NEW YORK CITY – A northerly to northwesterly flow that ushered in rounds of smoke during the workweek could relax over the July 4th weekend, leading to an improvement in air quality readings.
The unhealthy air caused health advisories to be issued for many communities and more than 120 million Americans were put under Air Quality Alerts on Thursday, and unhealthy levels of air quality lingered across much of the inland Northeast, Great Lakes, and mid-Atlantic states early Friday morning.
Washington, Pittsburgh, Philadelphia, Cleveland, Detroit and Milwaukee all had AQI readings over 150 early Friday morning, with readings around or just under 150 in the New York City area.
Meanwhile, air quality was significantly improved Thursday night and Friday across much of Illinois south of Chicago, Indiana, western Ohio and Kentucky after Thursday’s ferocious winds associated with a derecho cleaned out the atmosphere.
Even with the help from the derecho, Cleveland woke to smokey skies on Friday where air quality alerts remain in place across northeast Ohio.
Hazy skies had returned to New York City Thursday, and FOX Weather senior meteorologist Greg Diamond said the smoke moved in quickly, and there was a campfire-like smell in the air.
Air Quality Index values did not reach levels experienced earlier in the month when records were set due to the thick smoke, but still exceeded 150, which is considered unhealthy levels.
Observation sites in the NYC metro reported an AQI of greater than 400 in June, setting a new modern record for the poorest air.
Where is the smoke headed?
According to forecast models, Friday could be the final day of thick smoke for the Northeast and Great Lakes before the latest round starts to thin over the weekend.
The worst AQI values are expected to be found over Pennsylvania and upstate New York. Altoona, Pennsylvania had an AQI just over 200 Friday morning, signaling "very unhealthy" air quality.
The AQI scale starts at 0 and runs to 500, with values of 50 or below representing cleaner air and values over 300 considered to be hazardous.
For some communities on Friday afternoon, AQI readings may drop into the unhealthy range, and health experts warn individuals should their limit outdoor activity to reduce effects.
Sensitive health groups may experience respiratory problems and difficulty breathing.
"As we get into your Saturday morning, you can start to see the smoke disperse even more with maybe a slight haze in the sky," said FOX Weather meteorologist Kelly Costa.
More than 120 million Americans were under air quality alerts on Wednesday due to the smoke as alerts stretched over 1,000 miles from Iowa to Massachusetts and down through the Carolinas and Georgia.
Cities such as Chicago, Indianapolis, Cleveland, Pittsburgh and Philadelphia all experienced poor air quality and reduced visibility.
Some of the poorest Air Quality Index readings were in Northeast Ohio, where several communities reported an AQI value above 300 at one point.
Reductions in visibility couldn’t come at a worse time for passengers, as AAA expects record travel for the Independence Day weekend.
Canada’s Toronto Pearson International Airport reported delays of more than an hour on Wednesday, which included many flights to the U.S.
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