The U.S. Environmental Protection Agency provides information on the particulate matter concentration for Allegheny County that have a diameter greater or equal to 2.5 mm. The data is based on a combination of 2012 model and monitor data reported by the U.S. Environmental Protection Agency’s Office of Air and Radiation. The data represents the mean PM 2.5 measurement in micrograms per cubic meter for each census tract in Allegheny County. This data was obtained from the U.S. Department of Environmental Protection’s Environmental Justice Screen tool.
PM 2.5 Estimate
Particulate Matter (PM) affects more people than any other pollutant. The major components of PM are sulfate, nitrates, ammonia, sodium chloride, black carbon, mineral dust and water. It consists of a complex mixture of solid and liquid particles of organic and inorganic substances suspended in the air. The most health-damaging particles are those with a diameter of 10 microns or less, (≤ PM10), which can penetrate and lodge deep inside the lungs. Chronic exposure to particles contributes to the risk of developing cardiovascular and respiratory diseases, as well as of lung cancer.
Air quality measurements are typically reported in terms of daily or annual mean concentrations of PM10 particles per cubic meter of air volume (m3). Routine air quality measurements typically describe such PM concentrations in terms of micrograms per cubic meter (μg/m3). When sufficiently sensitive measurement tools are available, concentrations of fine particles (PM2.5 or smaller), are also reported.
There is a close, quantitative relationship between exposure to high concentrations of small particulates (PM10 and PM2.5) and increased mortality or morbidity, both daily and over time. Conversely, when concentrations of small and fine particulates are reduced, related mortality will also go down – presuming other factors remain the same. This allows policymakers to project the population health improvements that could be expected if particulate air pollution is reduced.
Small particulate pollution have health impacts even at very low concentrations – indeed no threshold has been identified below which no damage to health is observed. Therefore, the WHO 2005 guideline limits aimed to achieve the lowest concentrations of PM possible. For more information, please see the World Health Organization's fact sheet on Ambient (outdoor) air quality and health.