Air Quality
Seasonal Advisory for Ozone is in Effect

Seasonal Advisory for Ozone is in Effect

Clark County Department of Air Quality (DAQ) issued a seasonal advisory for periods of elevated ozone concentrations occurring through September. Air Quality officials will continue to monitor conditions and will post an update on the forecast page of the DAQ website if needed. The website also contains data on current and past conditions.


New Ozone Standard & Seasonal Advisory: The U.S. Environmental Protection Agency adopted a new standard for ozone in Oct. 2015 at an eight-hour average of 70 parts per billion (ppb). A part per billion is the equivalent of a drop in an Olympic size swimming pool. Clark County met the previous standard at 75 ppb but is expected to struggle with complying with the new, lower standard, especially during the spring and summer months in the Las Vegas Valley. A seasonal advisory for ozone pollution is in effect from April through September, meaning that observed levels could reach the level of the standard. Alerts are issued when unhealthy levels of ozone for sensitive groups are occurring or are imminent.

What is Ozone? Ozone is a gas that occurs naturally in the upper atmosphere and protects earth from the sunís harmful ultraviolet rays. At ground level, ozone is a key ingredient of urban smog during the hottest months of the year in Clark County. 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 transport, wildfires and fireworks. Unhealthy doses of ground-level ozone can reduce lung function and worsen respiratory illnesses such as asthma or bronchitis. Exposure to ozone also can induce coughing, wheezing and shortness of breath even in healthy people. When ozone levels are elevated, everyone should limit strenuous outdoor activity, especially people with respiratory diseases. If you are experiencing breathing difficulties or medical conditions that you think are related to air quality, see your doctor. The following tips help reduce the formation of ground-level ozone: Fill up your gas tank after sunset. Try not to spill gasoline when filling up. Donít top off your gas tank. Keep your car well maintained. Use mass transit or carpool. Donít idle your car engine. Mow your lawn after sunset.