U.S. CONSUMER PRODUC T SAFETY COMMISSION
4330 EAST WEST HIGHW AY BETHESDA, MD 20814

January 14 , 2014

Ms. Diana Pap pas Jordan
Chair of STP 2201
Underwriters Laboratories Inc. 333 Pfingsten Road Northbrook, IL 60062

RE : CPSC Staff Request for Formation of a Working Group and Staff’s Recommendations for Requirements to Address the Carbon Monoxide Poisoning Hazard Associated with Portable

Generators

Dear Ms. Jordan :

U.S. Consumer Product Safety Commission (CPSC , Commission ) staff requests that Underwri ters Laboratories Inc. (UL) form a working group to develop specific proposals for requirements for portable engine

- generator sets that fall under the scope of UL 2201

, Portable Engine

- Generator
Assemblies to reduce the risk of death and injury due to carb on monoxide ( CO ) poisoning

. a Since first joining the Standards Technical P anel (S TP) for UL 2201 in 2002

, CPSC staff has advocated that the

STP adopt requirements in the standard to address the rising number of generator

- related CO poisoning fatalities

. Over the last few years, as part of the agency’s rulemaking project to address this

hazard

, b CPSC staff has worked to demonstrate the feasibility of lowering engine CO emission rates

. Th e results of this technical work conducted by and for the CPSC provid e the solid foundation for

staff’s rationale and recommendations summarized herein for a framework of performance requirements and corresponding test methods that a working group can use as a starting point to develop specific proposals for consideration b y the STP.

M odifying UL 2201 to include CO emission rate limits would address the source of the hazard and make a direct impact on reducing the risk of CO poisoning death and injury associated with the use of portable generators

. c Despite sustained i nformation and education efforts by the CPSC and many

other stakeholders to promote public awareness of the generator

- related CO hazard , especially before

a These comments are those of CPSC staff, and they have not been reviewed or approved by, and may not necessarily reflect the views of, the Commission.

b Portable Generators; Advance Notice of P roposed Rulemaking; Request for Comments and Information

, Federal Register, 71 FR 74472, December 12, 2006. CPSC staff is in the process of developing a draft notice of proposed rulemaking for the

Commission ’s consideration.

c Examples of reducing engin e exhaust CO emission rate s as the means to reduce CO deaths and injuries include forklifts and other equipment used in enclosed areas as well as the engines that power marine generators

. Furthermore, when catalytic

converters were put on automobile engin es beginning in 1975 to meet EPA emission standards , it resulted in a reduction of

unintentional vehicle

- related CO deaths of greater than 80% in the years of 1975 through 1996 compared to earlier years. 1
(Superscripted numbers refer to references listed at the end of this letter.)2

and after major storms

, the death toll continues to rise

. The increase in fatalities has continued e ven since 2007, when CPSC mandated a hazard label

. 2 A ccording to the CPSC’s data

, for the 14

- year period from 1999 through 2012

, there have been at least 800 c onsumer generator

- related CO poisoning

fatalities

. d

, 3 In addition, in CPSC staff’s most recent r eport on non

- fire CO deaths a ssociate d with use of consumer products, which provides annual estimates through 2009, generators have overtaken the entire product category of heating systems (including furnaces, portable heaters, and space heaters) to
become the consumer product responsible for the largest estimated number of annual non

- fire

- related
CO deaths since 2005. 4

CPSC s taff recommends a single performance requirement and corresponding test method that sets
a limit on the engine’s exhaust CO emissio n rate to a level that is technically achievable and will modify the consequent CO exposure profiles to delay progression of CO poisoning symptoms compared to existing genera tors when operated in an enclosed space. e This will give exposed
occupants more t ime to recognize that a hazardous situation is developing

. This , in turn, will allow
occupants greater opportunity to leave the exposure or to take actions that could result in their rescue before becoming incapacitated

. To assist in the development of a basis for this requirement, CPSC engaged the National Institute of Standards and Technology (NIST) to perform tests on a n unmodified,

carbureted 5 kilowatt (kW) generator operating in the attached garage of a single

- family home to
measure the accumulation of CO in the garage and tran s port through out the house. Using the closed
garage test data (a common fatal scenario), C PSC staff performed health effects modeling on the ensuing CO exposures , which p redict s that occupants in the house and garage would hav e little time to perceive CO poisoning symptoms before the extremely quick onset of incapacitation and ultimately

death

. 5 Consequently , f or this requirement, CPSC staff is currently considering an exhaust CO

emission rate limit in the range of 100 to 150 grams per hour (g/hr) as the oxygen (O 2 ) level in the intake air drops below ambient (20.9%) . Oxygen depletion occurs when a generator is operated in an enclosed space and this can be an important factor in engine CO production

.

S taff’s analysis to dete rmine the appropriate limit to recommend is ongoing ; however, staff notes

that staff’s proto type reduced

- CO emission 5 kW portable generator emitted CO nominally at

, or below 100 g/hr

, and no trend toward higher emission rates was seen as the oxygen level dropped. 5,7

This reduced CO emission rate was accomplished by retrofitting a closed

- loop electronic fuel injection
system , an O 2 sensor, and a catalyst onto the carbureted 5 kW generator

. In contrast, NIST’s tests
showed that t he carbureted unit emitted C O at rates from a low of nominally 500 g/h r near ambient O 2

, to a high of nearly 4

, 000 g/h r as O 2 decreased to 17 percent

. Using data from when NIST tested the prototype in the same attached closed garage scenario, CPSC staff’s health effects modeling pred ict s that the garage occupant would experience a twelve

- fold delay in progression of CO poisoning
symptoms compared to the carbureted unit (96 minutes instead of 8 minutes for the time interval between predicted obvious symptom onset and incapacitation)

.

While CPSC staff is working w ith NIST in perform ing analyses to r efine the details of possible requirements

, staff offers the following general description of recommendations for a test procedure to
determine the generator CO emission rate as the intake O 2 level drops :

After situating the generator in a test chamber with air in the chamber initially set at approximately 68 o F, 40% relative humidity, and ambient CO concentrations

, s tart the generator

d This count is based on 597 incidents entered into CPSC’s databases as of April 23, 2013

.

e When the incident location was identified in CPSC’s investigation report of an incident, more than 95 percent of the

incidents occur red when the generator was operated in an enclosed space.3

and apply a continuous resistive load to one of the gene rator’s receptacle s

. Operate the generator for at least 30 minutes and continue until either the chamber O 2 drops to 16%

, or the chamber O 2 reaches steady state above 16% while the generator’s delivered power decrease s to no more than
60% o f the output me asured at the beginning of the test

. While the generator is operating, record
the chamber CO and O 2 concentration s and the generator output power at least once per minute

. Using the CO concentr ation data, the chamber’s air change rate, and the chamber vo lume,

c alculate t he CO emission rate for each 5 minute interval with the load applied

. Perform this test with each of the following three loads applie d: the maximum load the generator will sustain without tripping its c ircuit breaker ( this is defined as f ull load) , 50% of full load, and 25% of full
load

. T o successfully meet the performance requirement, t he CO emission rate s at all three loads

, calculated as the O 2 drops

, must not exceed the emission limit, for which staff is currently considering a value in the range of 100 to 150 g/hr

. T he chamber volume and its range of
achievable air change rates should be sized by the manufacturer according to the engine’s O 2 consumption rate s while operating under 25% load and full load for the size range of generat ors they e xpect to test

.

It is possible that a n exception to this performance requirement could be made to accommodate
alternative approaches suggested in public comments on the s taff’s technical report on the prototype
generator. 6 Some comment ers opined that a shutof f system , particularly one using a CO sensor, should

be used as the means to reduce deaths and injuries ( i.e.

, one that would shut off the engine before it

creates an unsafe CO exposure )

. f It is important to note that although staff investigat ed four different approaches for a shutoff system

, including two that used CO sensors, staff was not able to demonstrate fully how a shutoff system could be implemented satisfactorily.

Accordingly, the working group should consider whether a generator equ ipped with an automated engine shutoff may be permitted to exceed the CO emission rate limit that staff is currently considering (in the range of 100 to 150 g/hr ) when the O 2 is below ambient O 2 if all of the following
three conditions are met:

1. The exhau st CO emission rate does not exceed the rate limit of 300 g/hr at ambient O 2 (20.9%) when full, 50%, and 25% loads, as defined above, are applied to the generator

. This is expected to address the outdoor use scenario where not all of the exhaust from a gen erator operating outdoors at normal ambient O 2 enters the building to create the occupants’ CO

exposure profiles

. This requirement is intended to provide t hose consumer s who explicitly try

to follow manufacturers ’ instruct ions with the same increased time interval to recognize a hazardous situation is developing and, correspondingly, the same increased opportunity for escape as those who use the generator in an enclosed space

. g S taff’s analysis of the appropriate

f It is worth noting that the approach of a CO

- sens ing shutoff system was considered for a while by some stakeholders as a possible means to address CO deaths and injuries that were occurring on and around recreational boats due to the marine
generator engine’s exhaust . Because the engine is fixed in the boat

, and the locations where the exhaust can infiltrate are

known , this seemed to be a straightforward solution; however, all the primary stakehol ders, including the National Institute for Occupational Safety and Health (NIOSH), the U.S. Coast Guard (USCG), the U.S. Environmental Protection Agency (EPA), engine manufacturers, and the boating industry, agreed that “one of the best approaches to CO co ntrol would be to

reduce it at the source.” 9 These stakeholders rejected use of a CO

- sensing shutoff system to address the hazard , citing that “Houseboats and other cabin boats are generally fitted with CO detectors

. . . often when the CO detectors do al arm, users tend to believe that they are malfunctioning because they do not smell gas. In the case where the alarm goes off frequently, the user may just disconnect the CO detector, even if it has been operating correctly.” 9 As a result, the engine manufa cturers voluntarily developed low CO emission engines rather than using a shutoff system

.

g Some manufacturers recommend, or sell with the generator, extension cords 15 or 20 feet long. Almost all manufacturers also recommend that generators be placed under cover when it is wet outside because, although these products are intended4

limit is ongoing; however, at this time, 3 00 g/hr is s taff’s recommendation for this requirement

. Staff is refining the details for a test method that uses a constant

- volume sampling (CVS) or

raw exhaust emission measurement system to determine the generator’s emission rate with

each of the three loads applied to the generator at ambient O 2

.

2. When operated in a test chamber, the generator shuts off before the engine emit s approximately 25 grams of CO

. This is expected to protect the occupants who take no protective action and remain in the cons equent CO exposure profiles against serious or lasting
adverse health effects when the generator is operated in an enclosed space

. 8 Although s taff’s analysis of this is ongoing, s taff is not currently considering recommending a limit lower than

this

. T he corresponding test method to verify the amount of CO emitted c ould be performed in

a chamber (not necessarily the one described above) and the amount of CO would be

calculated from the air change rate , chamber volume, and analysis of the CO concentration

d ata . W hat must be defined further for this test method

, however, are the environmental

conditions that should be set for the chamber test and the state of condition ing the shutoff
system on the generator should be in when tested. The shutoff system must be durable and work throughout the generator’s operational life

, without calibration or service, so designs

must consider the wide variety of environments in which consumers use their generators and store them during prolonged non

- use periods

.

Depending on the technology employed for the shutoff system

, b oth the usage and storage environments can pose significant challenges to the durability and reliability of the sensor and control components

. For instance, between uses a consumer may store a generator for years in

a garage , exposing the shutoff system to extreme temperatures and humidity as well as a

multitude of contaminants (e.g. vapors and particulates) that could contaminate a sensor. Further, when the generator is in use , the shutoff system will be exposed to the engine’s exhaust, heat, and vibration as well as the extreme winter and summer ambient conditions
which cause power outages that motivate consumer s to use generator s

. I t is important to note

that CO sensor s used in residential CO alarms are not designed for use in such extreme
environments and CO sensors that may be more durable and used in commercial or industrial settings require periodic professional maintenance and calibration. T he test method used to verify a shutoff’s performance m ust account for these and other conditions that the shutoff

for outdoor use only, they are not weatherized for safe use in wet conditions where they can present a risk of shock or

electrocution. Staff believes these recommendations ca n put the consumer at serious risk of exposure to the CO hazard

because the recommendations may encourage generator operation in close proximity to a residence or an enclosed environment. During extended power outages in particular, homeowners experience a sense of urgency for basic needs, such

as heat and food refrigeration; yet the power cord on many home appliances commonly is not long enough to reach windows or other openings where the consumer could connect the appliance to a 15

- or 20

- foot extension cord and be able at the same time to locate the generator far away from the opening. Although only a limited number of deaths in CPSC databases are

attributed to exhaust entering the house from outdoor generator use, it is important to note that CPSC does not count or
estimat e CO injuries

, but the CPSC databases do have records of such injuries. There are other published sources that show injuries from outdoor operation as well

, and a number of these sources document that the injured consumers used their generators an average of only a few feet away from the nearest door or window

. In 2013, the Centers for Disease Control and Prevention (CDC) began recommending that generators should never be placed less than 20 feet from an open window, door,

or vent whe re exhaust can vent into an enclosed area. This recommendation is based on results of modeling studies performed by NIST o n the e ffects of operating an existing, carbureted generator outdoors on i ndoor CO concentration profiles. To put the CO emission ra te of an existing generator into perspective relative to a car , the unmodified carbureted 5 kW portable generator, when operating at ambient O 2 (20.9%), has a CO emission rate that is over 200 times more than that of an idling 1996 Oldsmobile Cutlass. 1 0 T hat factor increases to more than 1

, 500 times greater when the generator is operating in an enclosed space.6

References

1. Mott

, J

. A

. , et al., National Vehicle Emissions Policies and Practices and Declining US Carbon

Monoxide

- Related Mortality

, Journal o f the American Medical Association, 288 (8) : 988

- 995

, August
2002.

2. 16 CFR part 1407, Portable Generators; Final Rule; Labeling Requirements , Federal Register, 72 FR 1443, January 12, 2007, and 72 FR 2184, January 18, 2007.

3. Hnatov, Matthew, Incidents, Dea ths, and In

- Depth Investigations Associated with Non

- Fire Carbon Monoxide from Engine

- Driven Generators and Other Engine

- Driven Tools, 1999

- 2012 , U.S. Consumer Product Safety Commission, Bethesda, MD, August 2013 ( Docket Iden tification CPSC

2006

- 0057

- 0016, available online at www.regulations.gov ).

4. Hnatov, Matthew, Non

- Fire Carbon Monoxide Deaths Associated with the Use of Consumer Products, 2009 Annual Estimates , U.S. Consumer Product Safety Commission, Bethesda, MD, December 2012. (Docket Ide ntification CPSC

- 2006

- 0057

- 0013, available online at www.regulations.gov ).

5. CPSC staff report, Technology Demonstration of a Prototype Low Carbon Monoxide Emission
Portable Generato r , U.S. Consumer Product Safety Commission, Bethesda, MD

, August 6, 2012. (Docket Identification CPSC

- 2006

- 0057

- 0002, available online at www.regulations.gov ).

6. Public comments on CPSC Staff Report Technology Dem onstration of Prototype Low Carbon
Monoxide Emission Portable Generator

– dated September 14, 2012, U.S. Consumer Product Safety Commission, Bethesda, MD

, (Docket Identification CPSC

- 2006

- 0057

- 0004 available online at www.regulations.gov ).

7. S. J. Emmerich, A. K. Persily, and L. Wang, Modeling and Measuring the Effects of Portable
Gasoline Powered Generator Exhaust on Indoor Carbon Monoxide Level (NIST Technical Note 1781), Feb 2013. (Docket Identification CPSC

- 2006

- 0057

- 0005, available online at www.regulations.gov ).

8. A. K. Persily, et al., Residential Carbon Monoxide Exposure due to Indoor Generator Operation: Effects of Source Location and Emission Rate (NIST Technical No te 1782), June 2013. (Docket
Identification CPSC

- 2006

- 0057

- 0012, available online at www.regulations.gov ).

9. Samulski, Mike, Summary of Government/Industry Carbon Monoxide Workshop and Two Follow

Up Meetings , Marc h 31, 2004, (Docket Identification EPA

- HQ

- OAR

- 0008

- 0008, available online at www.regulations.gov ).

10. Frey, H., et al., On

- Road Measurement of Vehicle Tailpipe Emissions Using a Portable Instrument

, Journal of the A ir & Waste Management Association, Vol.53, August 2003.