Southern California is facing a serious air-quality crisis, prompting officials to warn more than 18 million residents to remain indoors whenever possible. The alert, issued by the National Weather Service, remains in effect until midnight and spans a wide stretch of the region, from coastal cities to inland valleys.

According to the South Coast Air Quality Management District, monitoring stations detected unusually high concentrations of PM2.5—tiny particles released from traffic, industrial activity, and wood burning. These microscopic pollutants can travel deep into the lungs. Moreover, they pose significant risks for older adults, young children, and anyone with heart or lung conditions.

In response, officials announced a temporary ban on all wood burning. The order covers Los Angeles and Orange counties, along with the Inland Empire and parts of Riverside and San Bernardino. Residents may not burn wood, pellets, or manufactured logs in fireplaces or outdoor devices.

The National Weather Service urged people to limit outdoor activity. Keeping windows closed, using air purifiers, and relying on air-conditioning rather than whole-house fans can help reduce exposure. Experts also recommend checking real-time conditions on AQMD’s website or mobile app.

This week’s stagnant weather is trapping pollutants close to the ground. As a result, the haze may linger for several days. Health officials caution that even short-term exposure can cause headaches, breathing difficulties, and fatigue. Long-term or repeated exposure is far more serious.

With holiday traffic and winter fireplace use adding to the problem, authorities say additional alerts may follow. Residents are encouraged to monitor updates throughout the week and take precautions to protect their health.