Air advisories address different types of pollutants

Mother Nature is unpredictable.

With a slight change in weather, typical clear blue skies can become dusty or smoggy in a matter of hours.

The Las Vegas Valley experiences three primary air advisories: dust, smoke and ground-level ozone, according to Phillip Wiker, air quality monitoring manager with the Clark County Department of Air Quality.

“We only deal with the pollutants in the air,” Wiker said. “There are three primary advisories, but we can have combinations of the three, as well.”

Dust and smoke are considered particle pollutants, which are divided into coarse and fine particulates. Particle pollutants can be stirred up by or emitted from unpaved roads, fires, construction sites, sand storms, power plants and automobiles.

Ground-level ozone is a form of oxygen that is the main component of smog. It is created in the atmosphere by sunlight interacting with organic compounds and nitrogen oxides.

“We have a seasonal ozone advisory that we issue April through September each year,” Wiker said. “During the summer months, you’re likely to see elevated levels of ground-level ozone.”

New Year’s Eve and the Fourth of July also typically cause air advisories because of the fireworks displays, according to Wiker.

“These advisories are pretty unique to the valley because we have generally still weather,” Wiker said. “With fireworks, you can also get precursors that can actually cause a problem with ozone levels and not just smoke.”

County officials measure air quality with the Air Quality Index issued by the U.S. Environmental Protection Agency.

The index is divided into six stages: good, moderate, unhealthy for sensitive groups, unhealthy, very unhealthy and hazardous.

Local advisories aren’t issued until the AQI reaches an unhealthy-for-sensitive-groups level, according to Wiker. This level typically applies to children, seniors and individuals who experience respiratory illnesses, such as bronchitis or asthma.

Wiker said the general public normally does not experience health effects until the AQI reaches unhealthy.

“It’s kind of tricky because we don’t instantly issue advisories once they hit an unhealthy-for-sensitive-groups-level,” he said. “For ozone advisories, it has to be at that level for eight hours. For dust and smoke, we have be exposed for 24 hours.”

Wind and heat play strong roles in air advisories, according to Chris Stumpf, National Weather Service meteorologist.

“Dust advisories typically occur when we experience very strong winds,” Stumpf said, “but ozone can become trapped in lower atmospheres on hot days when we have no wind to blow it out.”

While summer is known for its dog days, Stumpf said spring and fall are fairly windy seasons.

“During the summer, the jet stream is much farther north,” Stumpf said. “In the spring and fall, it moves down south, bringing more systems through the valley.”

During advisories, officials recommend that residents limit heavy exertion or prolonged exposure outdoors, keep windows closed, change indoor air filters and wear masks while working outdoors.

Dust can be reduced by driving slowly on unpaved roads, avoiding shortcuts across vacant lots, riding off-road vehicles in approved areas and fencing off or covering barren property.

Ground-level ozone can be limited by filling gas tanks after sunset, carpooling, turning off electronics when not in use, avoiding gas spills and running errands in one trip.

“Primarily, the air quality for this size of a metropolitan area is really good year-round,” Wiker said. “However, the hotter and stiller it gets in the summer, the more likely we’ll be issuing air advisories.”

For more information, visit airquality.clarkcountynv.gov.

Contact Southwest View reporter Caitlyn Belcher at cbelcher@viewnews.com or 702-383-0403.