Internal National Park Service documents seen by The Washington Post suggest visitors should “avoid prolonged exposure” in unhealthy areas

July 4 fireworks in Washington, D.C. may cause hazardous levels of pollution around the National Mall, according to a report. ​

More than 850,000 pyrotechnic effects are set to be launched from areas surrounding the Mall, West Potomac Park and the Potomac River throughout the display, Freedom 250 says, to mark 250th anniversary of the signing of the Declaration of Independence.​

However, internal National Park Service documents obtained by The Washington Post suggest particles from firework combustion could create “very unhealthy” conditions in central D.C this weekend.​

The health warning is another potential blow to Trump’s planned celebrations, following the appearance of algae-blooms and peeling paint in the Lincoln Memorial Reflecting Pool. The commander-in-chief was also reportedly “livid” at the crowd size at his kick off event for the Great American State Fair.