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

Please see www.epa.gov/airtrends for the latest information on Air Quality Trends.

Principal Pollutants:  
CO Carbon Monoxide
Pb Lead
NO2, NOx Nitrogen Dioxide, Nitrogen Oxides
O3 Ozone
PM-10 Particulate Matter (diameter of 10 micrometers or less)
SO2, SOx Sulfur Dioxide, Sulfur Oxides
CFCs Chlorofluorocarbons
DU Dobson Unit(s)
EPA Environmental Protection Agency
FCCC Framework Convention on Climate Change
HFCs Hydrofluorocarbons
IPCC Intergovernmental Panel on Climate Change
NAAQS National Ambient Air Quality Standard
PAMS Photochemical Assessment Monitoring Stations
NTI National Toxics Inventory
PFCs Perfluorinated Carbons
TRI Toxic Release Inventory
TSP Total Suspended Particulates
VOC Volatile Organic Compounds

This document is provided for historical purposes only. The most recent version can be found at AIRTrends

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