Air quality worsened Thursday in Baltimore area amid thick plume of Canadian wildfire smoke

Air quality sunk to “very unhealthy” levels in the Baltimore area Thursday morning as a particularly thick plume of smoke from Canadian wildfires descended on the area, worsening conditions compared to Wednesday.

With a gray-orange haze visible on the horizon and the smell of smoke in the air, many local groups canceled or modified outdoor activities for the second straight day, amid a historic outbreak of air pollution.

Public school teachers were asked to keep children indoors for the day. Parks and recreation agencies nixed outdoor events and shuttered local swimming pools. The Baltimore Ravens practiced indoors in Owings Mills, and the Maryland Zoo in Baltimore shut its gates early.

After conditions improved Thursday afternoon, National Weather Service forecasters said another dense billow of smoke could pass through the Baltimore area overnight and into Friday morning. That plume will work its way southward as the morning continues, according to the the weather service.

Showers and thunderstorms forecast for Friday afternoon as a front moves through could clear some of the smoke, said Kevin Witt, weather service meteorologist. Hazy conditions are expected to linger Saturday and taper off as the weekend continues, Witt said.

“Each day gets better and better,” he said.

But as hundreds of fires burn across Canada, the danger for continued smoke plumes remains. The wildfires already have displaced some 20,000 people, according to the Associated Press. The U.S. has sent more than 600 firefighters and equipment, and other countries also are assisting.

Air monitors across Central Maryland registered peak air quality indexes Thursday morning well above 200, and some areas climbed closer to 300, for particulate matter, according to the Maryland Department of the Environment. Any value above 300 is considered “hazardous” — the most dangerous category on the air quality index scale.

Just across the Maryland border in Pennsylvania, some levels approached 400 Thursday morning, according to MDE’s online tracker.

Though air monitors in Baltimore and along the Interstate 95 corridor were in the “Purple” zone, surpassing 200, the area remained under a less severe “Code Red” alert throughout the day. Northern Virginia and Washington, D.C., by contrast, issued a “Code Purple” warning for residents Thursday.

In a statement, MDE spokeswoman Lisa Jones said the “Code Red” decision was based on a 24-hour average of pollution concentration.

“The severity of the pollution is controlled by the weather and so changes hour by hour,” she added.

By Thursday afternoon, many air monitors in the Central Maryland had progressed from purple to red with readings under 200.

Officials continued to recommend that residents limit their time outdoors, and that of their pets, and avoid strenuous activity outside. When air quality is in the “very unhealthy” purple range, the risk of health impacts is elevated for the general public. Experts say a well-fitting N95 mask can help reduce the quantity of fine particles from entering the lungs that could cause adverse health effects.

Particulate matter is made up of fine particles of soot, dirt and smoke, and can aggravate asthma, decrease lung function, irritate airways and cause irregular heart beats. Pregnant women, children, older adults and those with existing respiratory and cardiovascular impairments are most vulnerable, and experts say there could be an uptick in patients seeking hospital care for breathing issues.

“I have had some patients call in and say that their breathing is getting a little bit worse — and these are some of my compromised respiratory patients,” said Dr. Anita Naik, a pulmonologist at MedStar Health, who works at Franklin Square Medical Center. “We’re having to increase their inhaler use, or making sure they stay indoors and wear masks and things like that.”

Baltimore has a disproportionate percentage of adults suffering from asthma: 13.7%, compared with 9% across the state and country, according to the Maryland Department of Health.

The smoky conditions also wore on Baltimore area workers who must do their jobs outside.

Outside the Sagamore Spirit distillery in Baltimore Peninsula, Frederick resident Christian Boiragee completed landscape work with his co-workers from C&C Custom Lawncare. Boiragee, 25, said he considered wearing a mask due to the air pollution, but found it difficult to breathe while he was working. But he’s noticed the impacts of wildfire smoke while on the job, he said.

“I can’t breathe, I go to sleep coughing like all night, and when I’m at work I’m just like coughing up a bunch of mucus,” he said. “I could not breathe last night when I got home.”

In Baltimore, outreach teams were canvassing the city Thursday to distribute masks to homeless people, said Kyana Underwood, spokesperson for the Mayor’s Office of Homeless Services.

The city opened a few of its “cooling centers” typically used for homeless Baltimoreans on hot days, where masks also were available. City homeless shelters were operating under a “shelter-in-place” order for residents, Underwood said.

At Beans & Bread, a Fells Point support center for homeless individuals, staff members distributed masks during Thursday’s lunch service, which drew around 200 people, said director Hendrik Schulte.

”This is affecting them the hardest,” Schulte said. “A lot of our unsheltered neighbors might be struggling with asthma, respiratory issues, high blood pressure, which puts them at risk.”

The conditions also could disproportionately impact residents with inadequate HVAC systems, said Sacoby Wilson, a professor of applied environmental health at the University of Maryland.

“Part of the problem with staying indoors is if you have a poor HVAC system, it’s not running well, you have intrusion on outdoor air inside your home,” he said.

He recommended recommended residents change in-home air filters to those with a minimum efficiency reporting value, or MERV, above nine.

Baltimore City Health Department is also giving away free masks at city-operated senior centers and four Enoch Pratt Free Library locations (Central Library, Canton Library, Orleans Library, all of which closes at 8 p.m.; and Cherry Hill Library, which closes at 7pm), though more EPFL branch locations are slated for the mask giveaways.

The smoke wave has surpassed air pollution records in Baltimore. Wednesday’s peak air quality index for particulate pollution was 165, the highest from that pollution source since a value of 169 on July 7, 2002, when Canadian wildfires also were the cause. Thursday’s numbers are poised to shatter that record.

As climate change continues to drive warmer temperatures, researchers are tracking an increase in “fire weather days” each year, where dry conditions make fires more likely and more difficult to extinguish, including on the East Coast, said Kaitlyn Trudeau, a senior research associate at Climate Center. The Baltimore area, meanwhile, is currently experiencing drought conditions amid lower than average rainfall, according to the National Integrated Drought Information System.

It’s important to remember that what’s burning in Canada is not simply trees and underbrush, Naik said, but it could also include metals, plastics and other unknown materials, sending a host of dangerous chemicals airborne.

“You’re like: ‘Oh, how bad can it be? Some wood is burning thousands of miles away.’ But it’s not that,” Naik said.

Baltimore Sun reporters Jennifer Gable, Sanya Kamidi, Dillon Mullan and Alecia Taylor contributed to this article.