Benzene and the Case for Hazardous Ambient Air Monitoring in Allegheny County

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Hotline, Summer 2001

by Suzanne Seppi, GASP Executive Director

The residents of Allegheny County are fortunate that the Allegheny County Division of Air Quality (ACDAQ) operates an ambient air monitor for benzene in Liberty Borough, recently checked and in good operating order. That Allegheny County has this monitor is a bonus for the local citizens. This type of monitoring is not typical in Pennsylvania. Benzene is a known human carcinogen. It is associated with several forms of leukemia, as well as Hodgkin’s lymphoma and other cancers. Repeated or prolonged exposure to benzene, even at relatively low concentrations, may result in various blood disorders.

Allegheny County has also operated a monitor for benzo(a)pyrene in particulates of a 10-micron size. Around 1983, there were four more County monitors measuring other hazardous substances such as xylene and toluene. Unfortunately, the County’s hazardous substance ambient monitoring as well as monitoring for other air components is on the decline (see article by President Walter Goldburg on page 1 of this Hotline). The benzo(a)pyrene monitor has not operated since 1999 due to laboratory instrument problems according to “Air Quality 2000 Annual Report” of the Allegheny County Health Department.

Do we need hazardous substance ambient monitors? The simple answer in our opinion is yes and more of them. How so? Recently, GASP made the point to the ACDAQ that according to their own Air Quality Report, the annual ambient benzene level in 2000, according to the Liberty monitor, was 3.5 parts per billion (ppb) which is almost as high as it was in 1991. Benzene National Emission Standards for Hazardous Air Pollutants, (NESHAPs) compliance was required for all coke plants by September 1991. These are technical requirements, not ambient standards. USX Clairton Coke, a large industrial facility near Liberty Boro, was in compliance on time; they installed their controls in stages throughout the first nine months of that year. The Liberty site ambient annual average for 1991 was 3.9 ppb. In the intervening years the benzene ambient monitor was slightly less than 2 (ppb) annually typically. The 1-hour maximum in 1999 was 532 ppb and 254 ppb for 2000.

Are these local benzene ambient levels a problem? When they are elevated, we think they are. Unfortunately, as is true with so many toxic substances, there are no county, state or federal ambient standards (but there should be — after all, these are among the most dangerous of substances in the air).

The Texas Natural Resource Conservation Commission (TNRCC) has a 24-hour health effects screening level (HESL) for benzene, which is an average of 4 parts per billion (ppb), a one hour reference level of (25 ppb) and an annual HESL of (1.0 ppb average). TNRCC does ambient monitoring for a variety of volatile organic compounds, including benzene. When these levels are exceeded, especially if it is by a large amount, according to Joanne Wiersema of TNRCC, it’s an alert that there needs to be a timely, more in-depth review. What are levels that might trigger remedial action? For example, in Texas there was concern about a cluster of refinery tank farms and their benzene emissions. “By modeling the six tank farms as a single facility, predicted benzene concentrations in a potential worst-case one-hour scenario were 232 parts per billion, almost sixty times the benzene health effects screening level for short-term exposure (a 24-hour average of 4 ppb). The agency therefore issued enforcement orders for the six companies to add air pollution control equipment and significantly reduce benzene emissions.”1

By the above scenario, those in Liberty and possibly elsewhere in the county should have been concerned about our levels of ambient benzene; after all, our 1-hour maximum in 2000 (254 ppb) was higher than the above mentioned Texas 1-hour level of 232 ppb, and we were much higher here in 1999 (532 ppb). Our annual level in 2000 is also several times higher than the annual level in Texas (HESL).

The Allegheny County Health Department (ACHD) issued a report of their investigation into elevated benzene levels at the May 2001 ACHD Air Quality Advisory Committee Meeting. They noted the largest increases were from spring to fall of 1999 and from summer to fall of 2000, with a large spike in October 2000. The first quarter of 2001 shows a 1.1 ppb average which is a level common in urban areas. There was no definitive explanation reported for the previous elevations.

As to possible contributing factors for the elevated levels, it was speculated at an Air Quality Advisory Committee Sub-Committee meeting that a tar pit at USS Clairton Works was being stirred up to some degree when a wall was being built around it. Later it was confirmed that a cap had been put on the pit starting in September 2000 and finishing in February 2001. The cap involves many layers and is topped by 30 inches of soil. As the increases were strongest in the fall, the problem may yet reappear in 2001 and the source of the problem may not really be known, but the monitor will alert the Air Quality Division to any new benzene spikes.

It is important that ACHD maintains this monitor, but elevations should be addressed and reported upon in as timely a manner as possible. Citizens in the area had noted very bad odors, so there were other indicators besides the monitor readings of air quality problems. Having these elevated levels appear inexplicably after several years of reduced readings demonstrates the importance of careful and continuing monitoring. We encourage the Air Quality Division to expand its hazardous air quality monitoring. There are many suspicions and complaints of odors in other areas of the county such as Neville Island that also have a complex variety of industry emissions. As we go to press, GASP received a not unusual call from the Neville Island area, in this case, McKees Rocks. The complaint referred to the evening of May 6, 2001 around 10:30 when there was a burnt and putrid chemical type smell reported. The caller experienced a burning sensation in her eyes and throat and felt as though she could not breathe. Her visiting friend went home to a different area and had to wash her hair to get rid of the odor. What was it? Was it dangerous? GASP reported this call to ACHD and they will likely look into it, but without monitors it may be hard to determine.

It’s done in Texas and other states; it could be done here. GASP and Clean Water Action, along with citizens in communities surrounding Neville Island, are discussing a proposal for this sort of ambient monitoring on the island with representatives of the Air Quality Division and the Board of Health. It could be funded by the Allegheny County Clean Air Fund. If you think this is an important effort, let the Board of Health hear from you. You may mail the members by writing to: Chair of the Allegheny County Board of Health, Attention: Dr. Roy Titchworth, c/o Allegheny County Health Department, 3333 Forbes Ave., Pittsburgh, PA 15213. Ask that your letter be distributed to the other members.

1. Danger in the Air: Toxic Air Pollution in the Houston-Galveston Corridor Estimating and Monitoring Benzene in Harris County Neil J. Carman, Ph.D.