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Last Updated: Oct 16th, 2008 - 13:33:17 |
Glowing yellow signs above I-25 warned motorists the night of July 16 looming ground-level ozone emissions. The message pleaded with drivers to limit their time on the road Tuesday.
Ozone levels in the metropolitan area are as high as ever, and with only a couple of months before Denver's extension of federal noncompliance runs out, Environmental Protection Agency violations may be the least of the city's worries: ozone is a lung irritant, detrimental to local ecology and byproducts of its reaction with other chemicals create a suspected carcinogen that isn't monitored by the city.
"Its basically a little sunburn on your lungs," said Gregg Thomas, environmental assessment and policy supervisor for Denver's Department of Environmental Health, of ozone's impact on human health. While all metro-area residents have no choice but to inhale the noxious fumes, some are more at risk than others.
"Ozone typically hits people who have compromised cardiovascular systems," said Celia Vanderloop, director of Denver's Department of Environmental Quality. Most at risk are children, the elderly and people with asthma.
"Repeated ozone impacts on the developing lungs of children may lead to reduced lung function as adults," states a webpage on Airnow.gov.
The federal government could soon be regulating Denver's air; the metro-area has surpassed the EPA's ozone-emission standards twice this year. Under U.S. supervision, filling stations may be required to carry cleaner-burning high-octane gasoline and the city could lose federal transportation funding.
"The Rocky Flats monitor has violated the standard three times this year," Vanderloop said. "We would potentially be looking at putting more controls on oil and gas sources" if Denver becomes federally regulated.
"There's also the potential that ... Ft. Collins and Greeley could be looking at something," she said.
Climate, meteorological effects, a dense population and a usual hot Denver summer have contributed to high ozone levels, Vanderloop said, adding that Denver's stagnant air traps ozone, nitrogen oxides, or NOx, and volatile organic compounds, or VOCs, rather than allowing breeze to blow the pollutants hundreds of miles away.
Ozone reacts with NOx to form peroxy acyl nitrate, or PAN, an eye and lung irritant suspected to play a role in cancer and heart disease. PANs have also been called detrimental to forest in the Los Angeles area.
Despite the effects ozone and PANs have on local ecology, little if any federal monitoring is done to examine their effects.
"That's something we don't really monitor for," Thomas said of PAN levels in Denver's troposphere. The troposphere is the lower portion of the atmosphere that contains the air we breathe.
In 1997 the EPA revised existing standards to tighten acceptable ozone emission levels. Major U.S. areas across the country were evaluated in April 2004 for compliance, and Denver was found to have unacceptable levels of ozone. According to the EPA, the city entered into an early action compact to lower ozone emissions to acceptable levels by Dec. 31, 2007.
"The state will submit a report at the end of the summer. There are a lot of eyes on this data, so we'll know," Thomas said. "We're either going to violate or we're not."
Even if Denver makes it through the summer and is still within presently acceptable levels, it may have a hard time meeting new standards that will be finalized in spring 2008.
"We have some pretty significant challenges ahead," Thomas said. "A lot of the monitors in the Front Range, at least for the next couple years, will probably be above (the new EPA) limits."
What can residents do to decrease their contributions to ground-level ozone?
"Don't fill up your gas tank until later in the evening," Vanderloop said, noting that people should also limit driving if possible. "Don't mow your lawn during the middle of the day. ... Try to delay the release of those emissions until its not quite as hot."
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