Outdoor Air Quality

What are hazardous air pollutants?

Hazardous air pollutants (HAPs), or air toxics, are chemicals

EPA lists 188 pollutants or chemicals as HAPs. Examples include heavy metals, such as mercury, cadmium, and chromium, and organic compounds, such as benzene, dioxins, and toluene.

HAPs associated with mobile sources are generally found in similar concentrations in both urban and rural environments. However, across the United States, concentrations of other HAPs are generally higher in urban communities than in rural areas. Concentrations of chemicals such as vinyl chloride, tetrachloroethylene, 1,3-butadiene, and styrene are significantly greater in urban areas than in rural ones. Concentrations of metals, such as mercury, nickel, chromium, and sometimes lead, are also usually greater in urban areas.

Some of the differences in observed chemical concentrations may be because cities have more emissions sources, both stationary and mobile, because rural areas have fewer monitoring sites, or because monitoring sites are placed near urban sources.

What are the sources of hazardous air pollutants?

Nationwide, the greatest sources of HAPs are on-road vehicles, which emit 1,389,111 tons of air toxics/year (according to 1993 data). Vehicles emit known or probable carcinogens such as acetaldehyde, benzene, 1,3-butadiene, formaldehyde, and toluene. The next greatest sources are industries that use commercial and consumer solvents (cleaners), which emit 414,096 tons/year.

This national pattern of emission sources is also found in the Greater Hartford area, where vehicles account for 41% of all sources of HAPs.

For information on some of the stationary source emitters of HAPs, see the EPA's Toxic Release Inventory Data (TRI).

Air quality studies conducted in 1996 showed that the Hartford Landfill did not emit HAPs in concentrations that would pose either short-term or long-term health risks to residents. The Hartford Health Department is currently undertaking a follow-up study on the concentrations of HAPs emitted from the Hartford Landfill.

What are the health effects of hazardous air pollutants?

Hazardous air pollutants can have severe effects on human health. Some cause cancer, while others affect the nervous system, or aggravate asthma  especially in children.

Most HAPs have an acute (immediate) effect only when people are exposed to extremely high concentrations. Such concentrations are almost never found in ambient (outside) air. More commonly, problems result from chronic (long-term) exposure to relatively low concentrations, or cumulative exposure.

Most ambient compounds enter the human body through breathing, although some, such as mercury and PCBs, mainly enter the body through the eating of contaminated food, especially fish. Connecticut now has a statewide fish consumption advisory  for freshwater fish that was issued by the Connecticut Department of Public Health.

Some of the compounds that are typically of concern to citizens are below. It should be noted that the potential health effects, especially cancer, are observed in individuals that have been exposed to concentrations higher than generally found in the ambient air, for very long periods of time.

Many ordinary day-to-day activities contribute to HAPs in the environment. The greatest sources of HAPs in the environment are personal and commercial vehicles. Greater use of public transportation, carpooling, and more fuel-efficient vehicles would help to reduce the amounts of dangerous substances added to the environment.

Open burning of trash and other products and forest fires are the sixth largest producers of HAPs nationally. Reducing the amount of trash through recycling and wise use would help to reduce pollution from municipal waste combustion, power production, and oil and gas production.

Hartford's hazardous air pollutant concerns

Overall

Until recently, Hartford has had few sites in the city where pollutants are monitored. For many years, the Connecticut Department of Environmental Protection used a monitoring site in East Hartford's McAuliffe Park as a reference site, which means DEP used data from East Hartford to estimate Hartford pollution. Since 1998, however, three sites have operated within Hartford.

Hartford compares favorably with other urban areas for concentrations of HAPs in the ambient air, although Hartford levels tend to be higher than those of rural areas. Below is a summary of Hartford data, based upon information from the Hartford Health Department, compared with data from other urban areas.

Selected Air Pollutants in Hartford and Other Urban Areas

Average Concentration in Parts per Billion

 

North Meadows Landfill

Many residents have questioned whether the Hartford Landfill is a source of hazardous pollutants, including hydrogen sulfide. The federal government has studied these questions, and the Hartford Health Department is currently conducting additional research.

In 1994 the Agency for Toxic Substance and Disease Registry (ATSDR) investigated toxic compounds from the landfill. ATSDR found that the Hartford Landfill did not significantly contribute to HAPs in Hartford's North End and did not pose any short-term or long-term health risks to residents.

In June 1997, the ATSDR assessed the amount of sulfur gas at the landfill and in the North End of Hartford. For the complete report, click here.  The agency found that the landfill concentration was 12.5 micrograms per cubic meter, far below the World Health Organization's 24-hour exposure guideline of 150.5 and even farther below OSHA's 8-hour workplace standard of 14,000. Hartford's sulfur level was lower than that of Danbury (20.9 micrograms per cubic meter). Although the Hartford values did represent an offensive odor, they were not likely to trigger asthmatic attacks.

What is being done in Hartford?

There are a number of programs in Hartford and Connecticut that address air toxics. The Connecticut Department of Environmental Protection (CTDEP) and Hartford Health Department (in conjunction with the Environmental Research Institute at the University of Connecticut) are presently monitoring air toxics at three locations within the City of Hartford.

The CTDEP has several programs address emissions from stationary sources, such as the state air toxics control regulation, the Air Toxics Program of the 1990 Clean Air Act Amendments and the air toxics monitoring program. There are programs which address emissions reductions from mobile sources as well as the Small Business Assistance Program. For more information regarding these programs click here.

The CTDEP publishes an annual air quality summary for Connecticut. For a copy of the latest Annual Air Quality Summary click here.

The Connecticut Department of Public Health has a Toxic Hazards Assessment Program (THA) that evaluates the human health risk from exposures to environmental contaminants. For more information on this program click here.