Influence of Indoor Air Filtration Strategies on Occupant Health Indicators

Study Overview
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Brief Summary
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The purpose of this study is to evaluate whether two different central air purification technologies reduce air pollutant exposure and beneficially influence health as evaluated with a suite of biological markers related to cardiovascular and respiratory disease risk.

Detailed Description
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This study will test two common types of central air handling unit filtration technologies, high-efficiency particulate air (HEPA) filters and electrostatic precipitators (ESPs), to evaluate the impacts of these technologies on personal exposure to air pollutants and the associated cardiovascular and respiratory health outcomes. HEPA filters remove a high percentage of the particulate matter in the air, as do ESPs, but ESPs also generate ozone, which may have its own detrimental health effects. These air purification technologies will be placed in different combinations with a coarse pre-filter to protect the air exchange machinery (combinations: pre-filter only, pre-filter + HEPA, and pre-filter + HEPA + ESP) in both the residences and offices of study participants living on a factory campus in Changsha, Hunan Province, China. Large dormitories and office buildings with central air handling units are common in China and around the world, and so adding air purification into the central ducts represents a practical strategy to reducing personal exposure to air pollution and related health outcomes. The Changsha area commonly suffers from high air pollution, and the dormitories and offices on this workspace are already outfitted with both HEPA filters and ESPs. Therefore, testing these technologies in this environment presents a natural experimental condition to test the benefits of air purification. The study investigators hypothesize that both the pre-filter + HEPA and pre-filter + HEPA + ESP conditions will reduce particulate matter exposure and reduce biological markers of cardiovascular and respiratory disease compared to the pre-filter alone, but that the ESP will generate enough ozone to lead to lower health benefits than HEPA+pre-filter condition.

Official Title
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Influence of Indoor Air Filtration Strategies on Occupant Health Indicators

Conditions
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Risk Factors for Respiratory and Cardiovascular Disease

Intervention / Treatment
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* Device: Central air handling unit air purification technologies


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Healthy adults; Live and work at the Broad Town work campus in eastern Changsha, Hunan Province, China Exclusion Criteria: Has any of the following diseases: chronic respiratory, cardiovascular, liver, renal, hematological disease; diabetes mellitus; Has any other diseases that may confound or complicate the effects of the intervention Pregnant females

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Group A: Pre-Filter Only Intervention<br>Subjects in Group A start with baseline conditions of pre-filter + HEPA + ESP in their offices and dorms. After a baseline biological measurement, they then receive a 5-week intervention in which both the HEPA and ESP are removed, leaving only a pre-filter. This intervention period includes a biological measurement 2 weeks into the intervention and other 4-5 weeks into the intervention. The baseline air purification conditions are then restored, and another biological measurement is taken 2 weeks after that. | Device: Central air handling unit air purification technologies<br>* As described in the arm descriptions, the interventions involve changing the baseline pre-filter + HEPA + ESP conditions by removing either just the ESP or both the ESP and the HEPA for a five week period.<br>* Other names: Electrostatic precipitator (ESP);|
| Active Comparator: Group B: Pre-filter + HEPA Intervention<br>Subjects in Group B start with baseline conditions of pre-filter + HEPA + ESP in their offices and dorms. After a baseline biological measurement, they then receive a 5-week intervention in which the ESP is removed, leaving a pre-filter + HEPA combination. This intervention period includes a biological measurement 2 weeks into the intervention and other 4-5 weeks into the intervention. The baseline air purification conditions are then restored, and another biological measurement is taken 2 weeks after that. | Device: Central air handling unit air purification technologies<br>* As described in the arm descriptions, the interventions involve changing the baseline pre-filter + HEPA + ESP conditions by removing either just the ESP or both the ESP and the HEPA for a five week period.<br>* Other names: Electrostatic precipitator (ESP);|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline FEV1 | FEV1 (forced expiratory volume in the first second of exhalation, unit: liter) was measured by spirometry in all subjects at four separate time points to compare FEV1 changes at different times before, during, and after the filtration intervention as a marker of lung function. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline soluble P-selectin | Soluble P-selectin (a protein shed by activated platelets in the blood, unit: ng/ml) was measured by ELISA in plasma in all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of platelet activation. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline von Willebrand factor (VWF) | VWF (a glycoprotein released by damaged vascular cells into the blood, unit: ug/ml) was measured by ELISA in plasma in all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of endothelial cell damage. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline augmentation index (AI) | AI (a measure of how much the reflecting pulse wave augments the outgoing systole pulse wave, unit: N/A (index)) was measured by pulse wave analysis in all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of arterial stiffness. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline systolic blood pressure (SBP) | Brachial SBP (unit: mm Hg) was measured by an oscillometric method in all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of vasoconstriction. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline fractional exhaled nitric oxide (FeNO) | FeNO (produced from inflammatory nitric oxide signalling in the lung, unit: ppb) was measured with an ambient NO-scrubbing collection method and chemiluminescence in all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of airway inflammation. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change from baseline C-reactive protein (CRP) | CRP (an inflammatory protein in the blood, unit: ng/ml) was measured with an ELISA in blood samples for all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of systemic inflammation. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline 8-hydroxy-2'-deoxyguanosine (8-OHdG) | 8-OHdG (a product of DNA oxidation found in the urine, unit: ng/ml) was measured with LC-MS in urine samples for all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of systemic oxidative stress. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline exhaled breath condensate malondialdehyde (EBC MDA) | EBC MDA (a product of lipid oxidation found in the exhaled breath, unit: nM) was measured with HPLC in exhaled breath condensate samples for all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of airway oxidative stress. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline exhaled breath condensate nitrite + nitrate (EBCNN) | EBCNN (a product of airway inflammatory NO signaling found in the exhaled breath, unit: uM) was measured with HPLC in exhaled breath condensate samples for all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of airway inflammation. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline exhaled breath condensate pH (EBC pH) | EBC pH (a characteristic of exhaled breath associated with inflammation, unit: pH) was measured with a pH meter in exhaled breath condensate samples for all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of airway inflammation. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline diastolic blood pressure (DBP) | DBP (unit: mm Hg) was measured with an oscillometric method for all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of vasoconstriction. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 
| Change from baseline forced vital capacity (FVC) | FVC (unit: liter) was measured with spirometry for all subjects at four separate time points to compare levels at different times before, during, and after the filtration intervention as a marker of airway function. | At baseline, 2 weeks and 4 weeks into the intervention period, and then 2 weeks post-intervention | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Air Pollution, Air Filtration, Exposure Assessment, HEPA Filter, Electrostatic Precipitator, Cardiovascular Disease Biomarkers, Respiratory Disease Biomarkers