Ambient Air

particulate matter   •   sulfur dioxide   •   ozone


The Clean Air Act requires that the EPA must designate National Ambient Air Quality Standards (NAAQS) for outdoor air pollutants that may be harmful to human health and/or the environment. The NAQQS set the maximum level of a given air pollutant that should be in the air. Our goal is to be at or below these standards. These air pollutants can originate in many obovious ways such as automobiles, power plants, combustion of fossil fuels, and manufacturing. Some other activities that add air pollution may not seem as obvious are: filling up our gas tanks, mowing the lawn with gasoline powered mowers, using a dry cleaning service, and even painting.

Ambient air quality monitoring

One of ARAQMD’s primoary duties is to monitor outdoor air quality for Medina, Portage, and Summit counties and to ensure that our air meets the NAAQS. The criteria pollutants ARAQMD currently monitors for are ozone (March-October), PM2.5,and sulfur dioxide. Originally it was also necessary to monitorfor lead, carbon monoxide, and PM10, but levels of these have been well below the national standards so they are not presently being monitored.

The criteria pollutants are monitored through the use of multiple monitors specifically designed to analyze each specific pollutant. These monitors collect samples to determine the concentrations of the criteria pollutants. The concentration values are then compared to the standard to determine if air quality standards are being met. There are three types of monitors, continuous, intermittent, and speciation:

  • Continuous monitors collect data every day for a 24 hr. period and is downloaded at 8 A.M. and 4 P.M. to an EPA server. The criteria pollutants continuously analyzed are ozone, PM2.5, and sulfur dioxide.
  • Intermittent monitors run every third day for a 24 hour period from 12 midnight to 12 midnight. Particulate matter (PM2.5 and PM10) is manually collected from a filter, weighed, and sent for further analysis. 
  • Speciation monitors run every 6th day for a 24 hour period from midnight to midnight. Data is manually accessed at these monitors and then sent for further analysis. This monitor uses filters to collect major components of particulate matter less than 2.5 micrometers (PM2.5). These major components are sulfate, nitrate, organics, elemental carbon, and soil. 

Using the data gathered from the monitors, ARAQMD calculates and publishes the Air Quality Index.