Thousands of residents in California and Oregon have been advised to remain inside amid concerns over high levels of air pollution.

The Environmental Protection Agency's (EPA) AirNow map shows that air quality is in the "unhealthy" range for an area around La Pine in Oregon, and Portola in California on Tuesday morning.

Why it Matters

Officials and experts say that deteriorating air quality heightens health risks for vulnerable populations , such as older adults, children, and individuals with respiratory illnesses.

When pollution is in the "unhealthy" range, the EPA advises that sensitive groups avoid long or intense outdoor activities and consider moving or rescheduling them indoors. The EPA also recommends the remainder of the population to reduce long or intense activities,

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