MOBILE SOURCES:
According to the charts, based on EPA modeling, mobile sources (both on and off-road) contribute 71% of total air emissions in Essex County and 46% of HAP emissions (187 tons per year) in our 3 target communities. Thus, the largest share of air pollution seen in our three target communities is due to on and off road mobile sources.
Motor vehicles emit several pollutants that the EPA classifies as known or probable carcinogens, such as benzene and several others that are considered probable carcinogens such as formaldehyde, diesel particulates, and others. The EPA estimates that mobile (car, truck, and bus) sources of air toxics account for as much as half of all cancers attributed to outdoor sources of air toxics.
These compounds are released in several ways. Some toxic compounds are present in gasoline and are emitted to the air when gasoline evaporates or passes through the engine as unburned fuel. An example of this can be seen with benzene, a component of gasoline. Cars emit small quantities of benzene in unburned fuel, or as vapor when gasoline evaporates. Another source of benzene is the incomplete combustion of compounds in gasoline such as toluene and xylene that are chemically very similar to benzene. Formaldehyde, acetaldehyde, diesel particulate matter, and 1,3-butadiene are not present in fuel but are by-products of incomplete combustion.
While mobile sources were identified as the largest contributor to air pollution in our region, town specific data was limited to EPA’s 1999 estimates provided above. Additional specific data that would further identify target reduction opportunities was not identified, and further study of this category was not conducted as part of this project. This remains a large source that should be studied further and is one of the top priorities identified during this project.
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