Authorities have issued a Code Orange alert for the District for Friday.
Concentrations of smog and soot in the air are expected to reach levels that may be harmful for people with health problems.
The alert was issued by Clean Air Partners, a group that is funded in part by the Metropolitan Washington Council of Governments.
The group says young people, the elderly and those with heart or lung conditions should limit outdoor activity. They recommend that residents limit driving to reduce smog.
The D.C. area has already had six Code Orange days this year, including Thursday. Last year, there were 40 Code Orange days and three of the more serious Code Red days.
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Information from: The Washington Post
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