Heat warning is in effect through Tuesday morning, in many parts of LA County.

South Coast AQMD will issue an update if additional information becomes available.

High temperatures are expected to persist over the next several days throughout the South Coast Air Basin, increasing the likelihood of Unhealthy to Very Unhealthy air quality in many areas. Levels of ground-level ozone (smog) – the predominant summertime pollutant – are likely to reach the Unhealthy to Very Unhealthy level in the Santa Clarita Valley, the San Gabriel Mountains, the San Fernando and San Gabriel valleys, the Inland Empire and the San Bernardino Mountains.

Press Release...

While poor air quality is not unusual during summer months in the South Coast Air Basin, the National Weather Service (NWS) is predicting a heat wave over the Southwest that will last through Monday. This is due to a stationary upper air high pressure system located over the Four Corners area of the southwest U.S. The NWS has issued a heat advisory for the Inland Empire area of San Bernardino and Riverside Counties, which is in effect from 10 am Friday until 8 pm on Monday. The NWS has also issued an excessive heat warning for the Coachella Valley, which is also in effect from 10 am Friday until 8 pm on Monday. Elevated temperatures, which enhance ozone formation rates, coupled with predicted atmospheric inversions that trap pollution near the surface may cause unusually high and persistent levels of ozone pollution.

When air quality is Unhealthy and reaches an air quality index (AQI) range of 151 to 200, everyone may begin to experience some adverse health effects, and residents with higher sensitivity to air pollution may experience more serious effects. When air quality is Very Unhealthy with an AQI range of 201 to 300, everyone in the region may experience more serious health effects. Ozone air pollution can cause respiratory health problems, including trouble breathing, asthma attacks, and lung damage. Research also indicates that ozone exposure can increase the risk of premature death. Children, older adults, and people with asthma or COPD may be more sensitive to the health effects of ozone.

Areas of direct impacts and unhealthful air quality may include portions of:  Los Angeles County: West San Fernando Valley (Area 6), East San Fernando Valley (Area 7), West San Gabriel Valley (Area 8), East San Bernardino Valley (Area 9), Pomona-Walnut Valley (Area 10), Santa Clarita Valley (Area 13), San Gabriel Mountains (Area 15)  Orange County: Northern Orange County (Area 16)  Riverside County: Corona-Norco (Area 22), Metropolitan Riverside County (Area 23), Perris Valley (Area 24), Lake Elsinore (Area 25), Temecula Valley (Area 26), Anza Valley (Area 27), Hemet-San Jacinto Valley (Area 28), San Gorgonio Pass (Area 29), Coachella Valley (Area 30), East Riverside County (Area 31)  San Bernardino County: Northwest San Bernardino Valley (Area 32), Southwest San Bernardino Valley (Area 33), Central San Bernardino Valley (Area 34), East San Bernardino Valley (Area 35), West San Bernardino Mountains (Area 36), Central San Bernardino Mountains (Area 37), East San Bernardino Mountains (Area 38) South Coast AQMD Advisory updates can be found at the following link: http://www.aqmd.gov/advisory To subscribe to air quality alerts, advisories and forecasts by email, go to http://AirAlerts.org To view current air quality conditions by region in an interactive map, see http://www.aqmd.gov/aqimap

Air quality forecasts are available at http://www.aqmd.gov/forecast For a map of South Coast AQMD Forecast Areas, see http://www.aqmd.gov/ForecastAreas What To Do When Air Pollution Reaches Unhealthful Levels: Unhealthy for Sensitive Groups: Air Quality Index (AQI) is 101 - 150. Although the general public is not likely to be affected at this AQI range, people with heart or lung disease, older adults and children are at a greater risk from exposure to air pollution. People with heart or lung disease, older adults, and children should reduce prolonged or heavy exertion. Unhealthy: AQI is 151 - 200. Everyone may begin to experience some adverse health effects, and members of the sensitive groups may experience more serious effects. People with heart or lung disease, older adults, and children should avoid prolonged or heavy exertion. Everyone else should reduce prolonged or heavy exertion. Very Unhealthy: AQI is 201 - 300. Everyone may experience more serious health effects. People with heart or lung disease, older adults, and children should avoid all physical activity outdoors. Everyone else should avoid prolonged or heavy exertion.