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Autobody Shops & Air Pollution

The following is the complete text of a letter from the Phil Wittek of the Johnson County Environmental Department (JCED) describing the study it performed of the aerosol emissions from the two south Johnson County autobody shops. Additional articles about the subject are available under Topics - Auto Body Shops and Air Pollution. In the interests of timely publishing, I used an automated conversion to Internet format (HTML) which has resulted in some formatting errors, particularly with respect to equations. These will be corrected as time permits.

I want to thank Phil Wittek, Mike Boothe, and the Johnson County Environmental Department for the time and effort they have put into this endeavor. I also appreciate being provided an electronic version of the letter which allowed the results to be published in the shortest possible time.


December 16, 1998

 

 

 

 

Mr. Bob Phillips

16315 Dearborn

Stilwell, Kansas 66085

Re: Autobody paint emissions

Dear Mr. Phillips:

This letter contains additional information that you requested in regard to Metcalf Auto Body and Countryside Auto Body and the emissions of lead chromate (PbCrO4) and zinc chromate (ZnCrO4). We have also elaborated on information included in our previous letter.

1. KDHE review of JCED calculations (methodology check)

Our letter to you dated November 12, 1998, contained preliminary calculations concerning emissions from Metcalf Auto Body. We sent our calculations to Mr. David Peter, air permit engineer for the Kansas Department of Health and Environment (KDHE). As was stated in a previous letter to you, both Metcalf Auto Body and Countryside Auto Body are exempt from air quality regulations as their emissions are far below the levels required for a permit. Mr. Peter, however, conducted a review of Metcalf Auto Body at our request applying the same methodology KDHE uses in issuing an air quality permit. The methods used by KDHE were essentially the same as used by the Johnson County Environmental Department (JCED), with one exception. KDHE predicts a source's potential-to-emit by assuming that source operates around the clock, or 8,760 hours per year. The JCED based emissions on a 40-hour work week, or 2080 hours per year.

2. Background on OSHA, NIOSH, ACGIH standards

The Occupational Safety and Health Administration (OSHA), the National Institute for Occupational Safety and Health (NIOSH), and the American Conference of Governmental Industrial Hygienists (ACGIH) have established standards for a variety of chemicals, but there are major differences in the three groups. NIOSH has Recommended Exposure Levels (REL's), while OSHA has the Permissible Exposure Limits (PEL's) expressed as Threshold Limit Values (TLV) and Time-Weighted Averages (TWA). The PEL's adopted by OSHA are enforceable regulations in the workplace (although not every workplace) and are established for the safety of the employees in that workplace. The REL's suggested by NIOSH are only recommended, and are not enforceable. The REL's can and have been adopted into regulation by OSHA in the past, but OSHA can establish a higher or lower TLV than that recommended by NIOSH. OSHA may chose to promulgate the NIOSH recommendations based on satisfying statutory criteria. This would explain the difference between the PEL's and the REL's from the two agencies.

The ACGIH is a non-for-profit, professional organization, not a government agency. ACGIH develops TLV's and Biological Exposure Indices (BEI's) as guidelines for use in the practice of industrial hygiene and worker protection. They are not used for legal standards, as compared to OSHA. It is important to note that the use of ACGIH data is not intended for use in the evaluation or control of air pollution nuisances in estimating the toxic potential of continuous, uninterrupted exposures or other extended work periods. These limits are not fine lines between safe and dangerous concentrations nor are they a relative index of toxicity. The same caution must be applied to the NIOSH and OSHA standards. It's important to note that in 1971, OSHA incorporated AGCIH's 1968 TLV's for nearly all of their PEL's. For your information, and as a comparison, the table below lists the REL's and TLV's for lead (Pb) and chromium (Cr) in milligrams/cubic meter (mg/m3) as currently adopted by each organization.

 

 

Organization

Pb mg/m3

Cr mg/m3

NIOSH

0.100

0.001

OSHA

0.050

0.05

0.10 as chromium oxide

ACGIH

0.050

0.012

Sources: NIOSH Pocket Guide to Chemical Hazards, June 1994;

ACGIH 1998 TLV's and BEI's Treshold Limit Values for

Chemical Substances and Physical Agents, Biological

Exposure Indices

 

3. Lead Chromate TLV/TWA

The ACGIH TLV/TWA's are expressed specifically for lead chromate (PbCrO4) at two different concentrations because there are two metals involved. However, both numbers actually are derived from the undissociated parent compound and one can calculate the metallic portion from the percent composition of the molecular weight. For example, for PbCrO4, the molecular weight is calculated as follows:

Lead = 207

Chromium = 52

Oxygen = 16 x 4 = 64

207+52+64 = 323 molecular weight

The decimal percent of lead is 207 divided by 323 = 0.64

The decimal percent of chromium is 52 divided by 323 = 0.16

 

The adopted ACGIH TLV/TWA level for lead chromate is 0.05 mg/m3 as lead, and 0.012 mg/m3 as chromium. Both of these can be viewed originating from the parent compound at a level of 0.078 mg/m3. If an emission is to take place, it will be of the undissociated lead chromate material which is reflective of lead and chromium. However, one can calculate back to the metal constituents by merely multiplying by the molecular weight decimal percent as shown below:

 

TLV/TWA as PbCrO4 = 0.078 mg/m3 (calculated)

TLV/TWA (as Pb) = 0.078 x 0.64 = 0.05 mg/m3

TLV/TWA (as Cr) = 0.078 x 0.16 = 0.012 mg/m3

Our earlier letter expressed emissions as a factor of the TLV/TWA which would still ring true because it was expressed in terms of lead chromate, not lead or chromium. The factor would still be correct in terms of either metal.

4. JCED 's previous calculations of emissions

In estimating stack emissions from Metcalf Auto Body, a number of assumptions must be made, as we stated in our previous letter. The first assumption involved paint usage. The company uses approximately 300 gallons of paint per year. The first number calculated assumed that all 300 gallons of paint used was the Series 257 Yellow, which contains the highest percentage of lead chromate. However, this number could only be considered reliable if Metcalf Auto Body painted only yellow vehicles, which is certainly not the case, and used only the Series 257 single stage paint system. In retrospect, this should have been further explained in more detail as being illustrative of the methodology or as perhaps completely left out of the discussion.

The second number was made using the actual amount of Series 257 used the company, based on a monthly average of two gallons per month, which is about 8% of their total annual paint usage. While this number is more reliable, it must be kept in mind that when painting a vehicle, the paint is often a combination of several mixing colors. Actual quantities of Series 257 are going to be very small and may vary for each vehicle. This would be similar to tinting house paint and adding small amounts of pigment to achieve a desired final color.

5. Recalculations after methodology check

After checking our methodology with KDHE, recalculations for the lead chromate emissions were performed. It is again necessary to make certain assumptions for these calculations and we have listed them below:

Assumptions:

* Series 257 paint usage = 24 gallons/year.

* Mixing colors usage (those containing PbCrO4) = 2% by weight of series 257

* Average specific gravity = 1.25 g/mL

* Average PbCrO4 content in mixing colors = 27.2%

* Spray gun efficiency = 80%

* Filter capture arrestance = 99.71% and 90%

* Exhaust rate = 10,000 cubic feet/minute = 283.2 m3/minute

* Yearly operations = 2080 hours

 

lbs PbCrO4 usage per year

 

 

1.36 x (1.0-0.8) x (1.0-0.9971) = 0.00079 lbs/year uncontrolled PbCrO4

grams/hour (g/hr) PbCrO4

 

mg/m3 PbCrO4 at exhaust stack

as Pb = 0.0000064 mg/m3

as Cr = 0.0000016 mg/m3

 

 

Using a 90% filter arrestance:

1.36 x (1-0.8)x(1-0.9)= 0.0272 lbs/year uncontrolled PbCrO4

 

g/hr PbCrO4

 

mg/m3 PbCrO4 at exhaust stack

as Pb = 0.00022 mg/m3

as Cr = 0.000056 mg/m3

These calculations show that emissions at the stack are all significantly below the standards given in the table on Page 2.

Please note that two filter arrestance efficiencies were used. The high percentage was based on independent laboratory data from the filter manufacturer and the lower number was included to deal with the variable nature of micron sizing and particle capture.

6. Dispersion modeling

As was mentioned in our previous letter, whatever stack emissions occur are impacted immediately by contact with the outside ambient air. Any dispersion modeling must include elements of atmospheric conditions as they relate to pollutants. Although we do not have a specific computer model detailing the emissions of PbCrO4 as was done for toluene, one can make calculations based on certain assumptions.

Based on the distance from Metcalf Auto Body to the daycare center of approximately 100 meters, volume dilution calculations maybe made at certain degreed arcs. A 45 dispersion arc in one general direction that covers a radius of 100 meters from any point would contain approximately 260,000 m3 of air volume. Assuming that the only dispersion from the stack is caused by the flow of the exhausted stack air, any one hour stack emission would be diluted by a factor of approximately 15 in the 45 dispersion arc.

Another consideration in conjunction with the static dispersion described above would be the added impact of wind velocity. Every mile per hour of wind velocity would equate to about 16 air exchanges per hour over a 100 meter distance. For our general geographic location, the average annual wind velocity is approximately 10 miles per hour, with the average high/low wind speed of 12 and 9 mph. At that average velocity, a 100 meter distance would have over 160 exchanges per hour. This effect would be completely independent of the dispersion arc.

As you know, the Kansas Department of Health and Environment (KDHE) ran a computer model of Metcalf Auto Body's emissions based on an estimated use of toluene. According to KDHE's Dana Morris, who ran the model, fine particulate matter may behave similarly and that some extrapolation of the results could be applied to PbCrO4. Using a direct ratio of evaporative toluene emissions compared to the annual emissions of PbCrO4, the following could be calculated:

If toluene at 0.95 g/sec equates to 1.6 to 2.5 micrograms/m3 at 100 meters, then PbCrO4 at 0.47 x 10-7 g/sec equates to 0.8 to 1.25 x 10-7 micrograms/m3 or @ 1 x 10-10 mg/m3 as PbCrO4 (arrestance at 99.71%).

To put this in perspective, 1 x 10-10mg/m3 would be 1 billion times less than the ACGIH TLV/TWA for both lead and chromium. Comparing the NIOSH recommendation, the factor would be about 50 million times less for chromium. Using the 90% capture arrestance, the dispersion of PbCrO4 would increase by only a factor of 35 based on the calculations on Page 3. In that case, the 1 billion becomes about 30 million.

7. Zinc chromate TLV/TWA

As for the transparent primer that contains ZnCrO4, this is used in very special situations. Metcalf Auto Body only uses about one-half liter per year. Countryside Auto Body uses none of this paint. The calculations of emissions resulting from the use of this primer showed that the annual output would be only about 0.0001% of that calculated for PbCrO4. The result is the same no matter what filter capture efficiency is used. The extremely low amount is due to the minimal use and low ZnCrO4 content. Therefore, this would not make an impact in the calculations involving the series 257 mixing colors containing PbCrO4. The calculations are shown below:

Assumptions:

* Usage = L/yr

* Specific gravity = 0.96 g/ml

* ZnCrO4 <0.1% by weight

* Filter arrestance/capture= 99.71% and 90%

* Spray efficiency= 80%

* Hours of operation = 2080/yr

0.5 x 0.96 x 0.0001=4.8 x 10-4 g/yr ZnCrO4

4.8 x 10-4 x (1-0.8)(1-0.9971)

2.080 x 10-3 = 1.34 10-10 g/hr ZnCrO4

ZnCrO4 1.34 x 10-1

PbCrO4 x 100 = 1.70 x 10-4 x 102 0.0001% (by weight)

 

 

 

 

8. Proprietary information.

In our letter dated November 12, 1998, we attached recently received copies of the Material Safety Data Sheets (MSDS) provided by the paint manufacturer, Spies-Hecker. This was new information from the company, who revised the MSDS at their home office in Germany. These latest MSDS contained information not available in the previous editions of the MSDS supplied to you earlier. This information was supplied by Spies-Hecker and does not represent a legal reversal of our protection of proprietary information as you suggested on your website dated November 16, 1998. JCED has not changed its approach to proprietary information. This was a change made by Spies-Hecker during an update of the information contained in the MSDS and the new information was provided to you as soon as possible. Please note the date of October 10, 1998, on the MSDS.

9. Future rules on auto body paint emissions.

We have made inquiries to Environmental Protection Agency (EPA) for further information on the Maximum Available Control Technology (MACT) rule entitled "Automobile & Light-Duty Truck Surface Coating Operations". This rule is scheduled for implementation on November 10, 2000. David Salman, EPA, Research Triangle Park, North Carolina, has been working on this rule and said it will only address paints used during the vehicle assembly process, such as the Ford Claycomo, Missouri plant and the General Motors site in Kansas City, Kansas. Mr. Salman said that although the paints and coatings used by assembly plants and repair shops may look alike, the paints applied in assembly plants are baked on at higher temperatures before any glass, plastic, or other heat-sensitive materials are added to the vehicle. Paints and coatings used in auto body repair, according to Mr. Salman, are much higher in solvents (which contain volatile organic compounds) than the paints applied at the assembly plants. He said he did not know how the two types of paints compared in terms of hazardous air pollutants. Mr. Salman said that although auto body shops are not currently scheduled for any MACT regulations for their hazardous air pollutant content, it has been discussed by EPA staff and may be addressed in the future.

10. Interviews with Wee Work Shop, Metcalf Auto Body, and Countryside Auto Body.

In our brief interview of Kim Tousey, Director of Wee Work Shop, we asked her in person if she had ever expressed concerns of any kind from parents regarding the emissions from either Metcalf Auto Body or Countryside Auto Body. Ms. Tousey said she had received none. We also asked if she or other staff had any problems stemming from either body shop. She said she had received no complaints from staff.

In a brief interview with Lynn Dewey, owner of Metcalf Auto Body, we asked if anyone from Wee Work Shop or parents of children attending this daycare had complained about emissions from the body shop since they began operations in this location. Ms. Dewey said she had received none.

In a brief interview with Diane Aydukovich, owner of Countryside Auto Body, we asked the same questions. Ms. Aydukovich responded by saying that she had been in this location for seven years and no one had complained on the subject of their emissions. We have also recently visited this shop and discussed their paint usage. While Countryside does use Spies-Hecker paints, they rarely use the Series 257 paint. They did have a small amount of this paint in their inventory, but the single can of mixing color paint was covered with dust from their lack of use. Their painter could not remember the last time it had been used. When it is used, it is used in small quantities of several ounces at a time and is blended with other paint to achieve a specific color. It is also their intention to discontinue use of this paint completely, once the current inventory has been exhausted. Because Countryside very rarely uses the Series 257 paint, no calculations could be made and emissions can be considered negligible.

11. Future rules on hazardous air pollutants.

Also included with this letter is a list of additional MACT standards established by EPA for further information. These standards are established based on the 188 Hazardous Air Pollutants (HAPs) established by the Clean Air Act. These standards are based on the source categories that produce them, rather than by a specific chemical, and will only apply to those specified source categories. Furthermore, to be regulated by these MACT standards, a source must by considered to be a major source of HAPs according to the federal Clean Air Act. To be a major source, it must emit a minimum of 10 tons per year of any one of the listed HAPs, or 25 tons per year of a combination of the listed HAPs. (Neither body shop comes close to approaching these emission levels.) As you can see, some of these standards have already been put into effect.

We believe this letter addresses your concerns about emissions at the two body shops near 162nd and Metcalf. Please call this office if you have any need for further clarification.

Sincerely,

 

 

 

Philip J. Wittek,

Director

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Enclosure

c: Annabeth Surbaugh, Commissioner, 3rd District

Melinda Carlton, County Administrator

Douglas L. Smith, Developmental Services Director

Gary Miller, Section Chief, Bureau of Air and Radiation, KDHE

Richard Tripp, EPA, Region VII

Don Dewey, Metcalf Auto Body

Diane Aydukovich, Countryside Auto Body

Kim Tousey, Wee Work Shop

David Brau, Spies-Hecker

Eileen Hiney, Environmental Services Manager, MARC

Betsy Betros, Director, Pollution Control Division

Mike Boothe, Air Quality Program Manager

 

 


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