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Ambient Air Monitoring

The Air Quality Center's surface air monitoring (SAM) site is located approximately two miles southwest of downtown Athens, Ohio. At an elevation of 950 feet asl, the site location is the highest visible point in the region, higher than any point south to the Ohio River and southwest to Cincinnati. It is an excellent site from which to capture the transport of pollutants into and out of the valley. The monitoring site has doubled in size since its initiation in March 2004, and now features 26 major instruments.

Continuous mercury monitoring: Total Gaseous Mercury, Speciated Mercury, and Particulate Mercury.

The Tekran 2537A, 1130, and 1135 components detect elemental mercury (Hg0) on five minute averages. Reactive gaseous mercury (RGM) and particulate mercury (Hgp) are recorded on one-hour increments.

Mercury Wet Deposition

Measurement of the concentration of mercury in precipitation events (both rain and snow) is accomplished with the use of an AeroChem Metrics precipitation collector. The site is a member of the U.S. Mercury Deposition Network. Weekly sample collections are shipped to Frontier Geosciences, Inc., in Seattle, Washington, for analysis.

Continuous Gases

NOx analyzer SO2, NO, NO2, NOx, NOy, O3, Carbon and Sulfate concentrations are continuously recorded on a continuous basis using the following analyzers:

  • SO2: Teledyne model 100A fluorescent analyzer.
  • NOx: Teledyne model 200A chemiluminescent-based analyzer, pictured above.
  • NOy and CO-Ultra analyzes O3: Teledyne model 400A ultraviolet analyzer.
  • CO (ppm): Teledyne model 300 infrared analyzer.
  • CO-Ultra (ppb): Teledyne model 300EU Trace Level CO analyzer, pictured to the right.
  • Elemental and Organic Carbon: Rupprecht and Patashnick series 5400 ambient carbon monitor.
  • Sulfate: Rupprecht and Patashnick series 8400S ambient SO42- monitor.
  • NOy: Teledyne model 501Y with exterior NOy converter. NOy monitor also records NO-ultra and NO2-ultra (ppb range), pictured to the right.

The following instrument components are used to record continuous data and perform instrument quality control protocol:

  • ESC Data LoggerESC Model 8816 Data Logger, pictured to the right.
  • Daily instrument span checks and manual calibration is performed using an API Model 700 Dynamic Dilution Calibrator.
  • Daily instrument zero checks and manual zero calibrations is performed using an API Model 701 Zero Air Generator.

All API instruments are included in an API model 900 ambient monitoring trailer. R&P sulfate and Carbon instruments are housed in a separate shed. All continuous gas and meteorological data streams are sent to the data logger for continuous uploading to a secure server.

Tapered Element Oscillating Microbalance (TEOM) with Sample Equilibration System (SES)

This instrument has operated continuously since January 2003 with little interruption. It continuously measures the PM2.5 concentration. Particulate matter is size-selected using a PM inlet and sharp cut cyclone. It flows through two naphion dryers and an SES humidity reduction unit to reduce the moisture in the sample lines. Particulate collects on a small transducer filter which triggers a small tapered element to oscillate in proportion to the amount of particulate collected. Filters are replaced approximately every three weeks or when full. This sampler has agreed with the PM2.5 FRM sampler very closely. The FRM is described below.

Tapered Element Oscillating Microbalance (TEOM) with Filter Dynamics Measurement System (FDMS)

The FDMS system has been added to two additional TEOM units to conduct an instrument inter-comparison study. A total of 3 TEOMs will be compared with the Federal Reference Method (below).

Federal Reference Method (FRM) PM2.5 Sampler

The FRM particulate matter sampler operates on a 1 in 3 day schedule, for a programmed period of 24 hours. Air is drawn in through the PM inlet and sharp cut cyclone, which separates the particles of size 2.5 µm or smaller. These particles collect on a quartz filter within the sampling chamber. This filter is removed and analyzed by weight by Consol Energy, R & D.

PM2.5 Chemical Speciation Sampler

The Chemical speciation sampler operates concurrently with the FRM sampler, shown above. Gravimetric mass, trace metals, and water-soluble ions are analyzed by Consol Energy, R & D. Speciation data can also be substituted in place of the FRM if the instrument is not in operation.

Manual denuder method

This manual sampler operates on a 1 in 6 day schedule, in conjunction with the particulate matter samplers above. Ammonia and PM2.5 speciations are analyzed by the Illinois State Water Survey.

Meterological Parameters

Ambient air temperature (degrees C), barometric pressure (inches Hg), solar radiation (watt/m2), relative humidity (%), wind speed (mph) and wind direction (compass degrees) are continuously acquired in 15 min. and 1 hour averages from a 10 meter meteorological tower (left). Wind speed and wind direction are also measured atop a 400 foot aerial communications tower (right) located just offsite. The data is manually downloaded every three days and used for back trajectory/source apportionment purposes.


The Manual Belfort Rain Gauge (left) records precipitation via the use of a weighted bucket. The precipitation event beginning and ending times, along with the amount of precipitation received are recorded on a strip chart within the instrument. The tipping bucket rain gauge (right) logs every rain event to the 0.01 inch level. Tipping bucket data is acquired on 15-minute and 1-hour averages. 24-hour total precipitation data is also available.


The Nephelometer is a new addition to the site. It continuously acquires visibility data (ambient Beta scattering) on 5 minute intervals.