Air Pollution called particulate matter includes dust, dirt, soot, smoke and liquid droplets directly emitted into the air by sources such as factories, power plants, cars, construction activities, fires, and natural windblown dust. Particles formed in the atmosphere by condensation or the transformation of emitted gases such as sulfur dioxide and volatile organic compounds are also considered particulate matter. Particles less than 2.5µ in diameter are formed primarily by combustion or secondary chemical reactions in the atmosphere whereas particles greater than 2.5µ are formed primarily by mechanical processes (construction, demolition, wind erosion). Since particles originate from a variety of mobile and stationary sources, their chemical and physical compositions vary widely depending on location and time of year.

The Air Program's goal is to better understand the concentrations and pattern of particulate matter. This data will be used for comparison to the national standards as well as provide useful data for reporting short-term concentrations for understanding diurnal and episodic behavior of fine particles. It can also be utilized by health scientists investigating exposure patterns, (i.e. asthma studies).

Samples are collected continuously with two monitors known as the TEOM, Tapered Element Oscillating Microbalance. The monitor is a true "gravimetric" instrument that draws ambient air through a filter at a constant flow rate, continuously weighing the filter and calculating near real-time (10 minute) mass concentrations.

The first unit collects particulate matter of 10 microns or less, and being equipped with the optional Automatic Cartridge Collection Unit (ACCU) can also collect particles of 2.5 microns and less. The second unit collects only 2.5 microns or less.