WASHINGTON, DC, October 3, 2007 (ENS) - Ground-level ozone forecasts, for years a key predictor of air quality in major U.S. cities, are now posted and mapped online on an hourly basis throughout the lower 48 United States. Ground-level ozone is a main ingredient of urban smog, that brown cloud hanging over the skylines of urban areas.

"Poor air quality is a silent killer, responsible for tens of thousands of premature deaths each year in the continental United States," said Jack Hayes, Ph.D., director of the National Weather Service, an agency of the National Oceanic and Atmospheric Administration, NOAA.

"Weather and air quality are strongly linked. Temperature and lack of wind can create and trap harmful ozone where we work and play," said Hayes. "Our ozone forecasts will enable city and state air quality managers to look ahead, see trouble brewing, and issue next-day alerts for poor air quality."

The National Weather Service, in partnership with the U.S. Environmental Protection Agency, EPA, has extended its ozone forecast to 11 western states and expanded the service in six other states, ensuring that the most populous cities throughout the country will have access to the ozone forecasts on a daily basis.

Hour-by-hour ozone forecasts, through midnight of the following day, are available online, providing information for the onset, severity and duration of poor air quality for more than 290 million people from coast to coast.

States added to the expanded ozone forecast area are Arizona, California, Colorado, Idaho, Montana, Nevada, New Mexico, Oregon, Utah, Washington, and Wyoming, and the western portions of Kansas, Nebraska, North Dakota, Oklahoma, South Dakota and Texas.

"NOAA’s expanded forecasting guidance gives state and local agencies another important tool for bringing air quality information directly to citizens,” said Bob Meyers, the EPA’s principal deputy assistant administrator for air and radiation. "Air quality forecasts help Americans across the country reduce their exposure to pollution and lead healthier lives."

The primary constituent of smog, ozone is a gas that is not usually emitted directly into the air. At ground-level it is created by a chemical reaction between oxides of nitrogen, NOx, and volatile organic compounds, VOCs, in the presence of sunlight.

Motor vehicle exhaust and industrial emissions, gasoline vapors, and chemical solvents emit NOx and VOCs that form ground-level ozone.

Ozone has the same chemical structure -three oxygen atoms - whether it occurs in the stratosphere six to 30 miles above the Earth or at ground-level. It can be good or bad, depending on its location in the atmosphere.

In the Earth's lower atmosphere, ground-level ozone is considered bad. In the stratosphere, it is considered good because it shields the Earth from the harmful ultraviolet rays of the Sun.

The program to forecast ground-level ozone was established in 2004 in several northeastern states. It has been built by a team of NOAA and EPA scientists who develop, test and implement improvements in the science of air quality forecasting for real-time predictions.

National Weather Service’s weather forecast models drive simulations of atmospheric chemical conditions using pollutant emissions and monitoring data provided by the EPA.

Twice daily, supercomputers operated by NOAA’s National Centers for Environmental Prediction produce ground-level ozone forecasts, which are available on National Weather Service and EPA data servers.

To access the ground-level ozone forecasts, click here.

Copyright Environment News Service (ENS) 2007. All rights reserved.