NPS: Nature & Science » Networks: National Capital Region Network

National Capital Region Network - Monitoring Ozone

Background

Ground-level ozone is regulated under the Clean Air Act, the comprehensive federal law that regulates air emissions in the United States. Information about the Clean Air Act can be found here. Among other things, the Clean Air Act requires the U.S. EPA to set standards for “criteria pollutants” – six commonly occurring air pollutants, one of which is ground-level ozone. These standards, known as the National Ambient Air Quality Standards (NAAQS), define the national targets for acceptable concentrations of each of the criteria pollutants.

Ozone is measured by the Clean Air Status and Trends Network (CASTNet), Maryland Department of Natural Resources, and the City of the District of Columbia. All these agencies use standard reference methods for the measurement of ozone, as designed by the EPA. A web-based clearinghouse for qualitative ozone data and forecasts can be found on the EPA AIRnow website. Trends for the Midatlantic region and for specific counties in the NCRN are also available at the EPA Air Trends website. The I&M program will rely on data from this site for qualitative estimates of ozone trends, and obtain data directly from these sites via download.

Objectives

Assess seasonal and annual status and treds of ozone concentrations in NCRN parks using metrics that are indicative of human health (e.g. fourth-highest daily maximum 8-hour concentration) and plant response ( W126).

Measures

The NCRN will rely on data from the reports and graphics generated by ARD to report on status and trends in ozone concentration in the network parks. When appropriate, the NCRN will supplement information obtained from ARD with other data summaries and interpretations.

Status

Ozone monitoring uses standard reference methods for the measurement of ozone and has strict quality assurance and control requirements for collecting and reporting data. Data are entered into a database maintained by the EPA. Monitoring specialists at the NPS Air Resources Division (ARD) will download the relevant ozone data from the database and summarize the data in ways that are useful to parks and I&M Networks.