With summer comes an increase in ground-level ozone, and Clark County has issued an ozone advisory through the end of September.
Exposure to ozone also can induce coughing, wheezing and shortness of breath, even in healthy people. When ozone levels are elevated, officials advise everyone to limit strenuous outdoor activity.
"People who have asthma, lung disease or heart ailments or those who are very active outdoors are at risk," said Dennis Ransel, planning manager for Clark County’s department of air quality. "If you’re outdoors jogging and deep breathing, that can irritate your lungs and, over time, cause you some health issues."
In 2008, the U.S. Environmental Protection Agency adopted a stringent standard for ozone of 75 parts per billion. Air-quality officials say the county is close to exceeding the new standard. If the county fails to meet the 75 ppb standard, the community will need to implement new measures to reduce emissions, officials said. One part per billion is equivalent to roughly one drop of water in an Olympic-size swimming pool.
"We meet the new health-based standard for ozone but just barely," said Lewis Wallenmeyer, director of the county’s department of air quality. "We need to remain vigilant in our efforts to reduce ozone pollution."
Ozone is a key ingredient of urban smog during the hottest months of the year. Ground-level ozone can build up during the afternoon hours due to a combination of several factors, including strong sunlight, hot temperatures and pollutants from automobiles and other sources, such as wildfires.
In 1985, the valley logged a record 41 unhealthy air days due to carbon monoxide. In January 1993, the area was designated as serious for non attainment for particulate matter or PM-10 , a form of dust pollution.
Local air quality has improved significantly since July 2001, when the Clark County Commission was designated as the air pollution control agency for Southern Nevada. The county now meets health standards for carbon monoxide and PM-10.
Clark County Commission Chairwoman Susan Brager applauded officials for making "great strides in cleaning up our local air quality, but ozone continues to be a challenge during our warmest months. We all need to do our part to help reduce ozone pollution."
Ransel warned that high ozone days are expected through August.
The EPA does not levy fines if the valley exceeds the standards. Instead, it gives local governments the opportunity to develop and implement plans to reduce emissions to meet the standards. Failing that, the EPA can develop a plan and force the area to comply.
"The two hammers they have is they can come in and put a federal plan on us and tell us, ‘Here’s what you’re going to do,’ and not allow industries to operate, for example, although that’s extreme, or they can limit the amount of money we can get from the fed for our highways," Ransel said. "For us, that would be a pretty serious impact."
The county’s website, clarkcountynv.gov, has the air-quality forecast on its home page. Site visitors can go to the bottom left and click on "air quality forecast."
The information is based on readings from 11 sites across the valley and four sites along transport corridors : Jean, Apex, Mesquite and Boulder City.
Weather conditions and levels of pollutants can trigger a build up of ground-level ozone, especially during afternoon hours.
Ransel suggested that work out buffs "may want to get inside and run at the health club. The ozone indoors will not be as high."
Air-quality officials encourage residents to sign up for free text and e mail advisories and air-quality forecasts through the department’s EnviroFlash service at enviroflash.org.
Contact Summerlin/Summerlin South View reporter Jan Hogan at firstname.lastname@example.org or 387-2949.