Our agency measures the ambient air in and around Marion County for pollutants which have National Ambient Air Quality Standards (NAAQS). These pollutants are referred to as the criteria pollutants and include carbon monoxide (CO), ozone (O3), sulfur dioxide (SO2), nitrogen dioxide (NO2), particulate matter 10 micron (PM10), particulate matter 2.5 micron (Fine Particles), and lead (Pb). The air quality standards are set at levels to protect the public health. Monitoring is conducted to assure compliance of those standards. The gaseous pollutants (CO, O3, SO2) are measured 24 hours a day, 7 days a week by our staff. The particulate type pollutants (Fine Particles, PM10, Pb) are collected over a 24 hour period and measured once every day (Fine Particles) to every 6th day (PM10 and Pb). Each year the agency collects nearly 130,000 total air measurements.