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March 6, 2001

Mobile County Air Quality

How Do You Assess the Health Impacts of Air Pollutants in Mobile County?

by Edmund Tsang

According to 1996 data, the latest year for which the Alabama Department of Environmental Management (ADEM) has completed an analysis of the various sources of volatile organic chemicals (VOC) in Mobile County's air, automobiles accounted for 25.2 million pounds (16 percent), point sources such as industries accounted for 42.28 million pound (26 percent), and area sources -- those facilities, such as dry cleaners, that are small emitters of VOC compared to point sources -- accounted for 18.39 tons (11 percent). The remaining 47 percent or 76.7 million pounds of VOC are emitted as a result of biogenetic and other natural occurrences in swamps and wetlands of Mobile County.

The health impact of ground-level ozone, of which VOC is a chemical ingredient, is more immediate among the air pollutants found in Mobile County. According to James Hunter, M.D., ozone is "a respiratory irritant and causes damage to the respiratory epithelium or lining cells of the respiratory tract. " Hunter added that "people who have underlying pulmonary problems such as asthma, emphysema, chronic bronchitis or pulmonary fibrosis are more susceptible to the effects of ozone."

Dr. Hunter said air pollution and its effects on respiratory illness is a very complicated problem and one for which it is difficult to get definitive answers. "We all breathe a mixture of gases with variable amounts of contaminating pollutants. At any given time the concentration of these pollutants is different, and we are exposed to both indoor and outdoor air pollution," Dr. Hunter explained. While studies on animals and humans have not consistently shown detrimental effects of short-term exposure to ozone, Dr. Hunter said, "I think that it is generally accepted that ozone is a significant respiratory toxic that can cause increased cough, wheeze and airflow obstruction."

"Here in Mobile, ozone levels are highest and for the last few years have exceeded allowable levels," Dr. Hunter said. "For the last few summers, increasing number of patients have reported to me that they can tell a marked effect on their breathing on high-ozone days. Some of this is due to the power of suggestion from all of the coverage in the media, but too many patients tell me that they can't go outside at all in the summer for it to be a coincidence. We also see increased problems in patients from areas with higher levels of pollution, such as in the Axis/MacIntosh corridor."

"For me, the clincher that [convinced me that] ozone was really playing a significant role in the respiratory problems we see in the community was its effect on the Saint Paul's football team," Dr. Hunter said. "The team was having three practices a day in August last year in the high-ozone period. These are mostly healthy young men in peak physical condition. One of my patient's asthma got so bad from this exposure that he missed attending classes. About half of the team developed a persistent cough like we see in mild asthma, though they were able to continue playing. I am convinced that their prolonged exposure outside at times when ozone levels were highest was the cause of those symptoms."

In addition to the VOC's, 31.98 million pounds (23 percent of total) of nitrous oxide were emitted by automobiles and off-road vehicles in 1996, while point sources due primarily to industries accounted for 102.6 million pounds (73 percent of the total emitted). About one-half of all industrial emissions came from Alabama Power Company's Barry Steam Plant. Furthermore, based on data from the federal Environmental Protection Agency (EPA), 37 million pounds of TRI (Toxic Release Inventory) air pollutants were released into the air of Mobile County in 1996 -- in 1998, the latest year for which the TRI data were available, the amount of TRI air pollutants had decreased to 27.3 million pounds.

Although the amount of TRI air pollutants emitted into Mobile County's air in 1996 was small compared to the total amount of air pollutants -- about 14 percent -- some of these pollutants were detected in concentrations in Prichard during a one-day air sampling in early 1999 that the EPA scientist who analyzed the collected data wrote in the report: "With regard to those chemicals that exceeded a human health-based benchmark, all (with the exception of acetaldehyde) are either chlorinated hydrocarbons or aromatic or aliphatic hydrocarbons." While acknowledging the "caveats" because of limited sampling data, the scientist stated that the data "do provide adequate evidence that a potential threat to public health may exist." [Harbinger, Vol. VIII, No. 5, Nov. 1999.]

Dr. Stephen Schaffer, professor of pharmacology at the University of South Alabama College of Medicine who teaches toxicology, said chlorinated hydrocarbons are "very toxic" and suspected carcinogens, including well-documented studies on carbon tetrachloride, which attacks the liver. While not all aromatic hydrocarbons such as toluene are toxic, other aromatic hydrocarbons such as benzene are highly toxic to humans.

In a telephone interview, Dr. Schaffer said the health impact of TRI air pollutants is "difficult to study." "There are too many parameters to follow," Dr. Schaffer said, "this is especially true when the air pollutants are part of a cumulative assault on human health or when the expose level results in chronic rather than acute conditions." It is easy to diagnose the impact of the toxin due to an acute expose because the effects are "immediate," Dr. Schaffer added. "For chronic exposure, the effects may show up several years or even decades later."

Regarding the health impact of air pollutants, Dr. Hunter said: "Although most physicians are not expert in the area of air pollution and its effects, primary-care physicians should be able to address most of the acute problems caused."


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