Wildfire smoke from Canada will likely last the workweek in Philly, but air quality should improve
Wildfire smoke was helping raise ozone to hazardous levels.
No alerts have been issued, but the air quality may approach “code orange” levels again late Thursday afternoon in parts of the region, as it appears that the ozone factory will still be operating while the Canadian wildfire smoke persists in the skies over Philly.
At least the smoke “probably won’t be as noticeable” Thursday and Friday, as more actual clouds have become evident, said Alex Staarmann, meteorologist with the National Weather Service Office in Mount Holly.
Air-quality levels did reach the “code orange” unhealthful levels in Philadelphia and its neighboring Pennsylvania counties late Wednesday afternoon, and that could happen again late in the day, according to AirNow, a partnership of government and air-monitoring agencies.
The culprit would be ground-level ozone, brewed by a combination of warmth and the smoke.
During code orange conditions, those with respiratory, heart, or related issues are advised to limit outdoor activity.
In South Jersey, however, air quality remained “moderate” on Wednesday and likely will again Thursday, according to AirNow.
Staarmann said that the contrasting forecasts likely were related to differences in wind directions between the two sides of the Delaware River.
What causes ozone, and what’s the outlook for Thursday?
Ground-level ozone is not to be confused with the benign variant that helps protect Earth from harmful ultraviolet radiation.
Prime ingredients for ground-level ozone include vehicle emissions and solar heat, something the region was experiencing Wednesday.
Although the Delaware Valley Regional Planning Commission has held off on a code-orange alert for Thursday, the forecasts see ozone levels in the higher ends of the moderate range.
The smoke goes on. The primary pollutants, such as particulates, that smoke releases into the atmosphere, can help produce ground-level ozone “through complex chemical processes that are still not fully understood,” according to NOAA scientists.
The American Lung Association notes that research has documented that smoke that is days old and far away from its source can still promote ozone formation.
On Wednesday, the blazes in the Canadian woodlands were concentrated in the south-central part of the country, but acreage also was burning in extreme southern Ontario, west of Lake Erie, according to Natural Resources Canada.
Through Friday, the acreage that had burned to date was double the average.
When will the Canadian wildfire smoke finally exit?
It appears that the smoke locally will survive the workweek, said Staarmann.
“By Saturday,” he said, “it will be gone for good.”
Even it was still around, chances are excellent it would be well-obscured by clouds. Showers are likely Saturday, and after two more steamy days, temperatures are expected to be topping out in the mid- to upper-70s.
The region still awaits its first 90-degree reading, said Staarmann, and that’s about two weeks behind schedule.
Not that any wind-chill advisories are up for Thursday and Friday, with forecast temperatures both days well into the 80s, with increasing mugginess.
Staarmann said it’s even possible that the elusive 90 could happen Thursday.
But the highs the last two days have been a degree or so below forecast, and that may be related to the sunlight-scattering smoky veil, said Staarmann’s colleague Nick Guzzo.
That veil’s days do appear to be numbered.
Good riddance.