Particulate matter (PM) makes up the mixture of solid particles and liquid droplets found in the air contributing to air pollution. PM can be emitted directly from a variety of sources, such as construction sites, unpaved roads, fields, and fires. Other sources of PM include industrial facilities, and power plant facilities as well as secondary sources from nitrogen oxides (NOx) and sulfur dioxide (SO2). PM can form in the atmosphere due to reactions of chemicals such as sulfur dioxide and nitrogen oxides. PM levels in the air are regularly monitored by health agencies.
PM2.5 refers to fine inhabitable particles, with diameters that are generally 2.5 micrometers and smaller. PM2.5 is a particularly important factor contributing to reduced air quality negatively impacting respiratory health especially among senstive populations such as seniors. PM2.5 concentration is measured as the annual average in units of micrograms per cubic meter of air (µg/m3). The smaller the particle size the greater the potential health problems, due to their potential to get deep into the lungs and bloodstream. One’s lungs and heart can be negatively affected by PM, especially if they have pre-existing related diseases, or are child or older adults. These impacts include experiencing:
- premature death in people with heart or lung disease;
- decreased lung function; and
- increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing.
Estimates are based on public monitoring data using the Community Multi-scale Air Quality (CMAQ) data. Census tract estimates for modeled O3 concentration were based on 2013 monitoring data and were assigned to Census block groups. A limited number of U.S. air quality monitors have suitable data, so modeled estimates are required to provide national coverage using a Bayesian space-time downscaling fusion model appraoch 1 PM2.5 concentration is measured as the annual average in units of micrograms per cubic meter of air (µg/m3).
- PM2.5 concentration = monitoring and modeled annual average estimates of the amount of PM2.5 in air (µg/m3).
The MSA level value is the unweighted mean of the values of all block groups in the MSA.
This indicator was calculated by U.S. Environmental Protect Agency (EPA) using data from the sources listed below.
- U.S. EPA, Environmental Justice (EJ) Screen, 2016.
- U.S. EPA, Office of Air and Radiation (OAR) fusion of model and monitor data, 2012.
Fann, N., Lamson, A. D., Anenberg, S. C., Wesson, K., Risley, D., & Hubbell, B. J. (2012). Estimating the National Public Health Burden Associated with Exposure to Ambient PM2.5 and Ozone. Risk Analysis, 32(1), 81-95.