Air Quality Metadata: Particulate Matter (PM2.5)

Origin:

Historical air quality data are from the Maine Department of Environmental Protection's Bureau of Air Quality.

Dates Available:

January 1, 2002 - December 31, 2023

Geographic Resolution:

State

Abstract:

This dataset contains the highest daily average concentration of particulate matter (PM2.5) measured among monitors across the state of Maine. The dataset also contains the corresponding Air Quality Index (AQI) category based on current AQI definitions. Beginning in 2005, a narrative explanation is available for days where the value was at or above the Unhealthy for Sensitive Groups threshold. In addition, a flag indicates a high value attributable to local anomaly (with details in the explanation field).

The dataset contains the following measures:

  1. Daily maximum average concentration of particulate matter (PM2.5) in units of micrograms per cubic meter (ug/m3).
  2. Air Quality Index (AQI) category: Good, Moderate, Unhealthy for Sensitive Groups, Unhealthy, Very Unhealthy, or Hazardous.

Purpose:

This data set supports efforts to improve public health in Maine and contributes to the U.S. CDC’s National Environmental Public Health Tracking (EPHT) Network. A key activity of participants in this network is to track and make available environmental health measures on state and national data portals. Measures derived from the data set described here can be used to compare levels of ambient particulate matter across the state, between groups of people, over time, and in relation to other risk factors, exposures, and health outcomes.

The Maine Tracking Network, a member of the National EPHT Network, connects communities, public health professionals, policy makers, state agencies, and others to the data they need to monitor public health, respond to health concerns, prioritize resources for public health action, and evaluate prevention activities. Maine tracks certain health effects, exposures, and environmental hazards that have known relationships, as well as some health effects and environmental hazards that have suspected relationships. By making health and environmental data available through the Maine Tracking Network, more people have access to data they need to think critically and hypothesize about health outcomes and their relationships to conditions in the environment.

Supplemental Information:

Particle pollution, or particulate matter, consists of particles that are in the air, including dust, dirt, soot and smoke, and little drops of liquid. Some particles, such as soot or smoke, are large or dark enough to be seen. Other particles are so small that you cannot see them.

Particle pollution can come from primary or secondary sources. A primary source, such as wood stoves or forest fires, lets off particle pollution directly. A secondary source lets off gases that react and form particles. Examples of secondary sources are coal fires and power plants. Particle pollution also comes from motor vehicles, factories, and construction sites. These can be primary or secondary sources. Particle pollution can be a problem at different times of the year, depending on where you live.

Particle pollution includes:

  • coarse particles that are between 2.5 and 10 micrometers,
  • fine particles that are between 0.1 micrometers and 2.5 micrometers; also known as PM2.5, and
  • ultrafine particles that are smaller than 0.1 micrometers.

Particles bigger than 10 micrometers can irritate your eyes, nose, and throat but do not usually reach your lungs. Ten micrometers is about seven times thinner than one human hair.

Fine and ultrafine particles are the most concerning because they are most likely to cause health problems. Their small size allows them to get into the deep part of your lungs and even into your blood.

Air Quality Index categories correspond to the following PM2.5 concentration ranges, measured in micrograms per cubic meter: Good, 0 - 9.0; Moderate, 9.1 - 35.4; Unhealthy for Sensitive Groups, 35.5 - 55.4; Unhealthy, 55.5 - 125.4; Very Unhealthy, 125.5 - 255.4; or Hazardous, ≥255.5.

Entity and Attribute Overview:

This dataset includes: date, concentration of particulate matter (PM2.5) in micrograms per cubic meter, AQI Category, flag indicating a high value attributable to local anomaly, and narrative explanation (for values since 2005 at or above AQI Category "Unhealthy for Sensitive Groups"). 

Data Limitations:

  • The measure can provide a general indication of the overall trend in particulate matter (PM2.5) concentrations - both seasonally and over the long term. It does not directly assess individual or population exposures. The relationship between ambient concentrations and individual exposure is subject to many factors, including individual activity patterns and microenvironments.
  • Air monitors provide concentration data around the specific location of each monitor. Comparing maximum values statewide on different days may not reliably indicate differences in average levels across the state as a whole, nor differences in average exposure levels among the population. 
  • There is no stored attribute indicating the monitor location where the maximum value occurred.
  • The Air Quality Index does not account for additive or synergistic effects of multiple pollutants together.

Access Constraints:

None.

More Information:

Suggested Citation for Data Displays:

Maine Center for Disease Control and Prevention, Maine Tracking Network. Air Quality (Historical): Particulate Matter (PM2.5). Available online: https://data.mainepublichealth.gov/tracking/. Accessed on [Date].