It’s so hot, even the fallout from the fireworks is sluggish.
The region’s air quality alerts associated with the Fourth of July concluded Sunday afternoon. But as Southern California’s focus shifts to the sweltering heat expected for the day and the rest of the week, an expert noted that soot and particulate matter may not be dispersing normally.
The heat is affecting how air pollution disperses over the region, National Weather Service meteorologist Carol Ciliberti said Sunday.
The high-pressure system that’s causing temperature spikes, Ciliberti said, is also depressing much of the particulate matter, pushing it closer to the ground.
“If there’s a layer where there’s smoggy or particle stuff, then it’s suppressed closer to the ground, so that makes the situation worse,” Ciliberti said.
Normally, the onshore flow — a west-to-southwest wind that creates the ocean breeze and pushes air away from the coasts — would push the particulate matter with it. But today, the winds are weaker, meaning the pollution carried by the air isn’t being dispersed.
“If we had stronger onshore flow, that would help to disperse some of the fine particle pollution,” Ciliberti said. “That’s not happening.”
Some straggling celebrations were expected to continue Sunday night but would not create the same amount of pollution they did on the Fourth, Ciliberti said.
Compounding the poor air quality, this year’s celebration comes on the heels of a late June warehouse fire in Boyle Heights that released extraordinary amounts of soot and smoke across L.A. County, on par with pollution generated by the previous year’s wildfires.
An alert for hazardous air quality issued Saturday evening by the South Coast Air Quality Management District due to the soot and particulates from fireworks ended at 3 p.m. Sunday for central and southern Los Angeles County, northern Orange County, and Riverside and San Bernardino counties.
July 4 and 5 are traditionally two of the worst days of the year for the region’s air quality, according to the South Coast AQMD.