Take a deep breath.
The season for ground-level ozone pollution is here, and Clark County air quality officials say they will breathe a lot easier too if everybody who drives cars, fills gasoline tanks, mows lawns or inhales air that blows toward Las Vegas from Southern California -- well, that's about everybody -- tries harder to curb smog-forming compounds.
The main culprits are VOCs, short for volatile organic compounds, also known as vapors that escape into the air from tailpipe emissions, gasoline pumps, lawn mower engines and industrial processes. Even forest fires and combustion of fossil fuels will push the county closer toward violating the Environmental Protection Agency standard for ground-level ozone.
Dennis Ransel, air planning manager for the county's Department of Air Quality and Environmental Management, said it will only take a nudge to exceed the standard of 75 parts per billion of ozone in the Las Vegas Valley's air. That would be unhealthful, unlike ozone high in the atmosphere that screens out harmful ultraviolet rays from the sun.
"During the summer months, we have higher levels of ozone and people should watch for alerts," he said about the ground-level ozone season that begins in May and runs through September.
Hot, stagnant weather conditions can sometimes increase ozone levels, irritating the lungs of healthy people and worsening respiratory illnesses such as asthma and bronchitis.
"When ozone levels are elevated, everyone should limit strenuous outdoor activity, especially people with respiratory diseases," air quality officials said .
Their advisory suggests motorists fill gasoline tanks after sunset, plan errands for a single trip, don't spill gasoline when filling up and don't top off the tank, and "keep your car well maintained. Use mass transit or carpool."
Last year, the county violated the EPA's ozone standard one day in June. The standard, based on the highest eight-hour daily average for the pollutant, is under review and could be made more stringent by lowering the 75 parts-per-billion mark down to between 60 to 70 parts per billion.
For illustration purposes, 70 parts per billion is about the same volume as one pingpong ball in 14 Olympic-size swimming pools.
That means the Las Vegas Valley and other parts of the state could become out of compliance, triggering a series of costly measures to meet a tighter standard.
At a minimum, Clark County in a few years probably will be required to submit a plan to the EPA for reducing ozone pollution that will entail such measures as requiring the sale of cleaner gasoline and boosting its smog-check and voluntary ride-sharing programs.
Failing to comply under a state plan could result in federal management of a more effective plan or loss of federal highway funding in noncompliant areas in the state .
Clark County and hundreds of other areas across the nation are expected to be designated in August as areas that violate the standard. Then the county will have until 2013 to develop a plan for demonstrating compliance.
Depending on how severe the ozone problem is, the EPA will give Clark County a time frame for compliance. More congested areas, such as those in California, will have longer periods to demonstrate compliance.
Ransel expects state and county officials will try to persuade the EPA to make exceptions for Nevada's ability to comply with the standard when smog from wildfires and pollution sources drifts into the state from elsewhere.
"We're trying to advocate that the EPA look at this from a regional perspective rather than trying to resolve it from the perspective of an island city in the desert."
Contact reporter Keith Rogers at firstname.lastname@example.org or 702-383-0308.