Dozens of children with asthma returned home from their school near the explosion site in Manhattan Thursday morning amid warnings from the Department of Health that high winds had kicked up smoke and debris.
Mayor de Blasio said the Department of Environmental Protection is monitoring air quality around the smoldering rubble, and the Health Department was recommending residents in the immediate area limit time outside and keep their windows closed.
"If you're right on the site or a block away in any direction, the air quality is something -- you should avoid it if you can," de Blasio said.
Some 40 students with asthma went home Thursday from P.S. 57, about two blocks away from where the two buildings exploded and collapsed a day earlier, spewing ashy debris for blocks.
The Health Department said the main concern is particle pollution produced by burning debris.
The school was working with families and handling each student on a case-by-case basis, the DOE said.
Officials said air pollution from the fire should not affect healthy people, but could bother the elderly, children or sick people.
Authorities have been testing for asbestos in the air and "there is no indication" of it at this point, the mayor said.