Air quality monitoring at DEQ
The Oregon DEQ is a regulatory agency whose job is to protect and enhance the
quality of Oregon's environment. In support of that job, the Air Quality
Monitoring Section of the DEQ’s Laboratory Division is responsible for providing
accurate scientific data concerning the State of Oregon’s air quality to ensure
that the state meets the National Ambient Air Quality Standards as
required by the Federal Clean Air Act.
DEQ measures air pollutant levels by operating a network of monitoring and
sampling equipment at sites throughout the State of Oregon. These sites are
operated and maintained by DEQ air monitoring technicians with the goal of
collecting complete and accurate air quality data. The equipment at an air
monitoring station can vary from a complex array of continuous air monitors that
operate 24 hours a day year-round to a single sampler with a filter that
captures particulates once a week. Much of the data collected from the air
monitoring network is submitted to the Environmental Protection Agency
data base for use in determining air pollution trends and air quality compliance
of the NAAQS standards.
Each year DEQ updates our Air Quality Monitoring Network Plan and submits it to the public for comment. We then submit it to EPA for approval. The plan is up for public comment from June 1 for 30 days each year. It is submitted to EPA on July 1.
DEQ monitors for Federal Clean Air Act pollutants including carbon monoxide
(CO), nitrogen dioxide (NO2), ozone (O3), total suspended particulate (TSP), fine particulate (PM10 and PM2.5)*, and lead (Pb). Other pollutants or
compounds are measured as part of air toxics or particulate speciation
The department also provides monitoring and technical assistance in support
of the following AQ monitoring projects and studies:
- Field Burning Network - grass field burning in the Willamette Valley in
cooperation with the Oregon Department of Agriculture. Agricultural Burning in
the Grande Ronde Valley.
- Visibility Network - located in federally designated wilderness areas and national parks.
- Forest Health Network - areas in southwest and northeast Oregon impacted by smoke from
federal lands. Operated in cooperation with the US Forest Service and the BLM.
- Local wood stove advisory and pollution prevention programs
DEQ has been funded to add another 30 PM2.5 AQI sites around the state. We are currently working to develop the new low cost sensor technology that will enable us to add these sites. The decisions on where the sites will go is outlined in the document below.
Location Selection and Rational for 30 New Monitoring Sites
An area of increasing interest is the monitoring of Air Toxics or HAPs
(Hazardous Air Pollutants). DEQ has permanent air toxic trend sites and rotating air toxics assessment sites. DEQ prioritizes where air toxics monitors are placed using several criteria. These are discussed in the following three documents:
*Fine particulate air pollution consists of solid particles or liquid
droplets that are less than 10 microns in diameter (PM10) or less than 2.5
microns in diameter (PM2.5). Particles in these size ranges are of great concern
because they can be inhaled deeply into the lungs where they can remain for
years. The health effects of particulate matter vary with the size,
concentration, and chemical composition of the particles.
Typical Oregon air monitoring station
Explanation of sensors and samplers below. Interior. Instruments: CO monitor, datalogger, chart
recorders, meteorological translator and RGVAV (reference gas vacuum adjust valve).
1. These meteorological sensors record wind speed and wind direction data. This data is collected electronically using strip chart recorders and a datalogger located inside the air monitoring station. Most of the samplers and monitors located at this station give continuous information that is available electronically through the agency’s data acquisition system.
2. and 3. These are upper and lower temperature sensors. The difference between the upper and lower temperature readings helps determine the stability of the air near the ground. A large temperature difference indicates an air inversion in the area. An air inversion can trap pollutants near the ground that can be harmful to public health. Barometric pressure is also recorded at this station. Meteorology is important in determining weather conditions in an area. Weather can influence pollution levels.nd2. and 3. These are upper and lower temperature sensors. The difference between the upper and lower temperature readings helps determine the stability of the air near the ground. A large temperature difference indicates an air inversion in the area. An air inversion can trap pollutants near the ground that can be harmful to public health. Barometric pressure is also recorded at this station. Meteorology is important in determining weather conditions in an area. Weather can influence pollution levels.
4. A probe is connected to a fine particulate (visibility) monitor called a nephelometer located inside the air monitoring station. A pump pulls ambient air through the probe and into the nephelometer which can detect particulates like smoke or dust. During the winter months wood stove smoke can contribute significantly to the amount of particulate in the air. In the summer, barrel burning, open burning, slash burning, forest fires, and field burning contribute to the amount of particulate that impacts an area.
5. These are PM10 and PM2.5 fine particulate samplers. Air is drawn through inlets located on the top of the samplers onto filters. The inlets are designed to limit the size of the particulate reaching the filters. The filters go to the DEQ Laboratory where they are weighed for mass, and/or analyzed for other compounds, including carbon and metals. Air Monitoring Technician records sample information, exchanges filters, and reprograms the sampler for the next sample date. All of the instruments are reviewed, operated, maintained and calibrated by DEQ staff.