Nova Scotia wildfire smoke not entirely to blame for poor air quality in Northeast
A “code orange” air quality alert was issued for all of New Jersey and Pennsylvania on Wednesday. AccuWeather forecasters say the smoke from wildfires in Nova Scotia is not the only thing creating the poor air quality across the Northeastern U.S.
More than 16,000 people were forced to evacuate their homes in Canada’s eastern province of Nova Scotia, officials said Monday, as one of hundreds of wildfires raging across the country threatened the city of Halifax.
Raging wildfires in western Canada have sent plumes of smoke across the northern United States over the past several weeks. But a new cluster of wildfires in Nova Scotia, Canada, has brought a higher concentration of smoke to parts of the Northeast this week. The recent plume of smoke, combined with the persistent high-pressure system parked over the Northeast, prompted air quality alerts for at least two states in the Northeast.
On Wednesday, the National Weather Service (NWS) issued a "code orange" air quality alert for all of New Jersey and southeastern Pennsylvania, including the Philadelphia area. This alert means air pollution concentration in the region may become unhealthy for sensitive groups, including young children and adults over 65. The alert warned people in sensitive groups to limit their time outdoors.
But AccuWeather Senior Meteorologist Dan Pydynowski says the smoke alone isn't creating the poor air quality across the Northeast.
Smoke from the wildfires in Nova Scotia spreading over parts of the northeastern United States. (Credit NOAA/CIRA)
"Most of the wildfire smoke has been in the high levels in the Northeast and mid-Atlantic, so the greater impact on air quality [on Wednesday] and the next couple of days will likely be man-made ground pollutants [and naturally occurring pollutants] like ozone thanks to a hot, stagnant air mass," said Pydynowski.
The persistent high pressure that has been parked over the Northeast and Midwest this week has not only been fueling the hot, summerlike weather but also air stagnation.
This snapshot captures the air quality across the northeastern United States on Wednesday morning. Poor air quality can be seen in the yellow and orange colors. Green and blue indicate better air quality. (AccuWeather)
Air stagnation is a meteorological term that explains when air pollution in a certain area is built up in the atmosphere.
"This usually occurs when the same air mass is parked over the same area for several days," according to the NWS glossary. "During this time, the light winds cannot 'cleanse' the buildup of smoke, dust, gases, and other industrial air pollution."
Pydynowski explained that ground-level ozone is typically worse during the summer months because the amount of sunlight during the day is at its highest.
Hazy skies can be seen on the New York Harbor EarthCam on Wednesday morning. (EarthCam)
"Another factor is less wind, more stagnant air masses allowing the ozone to form near the surface and not be scoured out," said Pydynowski. "Winter has more wind and much shorter day lengths."
The most notable impact of the wildfire smoke will be the hazy skies it will produce across the Northeast, according to Pydynowski. Sunrises and sunsets may give off a reddish hue, as well.
The color of the sky has to do with how the sun's light, or wavelengths, is scattered in the atmosphere. Shorter wavelengths, such as blue, are reflected by the smoke particles. The smoke particles don't reflect the longer wavelengths, such as red. So to our eyes, the sunrise and sunset will appear a vibrant red.
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