FRESNO, Calif. (KFSN) -- Air pollution created by fireworks was off the charts Sunday night.
"When we see these spikes on the 4th of July, it really is concerning," says Jaime Holt with the Valley Air District.
The amount of PM2.5, particulate matter, soared as the celebrations got loud.
"We saw about 10 pm, our levels just go through the roof," Holt said.
The air is considered too unhealthy when PM2.5 is measured at over 75 micrograms per cubic meter.
Sunday night, the measurement in central Fresno doubled that number.
"At 9 pm, it actually went off the charts, so it went above 150," Holt said. "That's why the break is here, because it was so high."
The Air Quality Index has now returned to normal after the spike that sent some people indoors.
"Folks really notice it," Holt said. "If you're in a neighborhood where there are lots of these ground-level fireworks that are being put off, they smoke out your neighborhood."
The Valley is already home to some of the dirtiest air in the country.
Holt says the air district worries because, as we've seen the past, wildfire can also cause air quality to deteriorate very quickly.
"If we get a wildfire that brings smoke to the Valley, it really becomes a very serious health impact for all of us," she said.
We've already seen a few wildfires this season. Fortunately, crews have been able to keep them under control.