South Coast AQMD Issues Ozone Advisory Due to Heat Wave

The advisory is in effect through Monday evening. South Coast AQMD will issue an update if additional information becomes available

Poor air quality is expected throughout the South Coast Air Basin for Friday through Monday. Air quality will be impacted by elevated ozone levels due to a heat wave.

High temperatures are expected to persist through Monday throughout the South Coast Air Basin, increasing the likelihood of elevated ground-level ozone (smog) levels in many areas.

The National Weather Service (NWS) is predicting the continuation of a heat wave over Southern California that will last through at least Monday. The NWS has issued excessive heat warnings for most of the South Coast Air Basin. For information regarding the NWS warnings and the most current weather information, visit the NWS’ Los Angeles ( and San Diego ( websites. Elevated temperatures, which enhance ozone formation rates, coupled with predicted atmospheric inversions that trap pollution near the surface are expected to cause unusually high and persistent levels of ozone pollution.

- Advertisement -

Friday through Monday, AQI levels may reach the Unhealthy to Very Unhealthy AQI categories in the afternoon and early evening in the Santa Clarita Valley, the San Fernando Valley, the San Gabriel Mountains, the San Gabriel Valley, the Inland Empire, and the San Bernardino Mountains. Hourly AQI forecasts are available at and can be used to plan activities when the air quality is best.

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.