WHAT ACTIVITIES CAUSE AIR POLLUTION? WHERE DOES AIR POLLUTION COME FROM?
Most sources of air toxics are human-made. They usually derive from either mobile or stationary sources.
When we look at air toxins at the community level, they come from either background sources, mobile sources, or stationary sources. Stationary Sources (also referred to as Point sources) can be broken down into Area and Major sources.
Definitions:
Background sources, such as mid-western power plant pollution, come from other places, transported by wind. Or they are a result of historic use that remains persistent in the environment, not necessarily created by human activity.
Mobile sources include both on-road vehicles and off-road equipment such as trains, planes, ships, agricultural equipment including landscape machinery, and construction equipment.
While each vehicle and piece of equipment make a small contribution as a single source, collectively, mobile sources contribute significantly to air pollution, especially in urban areas where motor vehicles emit significant amounts of the carcinogen benzene as well as carbon monoxide, hydrocarbon, and nitrogen oxide pollutants.
STATIONARY SOURCES:
Area sources are stationary sources that are either too small or too numerous to assess individually. According to EPA, Area sources are defined as sources that are not included in the Major source category. In otherwords, sources that emit less than 1 ton/yr in MA or 10 tons /yr under EPA definitions. This category is primarily residential, commercial, and small industrial facilities.
Examples of area sources include dry cleaners, gas stations, small print shops, auto-body shops, electroplaters, and furniture manufacturers. Area sources also include consumer products in homes and offices, such as cleaners, pesticides, paints, and glues. Even though emissions from each individual area source may be small, their collective emissions can create significant health risks, particularly where there are large numbers of area sources located in a small geographic area, or when they are located in highly populated areas.
Major sources are major industrial facilities including power plants that emit enough pollutants (10 tons per year of any one of the 188 listed hazardous air pollutants, or 25 tons per year of a mixture of air toxics ) to be required to report under the Clean Air Act.
Examples of major sources include chemical plants, paper mills, large printing and coating operations, power plants, and waste incinerators. These sources can release air toxics through stacks and vents, fugitive process emissions, equipment leaks during material transfer and handling, or accidental releases.
WHAT WE STUDIED:
While realizing that both Mobile and Background sources of air pollution make up a significant portion of the air pollution picture, the North Shore AIR project decided to focus on those sources that could be more easily defined and reviewed by a local organization. Mobile sources are difficult to determine without doing traffic studies and major air pollution modeling, and background sources are not something within the communities' control and therefore are less valuable to study for potential reduction opportunities.
Thus, the focus of this project was to further understand and define Area Sources and Major Sources. For Area Sources, publicly available data was collected and reviewed, and community volunteers participated by physically locating a selection of area sources that could be defined. For Major Sources, publicly available data was collected and reviewed to further the understanding of this category’s contribution to air pollution, specifically in Essex County and the three target communities.
