Photochemical Assessment Monitoring Stations

Note: EPA no longer updates this information, but it may be useful as a reference or resource.

Summary of Actual Sampling Frequencies

Revised September 11, 1998

Definitions:
AIRS -	Aerometric Information Retrieval System - Site ID contains 9 digits; "xx-xxx-xxxx" indicates that a number has not yet been assigned.
Cont. -	Continuous measurement
Ep -	Ozone episode day; also referred to as Hi Day
Hi Day -	Day with high ozone concentrations, measured or forecast
NO_y -	Total Reactive Oxides of Nitrogen
Prev -	Previous Day
TNMOC -	Total Non-Methane Organic Compounds
Unk -	Unknown
VOC -	Volatile Organic Compound(s)
YR -	Year Round

Frequency Shorthand:

Actual sampling frequency is given as (# of samples)-(sample time in hours)-(how often in days), for example:

"24-1-1" means 24, 1-hour samples everyday

"8-3-3" means 8, 3-hour samples every third day

"1-24-6YR" means 1, 24-hour sample every sixth day year round

Site Numbers:

Site #1 - Characterizes upwind background and transported ozone/precursor concentrations entering the area and identifies those areas which are subjected to pollutant transport. The #1 Sites are located in the predominant morning upwind direction from the local area of maximum emissions and at a distance sufficient to obtain urban scale measurements.

Site #2 - Monitors the magnitude and type of emissions in the zone where maximum precursor emissions representative of the affected area are expected to impact. The #2 Sites are located immediately downwind (using the same morning wind direction for locating Site #1) of the area of maximum emissions and are typically placed near the downwind boundary of the central business district to obtain neighborhood scale measurements representative of the area. Additionally, a second #2 Site, called the #2A Site, in the second-most predominant morning wind direction is required for larger areas.

Site #3 - Monitors the maximum ozone concentrations which occur downwind from the area of maximum emissions. Locations are chosen so that urban scale measurements are obtained. Typically, sites are located in the predominant afternoon downwind direction from the local area of maximum precursor emissions at a distance sufficient to obtain urban scale measurements.

Site #4 - Quantifies the extreme downwind pollutant concentrations which exit the area and identifies those areas which are potentially contributing to transport into other areas. The #4 Sites are located in the predominant afternoon downwind direction from the local area of maximum precursor emissions at a distance sufficient to obtain urban scale measurements.

Sites which are identified with two numbers, e.g., 3/1, indicates that the site serves two purposes. In this case, the site is a downwind #3 Site for one area and an upwind site or #1 Site for a nearby area.

Atlanta, Georgia

Parameter	Name	Site	AIRS	1994	1995	1996	1997	1998
VOC	Yorkville	1*	13-223-0003	---	---	24-1-1 1-24-6YR	24-1-1 1-24-6YR	24-1-1 1-24-6YR
	South DeKalb	2*	13-089-0002	---	24-1-1 1-24-6 YR	24-1-1 1-24-6 YR	24-1-1 1-24-6YR	24-1-1 1-24-6YR
	Tucker	2A*	13-089-3001	---	24-1-1 1-24-6YR	24-1-1 1-24-6 YR	24-1-1 1-24-6 YR	24-1-1 1-24-6 YR
	Conyers	3	13-247-0001	---	24-1-1 1-24-6YR	24-1-1 1-24-6YR	24-1-1 1-24-6YR	24-1-1 1-24-6YR
	Monticello	4	xx-xxx-xxxx	---	---	---	---	Deferred until 1999
Carbonyls	South DeKalb	2	13-089-0002	---	---	24-1-1 1-24-6 YR	24-1-1 1-24-6 YR	4-3-3 1-24-6 YR
Carbonyls	Tucker	2A	13-089-3001	---	---	24-1-1 1-24-6 YR	24-1-1 1-24-6 YR	4-3-3 1-24-6 YR