percent from the positive-ion electrode  322  and the negative-ion electrode  324 . The RDN and second FET  354  circuit may be duplicated to provide the microprocessor  312  with the NLFS  434  from the NHO  430  (not shown). 
       FIG.  7    shows a seventh embodiment of the ionizer 301 g including: 1) a seventh signal conditioning element 307 g, 2) the step-up transformer  316 , 3) a positive voltage multiplier  318  connected to a positive-ion electrode  322 , and 4) a negative voltage multiplier  320  connected to a negative-ion electrode  324 . The seventh signal conditioning element 307 g comprises: 1) a first input terminal  303   a  and a second input terminal  303   b , 2) signal input processing circuit (a first diode  300 , a second diode  302 , a first capacitor  304 , a first resistor  306 , a first Zener diode  308 ), 3) a microprocessor  312  (or OSC) and a first FET  314 , and 4) a feedback circuit including a positive feedback comparator  356  and a positive RDN  341 . The feedback circuit is based on a comparator attached to the positive-ion electrode  322 . A wireless antenna  313  may be used to provide information regarding the status of the balanced bipolar ionizer. 
       FIG.  7    shows the same signal input processing circuit shown in  FIG.  2    to create the step-up transformer DC input voltage  424  and the +5 Volt signal  418  from an electrical power signal. Similar to  FIG.  5   , the RDN is comprised of a positive feedback 100 MΩ resistor  342  and a positive feedback 100 KΩ resistor  344  connected in series. The output from the positive RDN  341  is connected to the positive input of a positive feedback comparator  356 . The negative input of the positive feedback comparator  356  is connected to a comparator reference voltage  446 . The comparator reference voltage  446  is created by two resistors dividing the +5 Volt signal  418 . A first positive reference resistor  358  is connected to the +5 Volt signal  418  and the negative terminal of positive feedback comparator  356 . A second positive reference resistor  360  is connected to the negative terminal of positive feedback comparator  356  and ground. The comparator circuit may be connected to either the PHO  428  or the NHO  430 .  FIG.  7    only shows the PHO  428 . The comparator circuit compares the output from the RDN to a reference voltage (e.g., 2.5 Volts Direct Current or VDC) and provides the microprocessor  312  with a Positive Comparator Feedback Signal (PCFS  438 ). The PCFS  438  is a digital 1 if the output from the RDN is greater than 2.5 VDC. The PCFS  438  is a digital 0 if the output from the RDN is less than 2.5 VDC. Based on the PCFS  438 , the microprocessor  312  varies the frequency and duty cycle of the digital signal  421  to the first FET  314  which provides an excitation signal  422  to the step-up transformer  316  which varies the frequency and the duty cycle of the step-up transformer output voltage  426  which provides a DC high-voltage output ratio less than 80 percent for the PHO  428  and the NHO  430  and a bipolar ion concentration ratio greater than 80 percent to maintain a comparator signal between 1 and 0. The comparator circuit may be duplicated to provide the microprocessor  312  with a Negative Comparator Feedback Signal (NCFS  439 ) from the NHO  430  (not shown). 
       FIG.  8    shows time series measurements of the present invention the bipolar ionizer with a high-voltage output ratio less than 80 percent to generate a bipolar ion concentration ratio greater than 80 percent to eliminate or minimize ozone concentration. The absolute value of the negative DC high-voltage output is 1610 Volts referred to as the NHO  430 . The average positive DC high-voltage output is 2030 Volts referred to as the PHO  428 . The absolute value of the negative-ion concentration is 70 million ions per cubic centimeter (10 6  /cc). The average of the positive-ion concentration is 67 million ions/cc. The positive-ion concentration  528  and the negative-ion concentration  530  are sampled using an ion counter that captures a fraction of the total positive and negative-ion concentrations emitted from each electrode. The ion concentration ratios are more important than the magnitude of the ion concentrations. The high-voltage output ratio is 68 percent and the bipolar ion concentration ratio is 96 percent. The ozone concentration measured over 8 hours is zero parts per million (ppm) over a range of 20 to 29.3 VAC electrical signal inputs. 
       FIG.  9    provides test results of the balanced bipolar ionizer with a high-voltage output ratio less than 80 percent and bipolar ion concentration ratio greater than 80 percent.  FIG.  9    provides tests of two embodiments: 1) a positive high-voltage output greater than the absolute value of the negative high-voltage output (rows 1-3); and 2) an absolute value of the negative high-voltage output greater than the positive high-voltage output (rows 4-6). The positive greater than negative high-voltage output tests in rows 1-3 at input voltages of 20 to 29.3 VAC provide zero parts per million (ppm) ozone concentrations over an 8-hour test period (&lt; 0.05 ppm). The high-voltage output ratio is 67 to 68% and the bipolar ion concentration ratio is 86 to 96%. The bipolar ion concentration ratio is equal to a minimum of an absolute value of a negative-ion concentration and a positive-ion concentration divided by a maximum of the absolute value of the negative-ion concentration and the positive-ion concentration. The high-voltage output ratio is equal to a minimum of an absolute value of a negative high-voltage output and a positive high-voltage output divided by a maximum of the absolute value of the negative high-voltage output and the positive high-voltage output. 
       FIG.  9    shows test data for the absolute value of the negative high-voltage output greater than the positive high-voltage output embodiment (rows 4-6). Tests were performed at input voltages ranging from 20 to 29.3 VAC with zero ozone ppmv (&lt; 0.05 ppm) over a 24-hour test period. The high-voltage output ratio is less than 80 percent (i.e., 64 to 68%), and the bipolar ion concentration ratio is greater than 80 percent (i.e., 84 to 86%). 
       FIG.  10    provides laboratory tests of a known prior art bipolar ionizer with high-voltage output greater than or equal to 80 percent and bipolar ion concentration ratio less than 80 percent. The row 7-9 tests at input voltages of 20 to 29.3 VAC provide high-voltage output ratios of 90 to 100 percent, bipolar ion concentration ratios of 66 to 77%, and ozone concentrations of 0.08 to 0.27 ppm. The known prior art ozone concentrations are 1.6 to 5.4 times greater than the CARB and US FDA ozone exposure limit of 0.05 ppm. The voltage measurements shown in  FIG.  10    are measured at the emitting end of the positive-ion electrode and the negative-ion electrode. Unequal resistors (PER  364  and NER  365  shown in  FIG.  5   ) may be installed between the voltage multipliers and the electrodes for electrical safety. Unequal resistors may impact the voltage measurements of the high-voltage output at the ends of the positive- or negative-ion emitters. The difference in the values of the unequal resistors would not impact the ion generation since the impedance of air is between 1.3 to 3.3 times 10^16 ohms  (with ions present) and changes on the order of Mega Ohms (MΩs) between the unequal resistors would be insignificant with respect to the impedance of air (resistance of dry air is infinite with no ions present). The resistance of the unequal resistors may be determined by measuring the high-voltage output from each electrode using a high-voltage measurement circuit shown in  FIG.  5    where the RDN is changed for two sets of measurements. 
     A method of determining an unknown electrode resistor (e.g., PER  364  or NER  365 ) involves measuring a first voltage V1 with the HMC  363  using the first RDN1 resistor and measuring a second voltage V2 with the HMC  363  using the second RDN2 resistor. The first RDN1 resistor may comprise the positive feedback 100MΩ resistor  342  and the positive feedback 100 KΩ resistor  344 . The second RDN2 resistor may comprise a 200 MΩ resistor plus a 100 KΩ resistor. Equation 3 is used to determine the value of the PER  364  or the NER  365  resistor based on measurements of the first voltage V1 and the second voltage V2. 
     
       
         
           
             
               
                 PER 364 or NER 365 
               
             
             = 
             
               
                 RDN1 
                 − 
                 Vr 
                 
                   
                     RDN2 
                   
                 
               
             
             / 
             
               
                 Vr 
                 − 
                 1 
               
             
           
         
       
     
      Where, Vr = V1/V2 where the first voltage V1 is measured with the first RDN1 resistor and the second voltage V2 is measured with the second RDN2 resistor, and RDN2 = the second RDN2 resistor comprised of a 200 MΩ plus 100 KΩ resistor. 
       FIG.  11    shows an eighth embodiment of the ionizer  301   h  with at least one Air Quality Monitor (AQM) sensor and a feedback circuit  377 . The eighth embodiment shown in  FIG.  11    comprises: 1) an AC/DC converter  378 , 2) the step-up transformer  316 , 3) a positive voltage multiplier  318  connected to a positive-ion electrode  322 , 4) a negative voltage multiplier  320  connected to a negative-ion electrode  324 , 5) a first input terminal  303   a , 6) a second input terminal  303   b , 7) a microprocessor  312 , 8) a first FET  314 , 9) a feedback circuit  377 , and at least one sensor selected from the group consisting of: 10) a Volatile Organic Compound sensor or VOC sensor  372 , 11) a HCHO sensor  374 ), and 12) a Particulate Matter less than 2.5 micrometers sensor (a PM 2.5 sensor  376 ). The AC/DC converter  378  creates the DC voltages required by the ionizer  301   h . These voltages are the +5 Volt signal  418 , the -5 Volt signal  420 , and the step-up transformer DC input voltage  424  to the step-up transformer  316 . The positive voltage multiplier  318  creates the PHO  428  and the negative voltage multiplier  320  creates the NHO  430  by multiplying the step-up transformer output voltage  426  from the step-up transformer  316 . 
       FIG.  11    shows the feedback circuit scaling the PHO  428  and NHO  430  to a PLFS  432  and NLFS  434  respectively which are sampled by the microprocessor  312  using the AC/DC converter  378 . Based on the PLFS  432  and/or the NLFS  434 , the microprocessor  312  varies the frequency and duty cycle of the digital signal  421  to the first FET  314  which provides an excitation signal  422  to the step-up transformer  316 , which digital signal  421  varies the frequency and the duty cycle of the step-up transformer output voltage  426  which provides the DC high-voltage output ratio less than 80 percent for the PHO  428  and the NHO  430  and a bipolar ion concentration ratio greater than 80 percent from the positive-ion electrode  322  and the negative-ion electrode  324 .  FIG.  11    shows three sensors in an airflow serving the bipolar ionizer. The microprocessor  312  monitors the VOC sensor  372  using a first serial communication signal  452  carried on a first serial communication bus  372   a . The microprocessor  312  monitors the HCHO sensor  374  using a second serial communication signal  454  carried on a second serial communication bus  374   a . The microprocessor  312  monitors the PM 2.5 sensor  376  using a third serial communication signal  456  carried on a third serial communication bus  376   a . The AQM may communicate with each sensor using an Inter-Integrated Circuit bus (I2C) and unique addresses for each sensor. 
     In  FIG.  11    the microprocessor  312  consistently maintains the PHO  428  and NHO  430  within the DC high-voltage specification via the modulation and feedback process described above. If the microprocessor  312  detects an elevated concentration of VOCs or HCHO, the microprocessor  312  will de-energize the digital signal  421  to prevent the generation of bipolar ions until the concentration of the VOCs or HCHO is reduced. Also shown is a wireless antenna  313  to communicate using a WIFI (Wireless Fidelity), a Bluetooth (short-range wireless using UHF radio waves in the ISM bands, from 2.402 GHz to 2.480 GHz), or a LPWAN (Low-Power Wide-Area Network with data rates from 0.3 kbit/s to 50 kbit/s per channel). The microprocessor  312  monitors data or information selected from the group consisting of: 1) the PHO  428 , 2) the NHO  430 , 3) positive ion concentration, 4) negative ion concentration, 5) VOC concentration, 6) HCHO concentration, and 7) PM 2.5 concentration. If the microprocessor  312  detects 1) an elevated concentration of VOCs, HCHO, or PM 2.5, or 2) the PHO  428  or NHO  430  are above or below specifications, and the microprocessor  312  cannot modulate the frequency and/or duty cycle of a digital signal  421  to maintain the bipolar ion concentration within specifications, then the microprocessor  312  may transmit an alarm message using the above wireless communication. If the PHO  428  and NHO  430  regain their specified values, and/or VOCs, HCHO, or PM 2.5 decrease below the threshold specifications, then the microprocessor  312  will send a message indicating that the PHO  428  and NHO  430  or VOCs, HCHO, or PM 2.5 are within specifications. 
       FIG.  12    shows an embodiment of the ionizer with an AQM system  371  that is not integrated with the ionizer. The embodiment shown in  FIG.  12    comprises: 1) an ionizer  301 , 2) a HVAC system  398 , 3) a thermostat  396 , 4) a 24VAC transformer  310 , and 5) and an Air Quality Monitor (AQM) system or AQM system  371  comprising an AQM  370  and at least one sensor selected from the group consisting of: 6) a VOC sensor  372 , 7) a HCHO sensor  374 , and 8) a PM 2.5 sensor  376 . The function of the thermostat  396  and HVAC system  398  are described above. The ionizer  301  may operate with a transformer providing a range of electrical signal inputs selected from the group consisting of: 20 to 30 VAC,  110  to 130 VAC,  210  to 250 VAC,  208  to 280 VAC, 2 to 15 Volts Direct Current (VDC), and 20 to 30 VDC. The control terminal  303   d  is connected to output  370   a  of the AQM  370 . In one embodiment, the control terminal  303   d  is connected internally to the Balanced bipolar ionizer ground, shown as a dashed line. In this embodiment, the AQM  370  monitors the VOC sensor  372 , the HCHO sensor  374 , and the PM 2.5 sensor as described above in  FIG.  11   . The AQM  370  communicates with the VOC sensor  372  using the first serial communication signal  452  carried on the first serial communication bus  372   a . The AQM  370  communicates with the HCHO sensor  374  using the second serial communication signal  454  carried on the second serial communication bus  374   a . The AQM communicates with the PM 2.5 sensor  376  using the third serial communication signal  456  carried on the third serial communication bus  376   a . An I2C bus may be used as described above. 
     When the VOC, HCHO, and PM 2.5 concentrations are below the threshold specifications, the AQM shown in  FIG.  12    directs the control signal  450  on output  370   a  to a ground voltage which is equivalent to a signal  400   b  of the 24 VAC transformer  310 . This connection allows current to flow between the at least one ionizer inputs, the first input terminal  303   a  and the second input terminal  303   b  and the control terminal  303   d  and enables the ionizer  301  to generate the positive and/or negative ion concentration using the AC/DC converter  378 , the signal conditioning element (not shown), the step-up transformer  316 , the Positive Voltage Multiplier (PVM)  318  is connected to the positive-ion electrode  322 , and the Negative Voltage Multiplier (NVM)  320  is connected to the negative-ion electrode  324 . If the VOC or HCHO concentrations are greater than the threshold specifications (e.g., 0.4 ppmv for VOCs or 0.1 for HCHO), then the AQM  370  may de-energize or adjust the Positive DC High-voltage Signal (PDHS) or the PHO  428  or the negative DC High-voltage Signal or (NDHS) or NHO  430  and not produce or reduce the positive-ion concentration  528  or the negative-ion concentration  530 . The AQM  370  may also cause the output  370   a  to float which stops the flow of current from the first input terminal  303   a  or the second input terminal  303   b  causing the bipolar ion generation to cease. Stopping or adjusting the bipolar ion concentration may avoid producing or enhancing concentrations of smaller, potentially oxidized daughter VOCs or HCHO when the VOC or HCHO concentrations are greater than the threshold levels. 
     In another embodiment of  FIG.  12   , the control terminal  303   d  is connected internally to the microprocessor  312 , shown as a second dashed line and the ground of the ionizer  301  is connected to the signal  400   b  of the 24 VAC transformer  310 . The AQM  370  monitors the sensors as described above, but in this embodiment, the control signal  450  may be a digital or analog control signal sent by the AQM  370  using output  370   a  to the control terminal  303   d  to the microprocessor  312  indicating the levels of VOCs or HCHO. The microprocessor  312  processes the control signal  450  to de-energize or reduce a positive and/or negative DC high-voltage output as described above. The AQM  370  is shown with an optional wireless antenna  313   a  to communicate data and/or messages to a user using a software application (APP). Data may include concentrations of VOC, HCHO, and/or PM 2.5 or DC high-voltage signals on the electrodes or bipolar ion concentrations. 
       FIG.  13    shows an embodiment of a system including 1) the ionizer  301 , 2) HVAC system  398 , 3) a thermostat  396 , 4) a 24 VAC transformer  310 , 5) an Efficient Fan Controller (EFC) 7, and 6) and an AQM system  371  comprising 7) an AQM  370  and at least one sensor selected from the group consisting of: 8) a VOC sensor  372 , 9) a HCHO sensor  374 , and 10) a PM 2.5 sensor  376 . The ionizer  301  could be embodied as described in  FIG.  12    with the addition of an ion concentration output  303   e  used to communicate an ion concentration using a fifth serial communication signal  458  to the EFC 7 using an ion concentration input  219   b . The thermostat  396  and the HVAC system  398  are described above. In this embodiment the ionizer  301  and the AQM  370  function similar to  FIG.  12   . The EFC 7 receives control signals from the thermostat  396 . A heat W input  216  receives a heat W signal  406  from a heat W terminal  386 . A fan G input  214  receives a fan G signal  404  from a fan G terminal  384 . An AC Y input  215  receives an AC Y signal  405  from an AC Y terminal  382 . A hot R input  213  receives a hot R signal  400  from hot R terminal  380 . A Common (a COM C input  221 ) is connected to the COM C terminal (ground connection) of the 24 VAC transformer  310 . The EFC 7 provides a fan G signal  404   b  from a fan G signal output  212  of the EFC 7 to a fan G terminal  384   a  of the HVAC system  398  and the fan G input or the first input terminal  303   a  of the ionizer  301 . The HVAC system  398  also receives a heat W signal from the heat W terminal  386  to the heat W terminal  386   a , an AC Y signal from the AC Y terminal  382  to the AC Y terminal  382   a , a hot R signal from the hot R terminal  380  to the hot R terminal  380   a , and a COM C terminal  388  is connected to the COM C of the 24 VAC transformer  310 . 
     The EFC 7 shown in  FIG.  13    performs data processing and wireless communication using a wireless antenna  313   b . The data processing and wireless communication functions may also be embodied in the ionizer  301 . The VOC, the HCHO, and the PM 2.5 concentrations are transmitted from the AQM concentration output  370   b  of the AQM  370  to the AQM concentration input  219   a  using a fourth serial communication signal  450   b . The EFC 7 also monitors the status of the control signal  450  through the common monitor input  218 . If the common monitor input  218  is at the common voltage level, the ionizer  301  is powered and generating ions unless otherwise faulted. If the common monitor input  218  is not at the common voltage, the ionizer  301  is either de-energized or adjusting a positive and/or negative DC high-voltage output to stop generating or reduce the ion concentration as described above. The ion concentration output  303   e  is connected to the ion concentration input  219   b  and the ion concentration levels are communicated using the fifth serial communication signal  458 . The EFC 7 (or ionizer  301 ) performs data processing and wireless communication using a wireless antenna  313   b  to periodically transmit at least one measurement selected from the group consisting of: 1) the PHO  428 , 2) the NHO  430 , 3) positive ion concentration, 4) negative ion concentration, 5) VOC concentration, 6) HCHO concentration, and 7) PM 2.5 concentration. 
       FIG.  14    shows an embodiment of an AQM system  371  used to control the ionizer  301  comprising: 1) an AQM  370  comprising, 2) a microprocessor  312 , 3) an AC/DC converter  378   a , 4) a switch  379  or Digital to Analog Converter (DAC), and at least one sensor selected from the group consisting of: 5) a VOC sensor  372 , 6) a HCHO sensor  374 , and 7) a PM 2.5 sensor  376 . The AC/DC converter  378   a  provides power to the microprocessor  312  and to the sensors. The microprocessor  312  monitors the VOC sensor  372 , the HCHO sensor  374 , and the PM 2.5 sensor  376  as described above. When the VOC, HCHO, and PM 2.5 concentrations are within specifications, the microprocessor  312  uses the switch  379  or DAC to provide a control signal  450 . In one embodiment, the control signal  450  may be a ground voltage which is equivalent to the signal  400   b  of the 24VAC transformer  310  (see  FIG.  13   ). This control signal  450  allows current to flow between the at least one balanced bipolar ionizer inputs, the first input terminal  303   a  and the second input terminal  303   b  which allows the ionizer  301  to generate the positive-ion concentration  528  and/or the negative-ion concentration  530  (see  FIG.  13   ). If the VOC or HCHO concentration in an airflow serving the ionizer  301  exceeds specifications, then the microprocessor  312  may use the switch  379  or DAC to provide a control signal  450  on the output  370   a  which may be proportional to the VOC concentration. The ionizer  301  processes this signal and either de-energizes or reduces the positive and/or negative DC high-voltage signal to not produce or to adjust the positive and/or negative ion concentration. The microprocessor  312  may also use the switch  379  or DAC to cause the control signal  450  to float where the ionizer  301  is de-energized or where the control signal  450  is used to reduce the positive and/or the negative ion concentration. For the switch  379 , the microprocessor  312  may de-energize switch  379  and cause the control signal  450  to float. The switch  379  or DAC may be replaced with a method of serial communication to provide VOC levels to the ionizer  301 . The microprocessor  312  provides WIFI communication using a wireless antenna  313 . 
       FIG.  15    shows a first method  101  to control the ionizer to maintain a consistent unbalanced DC high-voltage output ratio and generate a balanced bipolar ion concentration ratio to minimize an ozone concentration to zero parts per million by volume (ppmv) over a range of input voltages. Depending on the transformer, the range of input voltages may vary from: 20 to 30 VAC,  110  to 130 VAC,  210  to 250 VAC,  208  to 280 VAC, 2 to 15 VDC, or 20 to 30 VDC. Step  102  processes the input voltages. Step  103  converts the at least one DC high-voltage signal to at least one feedback signal or error value and compares the at least one feedback signal or error value to a first specification (spec) corresponding to the ionizer voltage to determine whether the at least one feedback signal is within the first specification (described above). Step  104  monitors the at least one feedback signal corresponding to the negative and/or positive DC high-voltage signals. If step  105  is Yes (Y), and the at least one feedback signal is within the first specification or ionizer voltage (NDHS or NHO and/or PDHS or PHO), then the method proceeds to step  108  to continue generating the consistent ion concentration and proceeds to step  111  to an APP update tim er where the frequency of APP update messages is controlled by step  113  which checks whether or not it is time to update the APP. If step  113  is Yes (Y), the method proceeds to step  115  to process the ionizer voltages to report ion concentrations and prepare data or messages. After step  113 , if NO (N), the method loops back to step  103 . 
     Per  FIG.  15   , if the at least one feedback signal or error value corresponding to the ionizer voltages are not within the first specification (spec) at step  105 , then the method proceeds to step  107 . At step  107 , the method determines if the microprocessor  312  has reached an ionizer modulation limit where the microprocessor  312  can no longer modulate the digital signal  421  to a first FET  314  which provides an excitation signal  422  to the step-up transformer  316  which varies the frequency and the duty cycle of the step-up transformer output voltage  426  which provides the specified the ionizer voltages on the electrodes. If step  107  determines that the ionizer modulation is No (N) where the microprocessor has not reached a modulation limit, then the method proceeds to step  109 . At step  109  the method modulates the XFMR (i.e., step-up transformer) excitation frequency and/or duty cycle of the digital signal  421  as described above which provides the DC high-voltage signal and maintains consistent ionizer voltages and ion concentrations. After step  109 , the method loops back to step  103 . As described above, the microprocessor varies the frequency and duty cycle of the digital signal to control the excitation signal for the step-up transformer (XFMR) and modulate the frequency and the duty cycle of the step-up transformer output voltage to consistently maintain the at least one DC high-voltage signal and generate a consistent ion concentration over a range of electrical signal inputs. 
     If step  107  of  FIG.  15    is Yes (Y) where the ionizer modulation limit has been reached in step  107 , then the method proceeds to step  121  and resets to initial modulation parameters using an algorithm to begin the method from an initial state. The modulation limits of the frequency and/or duty cycle may vary depending on the transformer magnetics. In one embodiment, the modulation limit frequency may be less than 8 kHz and the duty cycle may be equal to 0 percent. In another embodiment, the frequency may be greater than 12 kHz and the duty cycle may be equal to 100 percent. For this case the method is within the modulation limit when the frequency is between 8 to 12 kHz and duty cycle less than 100 percent. A modulation limit may be reached based on at least one fault selected from the group consisting of: an electrical short on the positive-ion electrode or the negative-ion electrode, a power supply voltage input fault beyond a specified range of 20 to 30 VAC, a power supply or transformer failure, an electronic component failure; and providing at least one message selected from the group consisting of: a text message, an email message, an audio communication, a voice mail message, or a wireless communication method. Faults are identified in step  123  by a flashing LED or sending data and/or an alarm message to a user. After step  121 , the method proceeds to step  115  to process the ionizer voltages to ion concentrations and prepare data or messages. 
     After step  115  of  FIG.  15   , the method proceeds to step  117  to check if the ionizer voltages are within spec again, to determine which type of messages are to be sent to a user. If step  117  is No (N) where the ionizer voltages are not within spec, then the method proceeds to step  123  to provide a flashing LED lamp indicator or to send data and/or alarm messages to the APP (software) of ionizer voltages or ion concentrations outside the spec. If step  117  is Yes (Y) where the ionizer voltages are within the spec, then the method proceeds to step  119  to provide a continuous LED lamp indicator or send data and/or messages to the software application (APP) of ionizer voltages or ion concentrations within spec. The data and/or alarm messages may be sent to a user using at least one communication method selected from the group consisting of: a graphical display, a text message, an email message, an audio communication message, a voice mail message, or a wireless communication method. The wireless communication may use a cellular system, a WIFI (wireless fidelity), a Bluetooth (short-range wireless using UHF radio waves in the ISM bands, from 2.402 GHz to 2.480 GHz), a Low-Power Wide-Area Network (LPWAN with data rates from 0.3 kbit/s to 50 kbit/s per channel), or an ultra-low power Long-range Radio (LoRa) or LoRA Wide Area Network (LoRaWAN) communication protocol. After step  119  or step  123 , the method loops back to step  103  to continue monitoring the positive and/or negative ionizer electrode voltages. Step  125  provides an optional reboot of the microprocessor of the ionizer for several minutes if continuous fan operation is greater than several hours to enhance the ionizer lifetime and clear accumulated errors in the microprocessor memory to improve performance of the microprocessor and the ionizer. 
       FIG.  16    shows a second method  127  to perform a similar control as the first method  101  while also providing a control to de-energize the ionizer based on at least one Indoor Air Quality (IAQ) concentration selected from the group consisting of: a Volatile Organic Compound (VOC) concentration (parts per million or ppm), a formaldehyde (HCHO) concentration in ppm, or a Particulate Matter less than 2.5 micrometers concentration (a PM 2.5). The ionizer de-energizes or reduces the positive and/or negative DC high-voltage signal to not produce or reduce a positive and/or negative ion concentration when the VOC or HCHO concentrations are greater than the spec. The spec may be a first threshold value for a VOC or second threshold value for a HCHO. The first threshold of the spec may comprise a Permissible Exposure Level (PEL) of 0.75 ppmv and an action level of 0.4 ppmv for a VOC per the US Department of Housing and Urban Development (HUD) level for residential mobile homes. The second threshold of the spec may comprise a 0.1 ppmv for HCHO per OSHA. The method may comprise adjusting the ion concentration energy below an energy threshold that does not disassociate VOCs to daughter VOCs (i.e., less than 9 electron Volts (eV) or another eV threshold). 
       FIG.  16    step  128  processes a range of input voltage (e.g., 20 to 30VAC, etc.). At step  129  the method converts the at least one DC high-voltage signal to at least one feedback signal or error value and compares the at least one feedback signal or error value to the first specification (described above). At step  131  the method monitors the at least one feedback signal corresponding to the DC high-voltage signal (e.g., the positive and/or negative ionizer electrode voltage), VOC, HCHO, and PM 2.5, and proceeds to step  131 . If step  131  is Yes (Y) the VOCs, PM 2.5 and HCHO concentrations are within specification, the method proceeds to step  133 . At step  133 , if the at least one feedback signal or error value are within the first specification (described above), then the method continues to step  134  and continues generating ions. At step  136 , the method updates an APP update timer with a software application and continues to step  138 . If step  138  is No (N) the time to update the APP has not expired, then the method loops back to step  129 . If step  138  is Yes (Y), the time to update APP is expired, then the method proceeds to step  145  to process alarm messages, ionizer voltages to ion concentrations, VOC, HCOC, and PM 2.5 measurements and prepare data and/or messages and proceeds to step  147 . If no alarms are generated and step  147  is No (N), then the method proceeds to step  151  to continue providing a continuous LED lamp indicator or to send a message to the APP (software) regarding the ionizer voltages, ion concentrations, VOC, HCOC and/or PM 2.5 concentrations. The message may be sent using at least one communication method selected from the group consisting of: a graphical display, a text message, an email message, and an audio communication message. After step  151 , the method loops back to step  129 . 
     If step  133  of  FIG.  16    is No (N), the method proceeds to step  137  and checks the ionizer modulation limit (upper or lower) where the microprocessor  312  cannot modulate the digital signal  421  to a first FET  314  to the step-up transformer  316  to achieve the first specification corresponding to the second specification of the positive and/or negative ionizer electrode voltage output (the spec is +1.7 kV +/- 0.4 kV to +2.5 kV +/- 0.6 kV on the positive-ion electrode  322  and -2.5 kV +/- 0.6 kV to -1.7 kV +/- 0.4 kV on the negative-ion electrode  324 ). If step  137  is No (N) and the ionizer voltages are not within spec and the ionizer modulation is not reached, then the method proceeds to step  143  and modulates the transformer (XFMR) excitation frequency and/or duty cycle to maintain consistent ionizer voltages and ion concentrations and the method loops back to step  129 . If step  137  is Yes (Y) where the ionizer modulation limit is reached, then the method proceeds to step  139  to reset the modulation parameters as described above. 
     After step  139  of  FIG.  16   , the method goes to step  142  to generate an alarm message, then to step  145  to process the alarm message, and then to step  147 . If step  147  is Yes (Y), the method proceeds to step  149  to send the alarm message using a flashing LED or the APP (software) and sends the ionizer voltage and ion concentrations using the at least one communication method, and loops back to step  129 . If step  135  is No (N) the method proceeds to step  142  to generate a PM 2.5 alarm without de-energizing the ionizer voltage (in step  141  which is skipped). If step  135  is Yes (Y), then the method proceeds to step  141  to de-energize or reduce the positive and/or negative DC high-voltage signal to not produce or reduce a positive and/or negative ion concentration when the VOC or HCHO concentrations are greater than the spec. After step  141  the method proceeds to step  142  to generate alarm messages and proceeds to step  145  to process the alarm messages and prepare data and/or messages. After step  145 , the method proceeds to step  147 . If step  147  is Yes (Y), then the method continues to step  149  to provide a flashing LED or send an alarm message to the software application (APP) of ionizer voltages, ion concentrations, VOC, HCHO or PM 2.5 concentrations and loops back to step  129 . After step  149  or step  151 , the method returns to step  129  to continue the second method. Alternatively, the method may provide an optional step (not shown) to reboot the microprocessor of the ionizer for several minutes if continuous fan operation is greater than several hours to enhance the ionizer lifetime and performance (see step  125  in  FIG.  15   ). 
       FIG.  17    shows a third method  157  for de-energizing the digital signal  421  to a first FET  314  to the step-up transformer  316  if the concentration of VOCs or formaldehyde (HCHO) is greater than a spec (e.g., a threshold specification of 0.40 ppmv for VOCs and 0.1 ppmv for HCHO). Step  159  converts the at least one DC high-voltage signal (e.g., positive and/or negative ionizer electrode voltage) to at least one feedback signal or error value used by the microprocessor  312  to monitor the ionizer voltage and compare to the specification for the ionizer voltage. Step  159  also monitors VOC, HCHO, or PM 2.5 concentrations with a VOC sensor  372 , a HCHO sensor  374 , or a PM 2.5 sensor  376  and proceeds to step  161 . If step  161  is Yes (Y), the at least one feedback signal is within the first specification and the VOCs, PM 2.5 and HCHO concentrations are within specification. The method then goes to step  165  to generate or continue generating the ion concentration and reports the ion concentration is within the second specification and the VOC, the HCHO, and the PM 2.5 concentrations within specifications. The method continues to step  169  to update the APP tim er, and step  173  to check time to update the APP. If step  173  is No (N) the method loops back to step  159 . If step  173  is Yes (Y), the method continues to step  174  to process alarm messages, ionizer voltages to ion concentrations, VOC, HCHO and PM 2.5 measurements and prepare data and/or messages as described above. 
     If step  161  of  FIG.  17    is No (N), the method goes to step  162  to check if the at least one feedback signal is within the first specification. If No (N), the method goes to step  164  and modulates the XFMR (i.e., step-up transformer) excitation frequency and/or duty cycle of the digital signal as described above which provides the DC high-voltage signal and maintains consistent ionizer voltages and ion concentrations. Not shown are steps where the ionizer modulation limit is reached or the modulation parameters are reset where the method skips step  164  and loops back to step  159 . After step  164 , the method loops back to step  159 . If step  162  is Yes (Y), the method goes to step  163  where the method checks if the VOC or the HCHO concentrations are greater than the specification (spec). If step  163  is No (N) the method proceeds to step  171  to generate a PM 2.5 alarm without de-energizing the ionizer voltage (in step  167  which is skipped). If step  163  is Yes (Y), then the method proceeds to step  167  de-energize or adjust the ionizer voltage based on the VOC or HCHO levels being greater than the specification as described above. After step  167  the method proceeds to step  171  to generate alarm messages and proceeds to step  174  to process the alarm messages and prepare data and/or messages and proceeds to step  175 . If step  175  is Yes (Y), the method goes to step  179  to provide a flashing LED or send an alarm message to a software application (APP) of ionizer voltage and ion concentrations, VOC, HCHO or PM 2.5 concentrations and loops back to step  159  to continue. If step  175  is No (N), the method proceeds to step  177  to provide a continuous LED signal or send a message to the APP of ionizer voltage, ion concentration, VOC, HCHO, or PM2.5 concentration within specifications. After step  177  or step  179 , the method returns to step  159  to continue the third method. Alternatively, the method may provide an optional step (not shown) to reboot the microprocessor of the ionizer for several minutes if continuous fan operation is greater than several hours to enhance ionizer life and performance (see step  125  in  FIG.  15   ). 
       FIG.  18    provides laboratory test data and a first curve  181  showing a positive ion concentration in million ions per cubic centimeter (ions/cc) versus a DC high-voltage positive signal in kilovolts (kV).  FIG.  18    also provides a second curve  185  showing a negative ion concentration in million ions/cc curve versus a DC high-voltage negative signal (kV). Ion concentrations are measured using an accurate ion counter Model AIC2 manufactured by Alpha Labs Inc. (https://www.alphalabinc.com/product/aic2/).  FIG.  18    provides a third curve  183  showing a first equation (Eq. 4) based on a regression equation of the laboratory test data of the positive ion concentration in million ions/cc versus the DC high-voltage positive signal (kV) . Eq. 4 may be used to calculate the positive ion concentration (million ions/cc) based on accurate measurements of the DC high-voltage positive signal (kV). The method calculates and reports the positive-ion concentration based on a first equation (Eq. 4) where an independent variable is the positive DC high-voltage signal. 
     
       
         
           
             y = 65 
             .42 
               
             
               x 
               3 
             
             − 
             203.81 
               
             
               x 
               2 
             
             + 
             158.15 
               
             x 
           
         
       
     
      Where, y = positive ion concentration (million ions/cc), and x = DC high-voltage positive signal (kV). 
       FIG.  18    provides a fourth curve  187  showing a second equation (Eq. 5) based on a regression equation of the laboratory test data of the negative ion concentration in million ions/cc versus the DC high-voltage negative signal (kV). Eq. 5 may be used to calculate the negative ion concentration (million ions/cc) based on accurate measurements of the DC high-voltage negative signal (kV). The method calculates and reports the negative-ion concentration based on a second equation where the independent variable is the negative DC high-voltage signal. 
     
       
         
           
             y 
             = 
             − 
             7.8316 
               
             
               x 
               3 
             
             − 
             97.275 
               
             
               x 
               2 
             
             − 
             71.277 
               
             x 
           
         
       
     
      Where, y = negative ion concentration (million ions/cc), and x = DC high-voltage negative signal (kV). 
       FIG.  19    shows the ionizer  301  with positive-ion electrode  322  and/or a negative-ion electrode  324  installed at the inlet of the fan  206  of the HVAC system  200  (both electrodes could be negative). The VOC sensor  372   u  and the formaldehyde sensor or the HCHO sensor  374   u  and the at least one air filter  249  are installed upstream of the bipolar ionizer. The at least one sensor or the at least one air filter may be installed with the bipolar ionizer where the at least one sensor is installed upstream or downstream of the bipolar ionizer and the at least one air filter is installed upstream of the bipolar ionizer. A Minimum Efficiency Reporting Value (MERV) rated air filter with the manganese oxide catalyst may be comprised of at least one catalyst selected from the group consisting of: a manganese sulfate or MnSO4 catalyst, a sodium permanganate or NaMnO4 catalyst, and a cryptomelane potassium manganese oxide mineral or K(Mn4+,Mn2+)8O16 catalyst. The AQM  370   s  is connected to these sensors and the VOC sensor  372   d  and HCHO sensor  374   d  which are installed downstream of the bipolar ionizer. The AQM  370   s  is also shown with wireless communication or bluetooth to communicate with the smart thermostat or other device such as a mobile phone smart home device, smart watch, computer, network, or automobile. The supply duct  246  connects the HVAC system  200  to the conditioned space  201  and the return duct  248  connects the conditioned space  201  to the HVAC system  200 . 
       FIG.  19    shows a smart thermostat  396   a  controlling the HVAC system  200  and connected to the VOC sensor  372   c  and the HCHO sensor  374   c . Wireless or bluetooth communication antennas are shown on the smart thermostat  396   a , the VOC sensor  372   c , and the HCHO sensor  374   c . A PM 2.5 sensor (not shown) may also be installed with each set of sensors.  FIG.  19    shows the at least one sensor or the at least one air filter may be installed upstream or downstream of the ionizer and the at least one air filter may be installed upstream of the ionizer. The at least one air filter is selected from the group consisting of: the MERV rated air filter with activated carbon, a High Efficiency Particulate Air (HEPA) filter, or the MERV rated air filter with manganese oxide catalysts comprising at least one catalyst selected from the group consisting of: a manganese sulfate or MnSO4 catalyst, a sodium permanganate or NaMnO4 catalyst, and a cryptomelane potassium manganese oxide mineral or K(Mn4+,Mn2+)8O16 catalyst. The air filter may comprise manganese oxide catalysts to remove formaldehyde through catalytic oxidation to the avoid producing concentrations of smaller, potentially oxidized daughter VOCs such as HCHO.  FIG.  19    shows the AQM  370   s  and/or smart thermostat  396   a  monitoring the DC high-voltage electrode signals, ion concentrations, VOCs, HCHO, or PM 2.5 concentrations and controlling the ionizer  301 , the HVAC system  200 , or the fan  206  to improve indoor air quality, thermal comfort, and energy efficiency. The ionizer  301  and the at least one air filter  249  reduce or eliminate pollutants (VOCs, HCHO, and PM 2.5) and pathogens (viruses, bacteria, fungi, mold). 
     Known bipolar ionizers may produce high ozone concentrations greater than the 24-hour Time Weighted Average (TWA) of 0.05 parts per million by volume (ppmv) per regulations established by the California Air Resources Board (CARB) for indoor air cleaning devices (AB 2276) or the United States (US) Food and Drug Administration (FDA). High ozone concentrations create an unresolved problem regarding human health. Field tests indicate that some bipolar ionizers may produce nearly zero bipolar ionization when installed with opposing magnetic fields from rare earth magnets used to attach bipolar ionizers to sheet metal surfaces of HVAC ducts or fan housings. Research studies indicate bipolar ionizers may enhance concentrations of smaller, potentially oxidized daughter VOCs such as HCHO (Zeng et al 2021). 
     The present invention comprises a feedback control to provide consistent DC high-voltage output over a range of 20 to 30 VAC electric signal inputs to provide consistent ion concentrations to deactivate pathogens and produce zero or 0.0 ppmv ozone concentrations over a 24-hour TWA. The present invention also comprises sensors to monitor VOCs and/or HCHO in the airflow being treated by the ionizer. If the monitored VOC and/or HCHO concentrations are greater than a threshold level, then the present invention de-energizes or reduces the positive DC high-voltage output and/or the negative DC high-voltage output to stop generating the ion concentration or reduce the ion concentration energy to avoid producing or enhancing concentrations of smaller, potentially oxidized daughter VOCs or HCHO. 
     The ionizer comprises: (1) at least one input terminal for at least one electrical signal input to energize the bipolar ionizer; (2) a signal conditioning element to process the at least one electrical signal input and provide an analog or a digital signal; (3) a step-up transformer to receive the analog or the digital signal from the signal conditioning element and provide a step-up transformer output voltage; (4) a negative voltage multiplier to receive the step-up transformer output voltage and provide a negative high-voltage output to a negative-ion electrode to generate a negative-ion concentration; and (5) a positive voltage multiplier to receive the step-up transformer output voltage and provide a positive high-voltage output to a positive-ion electrode to generate a positive-ion concentration, wherein: the positive voltage multiplier and the negative voltage multiplier provide a high-voltage output ratio less than 80 percent, and the high-voltage output ratio is equal to a minimum of an absolute value of a negative high-voltage output and a positive high-voltage output, divided by a maximum of the absolute value of the negative high-voltage output and the positive high-voltage output. 
     The signal conditioning element comprises at least one electrical component selected from the group consisting of: (1) a wire to conduct only one electrical signal input and provide the excitation signal to the step-up transformer, (2) at least one optically isolated triac to conduct the at least one electrical sig nal input and provide the excitation signal to the step-up transformer, (3) at least one relay to conduct the at least one electrical signal input and provide the excitation signal to the step-up transformer, (4) two diodes and a capacitor to conduct the at least one electrical sig nal input to a resistor and a Zener diode, a microprocessor, and a first FET to provide the excitation signal to the step-up transformer, and (5) two diodes and a capacitor to conduct the at least one electrical signal input to two resistors, a capacitor, a Zener diode, an oscillator, and the first FET to provide the excitation signal to the step-up transformer. 
     The signal conditioning element further includes: (1) at least one Resistor Divider Network (RDN) to reduce the positive high-voltage output or the negative high-voltage output to produce at least one high-impedance voltage signal; and (2) at least one active element selected from the group consisting of: an Operational Amplifier (Op Amp), a second FET, and a feedback comparator, wherein the at least one active element converts the at least one high-impedance voltage signal to at least one feedback signal, wherein the at least one feedback signal is used by a microprocessor to vary a frequency and a duty cycle of a digital signal  421  to a first FET  314  to control the excitation signal  422  for the step-up transformer and modulate the frequency and the duty cycle of the step-up transformer output voltage to maintain the high-voltage output ratio less than 80 percent and generate the bipolar ion concentration ratio greater than 80 percent to minimize an ozone concentration over a range of electrical signal inputs described above. The at least one active element maintains a consistent negative DC high-voltage output to a negative-ion electrode to generate a negative-ion concentration and a consistent positive DC high-voltage output to a positive-ion electrode to generate a positive-ion concentration. 
     The at least one feedback signal is a low-voltage feedback signal or a comparator feedback signal. The at least one input terminal further may be at least two input terminals to allow the at least one electrical signal input to energize the bipolar ionizer wherein the at least one electrical signal input is selected from at least two electrical signal inputs. The at least one electrical signal input is used to energize the bipolar ionizer to avoid operating the bipolar ionizer continuously which wastes energy and causes dust to accumulate on the negative-ion electrode or the positive-ion electrode when a fan is off which reduces the negative-ion concentration or the positive-ion concentration. The positive voltage multiplier provides at least one more multiplier stage than the negative voltage multiplier or the negative voltage multiplier provides at least one more multiplier stage than the positive voltage multiplier to provide the high-voltage output ratio less than 80 percent and the bipolar ion concentration ratio greater than 80 percent. The bipolar ionizer may include a Light Emitting Diode (LED) or a wireless communication module and antenna to provide status information or fault alarm messages. 
     The ionizer control converts at least one Direct Current (DC) high-voltage signal to at least one feedback signal where the at least one DC high-voltage signal is selected from the group consisting of: a NDHS on a negative-ion electrode generating a negative-ion concentration, and a PDHS on a positive-ion electrode generating a positive-ion concentration. The method also comprises monitoring the at least one feedback signal corresponding to the at least one DC high-voltage signal and comparing the at least one feedback signal to a first specification to determine whether the at least one feedback signal is within the first specification. The method varies a frequency and a duty cycle of a digital signal to control an excitation signal for a step-up transformer and modulates the frequency and the duty cycle of a step-up transformer output voltage to consistently maintain the at least one feedback signal within the first specification and maintain the at least one DC high-voltage signal within a second specification to generate a consistent ion concentration over a range of electrical signal inputs. 
     The at least one feedback signal is a low-voltage feedback signal or a comparator feedback signal and the first specification for the at least one feedback signal is selected from the group consisting of: a Negative Low-voltage Feedback Signal (NLFS) first specification is +1.7 V +/- 0.4 V to +2.5 V +/- 0.6 V where the NLFS is inverted to a positive signal and is approximately one one-thousandth of the NDHS, a Positive Low-voltage Feedback Signal (PLFS) first specification is +1.7 V +/- 0.4 V to +2.5 V +/- 0.6 V where the PLFS is approximately one one-thousandth of the PDHS, a Negative Comparator Feedback Signal (NCFS) first specification is between 0 and 1 where the NCFS is 1 when the NDHS is less than the second specification and the NCFS is 0 when the NDHS is greater than the second specification, and a Positive Comparator Feedback Signal (PCFS) first specification is between 0 and a 1 where the PCFS is 1 when the PDHS is greater than the second specification and the PCFS is 0 when the PDHS is less than the second specification. The second specification for the at least one DC high-voltage signal is selected from the group consisting of: the NDHS second specification is -2.5 kV +/- 0.6 kV to -1.7 kV +/- 0.4 kV, and the PDHS second specification is +1.7 kV +/- 0.4 kV to +2.5 kV +/- 0.6 kV. The range of electrical signal inputs is selected from the group consisting of: 20 to 30 VAC,  110  to 130 VAC,  210  to 250 VAC,  208  to 280 VAC, 2 to 15 VDC, and 20 to 30 VDC. 
     The ionizer control method comprises monitoring and processing the at least one feedback signal and calculating and reporting at least one parameter selected from the group consisting of: a positive DC high-voltage signal, the positive-ion concentration based on a first equation with the positive feedback signal as a first independent variable, a negative DC high-voltage signal, and the negative-ion concentration based on a second equation with the negative feedback signal as a second independent variable. Reporting may include providing data to a software application on a computer, a mobile phone, a watch, or other electronic communications technology regarding the at least one parameter. The ionizer control method may also comprise reporting at least one message selected from the group consisting of: a continuous LED signal, a discontinuous or flashing LED signal, an analog electrical signal, a digital electrical signal, a text message, an email message, a graphical display, an audio communication, a voice mail message, or a wireless communication method. The wireless communication may use a cellular system, a WIFI (wireless fidelity), a Bluetooth (short-range wireless using UHF radio waves in the ISM bands, from 2.402 GHz to 2.480 GHz), a Low-Power Wide-Area Network (LPWAN with data rates from 0.3 kbit/s to 50 kbit/s per channel), or an ultra-low power Long-range Radio (LoRa) or LoRA Wide Area Network (LoRaWAN) communication protocol. Reporting may include at least one ionizer fault selected from the group consisting of: an electrical short on the negative-ion electrode, a power supply voltage input fault beyond a specified range, a power supply or transformer failure, and an electronic component failure. 
     The ionizer control method may comprise monitoring a Volatile Organic Compound (VOC) concentration or a formaldehyde (HCHO) concentration in an airflow serving the ionizer, and de-energizing or adjusting the DC high-voltage signal and the ion concentration when the VOC concentration is greater than or equal to a first threshold or the HCHO concentration is greater than or equal to a second threshold. The first threshold for the VOC concentration is 0.4 parts per million by volume (ppmv), and the second threshold for the HCHO concentration is 0.1 ppmv. 
     The method may provide soft power cycling comprising rebooting a microprocessor controlling the ionizer wherein the rebooting occurs for several minutes after a fan providing airflow to the ionizer has been operating continuously for more than several hours wherein the rebooting is performed to enhance an ionizer lifetime and clear accumulated errors in the microprocessor memory to improve performance of the microprocessor and the ionizer. 
     The method may include installing at least one air filter upstream of the ionizer where the at least one air filter is selected from the group consisting of: a Minimum Efficiency Reporting Value (MERV) rated air filter with activated carbon, a High Efficiency Particulate Air (HEPA) filter, or the MERV rated air filter with a manganese oxide catalyst wherein the MERV rated air filter with the manganese oxide catalyst is comprised of at least one catalyst selected from the group consisting of: a manganese sulfate or MnSO4 catalyst, a sodium permanganate or NaMnO4 catalyst, and a cryptomelane potassium manganese oxide mineral or K(Mn4+,Mn2+)8O16 catalyst. 
     While the invention herein disclosed has been described by means of specific embodiments and applications thereof, numerous modifications and variations could be made thereto by those skilled in the art without departing from the scope of the invention set forth in the claims.