Honeywell Response to EPA Questions

on Submitted Exposure Study

EPA Docket: EPA-HQ-OPPT-2008-0918

August 2, 2010

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In response to questions submitted by Audrey Binder on July 7, 2010, Honeywell offers the 

following responses: 

 

The concentration testing provided to the EPA was directly measured by Dr. Chris Seeton at our 

Buffalo Research Laboratory. Dr. Seeton is the primary technical author of SAE J2772 

“Measurement of Passenger Compartment Refrigerant Concentrations under system refrigerant 

leakage conditions” and the testing was done in accordance of SAE J2772, with the exception 

that it was performed outside the vehicle instead of in the interior. R-134a was used in the 

experiments because it has a lower vapor density and when measured in air results in higher 

volume concentrations than an equivalent mass release of HFO-1234yf, thus adding a 

conservative buffer to the experiments. The temperature of the garage was between 18 and 22 

°C and the dew point was between 0 and 10°C; however, humidity is unimportant as it does not 

affect refrigerant concentration testing at percent level concentrations in any way. Dr. Seeton is 

in the process of preparing two peer reviewed journal articles, one documenting the development 

of SAE Standard J2772 (abstract has been submitted and approved for the 2011 SAE World 

Congress, complete manuscript for submission due September 30) and another technical 

publication of scientific quality on using thermal conductivity sensors for precise measurement 

of refrigerant concentrations in air. Dr. Seeton has planned for submission for publication in

mid/late October to a renown measurement methods journal such as Measurement Science and 

Technology or occupational safety journal such as The Open Occupational Health and Safety 

Journal. The 30 day SNUR comment period is simply inadequate for us to have formal peer 

reviewed journal quality documentation but we feel the data we presented is scientifically sound 

and based on industry standard test procedures. 

Concerning the comments addressing acute exposures and TWAs. The EPA SNUR exposure 

assessment addressed only 30 minute TWAs and so we also focused our comments around that 

assumption. EPA did not request or seem to consider shorter TWA exposure scenarios and the 

acute toxicological data simply does not indicate these concentrations for such a short time 

exposures are of concern. 

Charge kit connecting hose lengths are shorter than 6 inches. Our leaks were located at the 

charging port, but leaks at other locations of 6 inch radius from that point would produce similar 

effects due to the close proximity of the can top and the charge port. 

The size of the garage is approximately 20 ft by 30 ft and represents a common two car garage.

We do not understand why the results are “surprising” the Box Model does not account for 

refrigerant buoyancy in air and the ability of a gas to dilute in surrounding gas volumes. Dr. 

Lewandowski cites this fact in the SAE CRP report and in his comment (EPA-HQ-OAR-2008-

0664-0091) that the rationale for using the box model is to determine, using worst-case 

assumptions, if the risk estimates are within acceptable parameters, thus obviating the need for 

more detailed risk characterization efforts. Dr. Lewandowski further advises that if the screening 

model is to be used for other purposes, one should account for the conservativeness of the 

assumptions that form the model. 

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Our intention is to assist the can manufactures in developing safe charging guidelines. Our 

garage air movement was controlled to be quiescent air and not well ventilated. We will assist

small can manufacturers in a manner consistent with our Responsible Care mandate in 

developing their product. 

We feel that there are three classifications of refrigerant container sizes: small cans (12 oz) that 

simply do not contain sufficient material to allow the DIYer to achieve concentration levels of 

concern, intermediate cans sizes (greater than 12 oz but less than 20 pounds) that could be 

acquired by an individual and could generate conditions within the exposure safety margin in 

worst case scenarios, and refrigerant cylinders (greater than 20 pounds) available only to 

qualified service technicians. This is also representative for propane or LPG which can be 

bought at the hardware and sporting goods stores in small containers and at the corner market in 

cylinders greater than 20 pounds. 

We used the term “worker” because of our industry colloquialisms; we agree DIYer is the 

correct term. However, service tools are available for side tapping of small cans for use in 

service shops. 

We are confused by your comments related to the MOE; exceeding a MOE of 30 is the preferred 

direction for safe use, as our testing indicates for the comparison against the box model in Table 

1. 

Further technical questions can be directed to Dr. Seeton’s attention at 

Christopher.Seeton@Honeywell.com. 

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