Thousands of Californians urged to remain inside Wednesday

Thousands of residents across a part of California have been urged to stay indoors on Wednesday morning amid concerns over high air pollution levels, a map from AirNow shows.

As of 2.40 a.m. ET, the map shows an area of fine particle (PM2.5) pollution in the “unhealthy” Air Quality Index (AQI) category around the town of Portland, and parts of the Plumas National Forest and Sierra Valley.

When air quality reaches the “unhealthy” category, the Environmental Protection Agency (EPA) advises that sensitive groups—including young children, older adults and those with certain medical conditions—avoid long or intense outdoor activities and to consider rescheduling or moving activities indoors.

The general population is advised to reduce long or intense activities, and to take more breaks during outdoor activities.

This is a developing story. More to follow.