Heat wave expected to bring bad air quality, officials say

The downtown Los Angeles skyline is seen from Griffith Observatory on July 1.
(Christina House / Los Angeles Times)

The heat wave forecast for this weekend is expected to bring poor air quality to the region.

Air quality officials have issued an ozone advisory for the South Coast Air Basin through Tuesday morning.

Ground-level ozone — the gas in smog — will probably reach unhealthy to very unhealthy levels in the Santa Clarita, San Fernando and San Gabriel valleys; the San Gabriel and San Bernardino mountains; and the Inland Empire, according to a statement from the South Coast Air Quality Management District.


High temperatures cause ozone to form more quickly. The heat is expected to combine with atmospheric inversions to trap the pollution close to the ground, resulting in unusually high and persistent ozone pollution levels, officials said.

Ozone pollution can cause respiratory problems, including asthma attacks and lung damage. When it reaches unhealthy levels, older adults, children, and people with heart or lung disease are advised to avoid prolonged exertion. When ozone pollution reaches very unhealthy levels, members of those sensitive groups are advised to avoid outdoor physical activity altogether.

After years of improvement, ozone pollution levels in Southern California have ticked upward in recent years, particularly in inland communities such as San Bernardino.