Ozone Monitoring

Overview

Great Basin National Park, Nevada

The NPS Air Resources Division operates a network of air quality monitoring stations (sometimes refered to as the Gaseous Pollutant Monitoring Network - GPMN) that measures primarily meteorological parameters and ozone. Sulfur dioxide is measured using continuous analyzers or with filter samplers in a subset of the network. The 1991 NPS Monitoring Strategy contains the monitoring plan that includes long-term "trends sites" and 3-5 year "baseline sites." Many stations are now operated jointly with the EPA CASTNet.

The gaseous pollutant monitoring program historically concentrated on determining the levels of two gaseous air pollutants, ozone and sulfur dioxide, which are most toxic to native vegetative species found in NPS units at levels at or below the National Ambient Air Quality Standards NAAQS). Other gaseous pollutants (e.g., other photochemical oxidants, nitrogen compounds, and toxic organic compounds) are also of interest to the NPS because they relate to physiological, morphological, or historical injury to park biological resources, or to global climate change. Currently, only selected, limited studies measure other gaseous pollutants within the National Park System. Ozone and sulfur dioxide monitoring in national parks has been ongoing since the early 1980s using EPA reference or equivalent methods. This allows for the direct comparison of NPS data with data collected by state and local air pollution control agencies and EPA.

Many of the documents on this page are in PDF format. PDF files require the Adobe Acrobat reader to view and print. Download a FREE copy of the reader here.

Monitoring network overview This document lists the NPS monitoring objectives, the basics of the monitoring strategy, and information about the operation of the network. (500 Kb PDF file) How the NPS ozone monitoring fits into US air quality monitoring is explained in a brochure. Related NPS ozone monitoring includes special studies programs using passive samplers, portable O3 monitors, and enhanced multi-pollutant analyzers. The US EPA has set an ozone national standand (NAAQS) of 85 ppb over an 8-hour period for human health and for natural resources. The standard is a calculated value over 3 years using the 4th highest annual ozone of the daily maximum 8-hour averages. See EPA for the full details.

NPS Monitoring Objectives Identify air pollutants which may injure or damage park natural resources, measure these pollutants, and correlate observed effects on resources to ambient levels of pollutants Establish baseline visibility conditions, deposition, and air pollutant concentrations in national parks Identify and assess trends in air quality Determine compliance with National Ambient Air Quality Standards Provide data for the development and revision of national and regional air pollution control policies that are protective of park resources Provide data for atmospheric model development and evaluation Determine the relative importance of various atmospheric constituents to visibility impairment Determine the sensitivity of individual areas or views to variations in visual air quality

Locations

Most of the ozone monitoring locations are in mandatory Class I parks. A few stations are operated by State agencies, but within the parks.

• List of active sites and the air quality parameters measured. A quick table to identify the active monitoring sites and what parameters are being measured.
• Sites and air quality parameters measured since 1987 - the Monitoring History database provides detailed information on how long and what has been measured.

Procedures

Air quality instrumentation are calibrated and serviced in a laboratory prior to deployment for special studies or routine monitoring

The standard NPS monitoring station measures ozone using a UV-absorption analyzer, a transfer standard, a weather station including wind speed, wind direction, temperature at two heights, solar radiation, relative humidity, and a wetness sensor, a stacked filter-pack designed to measure sulfate, sulfur dioxide, nitrate, ammonium, and nitric acid, and at some sites a sulfur dioxide analyzer. Operators for the stations are provided by the parks and a contractor maintains and calibrates the network equipment. Data is transmitted nightly over the phone to a contractor who validates and archives the data. Hourly data files are transfered to the EPA Air Quality Systems database and made available on the web.

• Quality Assurance Plan (.8 mb PDF) for the NPS gaseous pollutant monitoring network.
• Quality Management Plan (.3 mb PDF) for the NPS gaseous pollutant monitoring network.
• The on-line Standard Operating Procedures for site operators of the monitoring stations. These are the procedures and forms used at the air quality stations in the NPS monitoring network.
  
• Ozone Monitoring Protocol for the Inventory and Monitoring program (580 kb PDF)
  
  PDF files require the Adobe Acrobat reader to view and print. Download a FREE copy of the reader here.

Data

Results

An Annual Data Summary Report is issued for each park with an ozone monitoring station in the fall of the year following data collection. These reports include the final data, statistical summaries, ranking tables, and graphical summaries. Below are ozone summary tables and report products.

• Monthly Summary Report of Weather, Ozone and SO2 Data for all parks (May, 2007)
• Annual Data Summary Reports
• Current year summary tables of 2007 high ozone concentrations and exceedances of the National Ambient Air Quality Standard (NAAQS) based on screened preliminary data. Preliminary data are used to get a quick look at the high 8-hour ozone averages that exceed 85 ppb.
• Historical Ozone Concentrations in National Parks, 1983 - 2006
• Historical Ozone Exceedances in National Parks, 1982 - 2006
• US maps 1994-2002 of annual SUM06 ozone statistic (ppm-hrs) as proportional circles for all NPS sites monitored.

Additional Results

Real-time air quality data displays have been placed in Great Smoky Mountains, Big Bend, and Grand Canyon National Parks, and Craters of the Moon National Monument. The real-time data and pictures of the visitor display are available on the Internet. Information on air quality at Great Smoky Mountains has been summarized in a folio (pdf format). See WebCams for other parks.

AirNow - Map of Todays' Ozone. Daily contour plots of ozone concentrations are available from EPA during the ozone season and include input from National Park Service monitoring stations. These maps are handy for understanding regional distributions and movements of ozone.

Ozone trends are an important component of the monitoring object. Summary data from the hard copy report "Quick Look Annual Summary Statistics Report" and the "Annual Data Summary Report" can now be viewed with the web-based interactive trend plotter. The present air quality can be assessed in relation to the National Ambient Air Quality Standard and the newly proposed changes to the standard. Trends can then be considered to determine an overall condition.

Contacts