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Environmentby Laura Fay1:02 pmJun 29, 20230

Baltimore’s air quality reaches hazardous levels as wildfire smoke returns

In parts of the city and the region, monitors are showing higher “very unhealthy” levels, with increased health risks for everyone

Above: Smoke from Canadian wildfires darkens the sky over the Johns Hopkins East Baltimore medical campus, viewed from Monument Street. (Fern Shen)

Baltimore woke up to hazy skies and chalky air this morning, as the city once again recorded hazardous Code Red air quality readings due to smoke from the Canadian wildfires. 

According to the federal government’s AirNow real-time monitoring site, the AQI (Air Quality Index) in Baltimore at noon today was 186, which is considered “unhealthy for all groups.”

The pollutant of concern – fine particulate matter (PM 2.5) – is the same compound that plagued the city two weeks ago

AQI, measured on a scale from 0 to 500, approximates air quality compared to state and federal air quality standards.

An AQI of 100 is acceptable. Anything above that standard means sensitive groups – such as children and those with respiratory issues – may experience more serious health effects.

air quality airnow baltimore 6 29 23 screenshot

ABOVE: The official Air Quality Index readings in Baltimore today ware in the “unhealthy” high 100s. BELOW: Other air monitors in the city and region show even higher readings in the “very unhealthy” 200s. (airnow.gov/purpleair.com)

air quality baltimore 6 29 23 purpleair

Shifting Winds

After smoke from the Canadian wildfires left the city two weeks ago, it traveled up to the Midwest, where it has lingered since. Northwest winds, however, are now pushing the pollution back towards the Mid-Atlantic.

AQI readings in the Baltimore region have steadily increased over the last two days, with PM 2.5 levels deemed “unsafe for sensitive groups” yesterday.

But as the rest of the pollution rolled in overnight, the Maryland Department of the Environment (MDE) issued a Code Red, meaning the air quality is unsafe for all residents. 

The crowd-sourced air monitors of commercial sites, like PurpleAir, showed individual readings in the region that were even higher.

Monitors in south, east and west Baltimore registered AQI levels above 200 today, meaning the air there is Code Purple, considered “very unhealthy” with the risk of health effects increased for everyone.

MDE’s Air Quality Forecast forecast the scenario this way this morning: 

“As high pressure moves overhead into Thursday morning, calming winds and surface inversions will act to trap and concentrate smoke at the surface, while at the same time the most concentrated portions of the smoke plume move in from Pennsylvania,” the MDE forecasters said.

“As a result, concentrations of PM 2.5 due to smoke on Thursday morning will be notably elevated.”

Dissipating Friday

PM 2.5 is a particularly dangerous compound due to its ability to travel deeply through the body and get lodged in the lungs and bloodstream, inhibiting respiratory function. The smoke is also expected to enhance existing ozone concentrations. 

MDE recommends that all citizens, especially those with pre-existing respiratory conditions, limit outdoor exposure and wear a high quality (N95 or KN95) mask if outside. 

The city health department’s Twitter account today retweeted MDE’s guidance and noted that free masks are available at city-operated senior centers and library branches.

During the previous air quality emergency earlier this month, the city opened day centers for residents to shelter in place and distributed masks to homeless people and outdoor workers.

If forecasters are correct, some relief is on the way – they say the latest front of smoke should blow through relatively quickly.

Winds are expected to turn southward as early as Friday, though the air quality may remain unhealthy for sensitive groups through the day.

PM 2.5 concentrations are expected to decrease to moderate levels by Saturday morning.

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