AirData

Many AirData reports and maps have the types of selection criteria described below.

Geographic Area

The name of the geographic area you selected previously is displayed here. To choose a different area, click on the "(Change)" link beside the geographic area heading.

Pollutant

The pollutant monitored or emitted. A report includes only monitors that measure the selected pollutant, or sources that emit it. You may select multiple pollutants for a report - all pollutants, unless a report specifies fewer selections.

An AirData report includes pollutants from one of the following groups.

Monitors - Criteria Air Pollutants

• CO - carbon monoxide
• NO2 - nitrogen dioxide
• SO2 - sulfur dioxide
• O3 - ozone
• PM2.5 - particulate matter with diameter <2.5 micrometers
• PM10 - particulate matter with diameter <10 micrometers
• Pb - lead

Monitors - Hazardous Air Pollutants

Approximately 200 hazardous air pollutants may be monitored to determine their ambient concentrations in air. They include individual organic compounds (e.g., benzene), classes of organic compounds (e.g., polychorinated biphenyls), and inorganic compounds of certain metals (e.g., arsenic).

Sources - Criteria Air Pollutants and Precursors

• CO - carbon monoxide
• NOx - nitrogen oxides
• SO2 - sulfur dioxide
• VOC - volatile organic compounds
• PM2.5 - particulate matter with diameter <2.5 micrometers
• PM10 - particulate matter with diameter <10 micrometers
• NH3 - ammonia

Sources - Hazardous Air Pollutants

A list of the 188 hazardous air pollutants is available at EPA's Air Toxics web site. The list includes individual organic compounds (e.g., benzene), classes of organic compounds (e.g. , glycol ethers), and metals and their compounds (e.g., arsenic). For details, see the complete list of hazardous air pollutants for which EPA collects emissions data.

Year of Data

The calendar year in which monitoring sites measured air pollutant concentrations or sources released air pollutants.

For most AirData reports and maps, you may select multiple years. Data relevant to any of those years are included in the report or map. For example, if you selected years 2000 and 2001 for a report of air monitoring data, it would include monitoring sites that reported data in either of those years (or both).

Reports of hazardous air pollutant emissions do not have a year selection because data are available for only one year, 1996. When data for additional years become available, year selection will be added to these AirData reports.

Exceptional Data

AirData reports of air monitoring data have an option to include "exceptional" data, which refers to high pollution levels caused by an exceptional event such as a wildfire. EPA regulations allow these data, if properly documented and approved, to be excluded from the determination whether a community met Federal air quality standards. About 6% of monitoring sites report exceptional data in a given year, and EPA approves (excuses) about one-third of the exceptional data.

By default, AirData reports and maps omit approved exceptional data. To include all monitoring data in a report, select the exceptional data option.

Lines per Page

The number of rows displayed on each page of an AirData report. Dividing the report into pages allows you to view it in sections small enough for your browser to handle easily. Use caution in selecting the two largest page size options; they may adversely affect browser performance.

Report Columns

You may omit some data columns from AirData reports. Be aware that including or excluding columns may change the way a report summarizes data. The help page for each report explains how column inclusion or exclusion affects report content.