Types of Air Monitors

OZONE - Monitored continuously. A sample of the ambient air is compared to a sample that has been scrubbed clean of ozone. Measurement is accomplished by the use of an ultraviolet light source.

PM10 (HiVol) - Monitored on a 6 day schedule. Its name is derived from the fact that it draws large volumes of air through the filter upon which the particulate matter (PM) is retained. Originally used for the sampling of total suspended particulate (TSP), a modification of this technology was required to accommodate monitoring of PM10. A specially designed sampling inlet was added that removes particles >10 µm so that particles in the PM10 size range are selectively retained on the filter. This type of sampler is therefore called a size selective inlet (SSI) hi-vol sampler. Data collected every 6 days.

PM 2.5 - Monitored on a 6 day schedule. Monitor is equipment that intakes ambient air (i.e., the air we are exposed to) at a known rate for a period of 24 hours and captures particulate matter (PM) less than 2.5 microns in diameter on a filter. The filter is sent to a laboratory where it is weighed. The ambient concentration of particulate matter less than 2.5 microns in diameter can then be determined in micrograms per cubic meter.

PM 2.5 BAM - Monitored continuously. At the beginning of the sampling period, beta ray transmission is measured across a clean section of filter tape. This section of filter tape is then mechanically advanced to the sampling inlet. Particulate matter is then drawn into the sample inlet and deposited on the filter paper. At the completion of the sampling period, the filter tape is returned to its original location and beta ray transmission is re-measured. The difference between the two measurements is used to determine the particulate concentration.

* The data from the  Beta Attenuated Monitors (BAMS) are not used as part of the State and Local Air Monitor Station (SLAMS).

** Special purpose - the real time particulate matter data is for public information reporting and forecasting only. Per state and federal regulations, it is not used for attainment determination purposes.