The fire, extinguished Sunday, caused a chemical reaction when the sprinkler system activated, mixing hazardous material on site and releasing it into the air.

For everyone sheltering in place, the best practice is to turn the air conditioning off and keep windows and doors shut,” a statement said.

A shelter-in-place order remained in effect Monday in parts of greater Atlanta after a chemical fire at a pool cleaning facility shot plumes of black smoke into the air, forced evacuations and closed roads, including a main traffic vein into the city.