Ambient Air Monitoring Station The Virginia Department of Environmental Quality (DEQ) installed an ambient air monitoring station at Albemarle High School in early 2008. The station measures particulate matter 2.5 micrometers or smaller in size (PM2.5) and ozone. The PM2.5 and ozone data collected at the station is available on http://www.airnow.gov/ and http://www.deq.virginia.gov/airquality/ . Meteorological data will also be collected at the station. Contact Lindsay Check at Building Services if you would like additional information ( lcheck@k12albemarle.org or 975-9340).
Summary of Monitored Pollutants Particulate Matter less than 2.5 microns (PM2.5) Particulate matter is the term used for a mixture of solid particles and liquid droplets found in the air. Coarse particles (larger than 2.5 micrometers) come from a variety of sources including windblown dust and grinding operations. Fine particles (less than 2.5 micrometers) often come from fuel combustion, power plants, and diesel buses and trucks. These particles can pass the terminal and respiratory bronchiole in the lungs and lodge in the alveoli. In addition to negative health effects, PM2.5 can impair visibility, have an effect on climate, and contribute to acidic dry deposition. PM2.5 can impact locally or travel across oceans to impact other countries. These fine particles are so small that several thousand of them could fit on the period at the end of this sentence. They are of health concern because they easily reach the deepest recesses of the lungs.
The PM2.5 TEOM (Tapered Element Oscillating Microbalance) is a continuous sampler. Air is drawn through the roof inlet, and down to the sensor unit in the shelter. Particulate in the air stream is captured on a small filter situated on a device akin to a tuning fork. As particulate collects on the filter, it changes the measured oscillation frequency and this signal is converted into a measurement of total mass loading. Data is recorded as one hour averages.
Ozone (O3) Ozone is the prime ingredient of smog in our cities and other areas of the country. Though it occurs naturally in the stratosphere to provide a protective layer high above the earth, at ground-level it is the prime ingredient of smog. Ozone is formed by a complex series of reactions among nitrogen oxides and certain organic compounds under the influence of solar ultraviolet radiation (sunlight). Ozone shows a very strong diurnal (daily) and seasonal (April to October) cyclical character. It injures vegetation, has adverse effects on materials (rubber and fabrics) and is a pulmonary irritant that affects the respiratory mucous membranes, lung tissues and respiratory functions. Ozone is measured by ultraviolet absorption photometry. Air is drawn continuously through a sample cell where narrow band ultraviolet light (254nm wavelength) passes through it. The proportion of light absorbed by ozone molecules in the air is converted into an electrical signal and recorded. Air Monitoring Station Materials Department of Environmental Quality - Introduction to Station Data Presentation
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Friday, November 20, 2009
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