New York suffers from some of the worst air pollution in the world. This is the reason

(CNN) — New York state officials are warning residents to avoid being outdoors due to a possible health hazard this Wednesday, as orange smog from Canada sweeps across parts of the Northeast and Mid-Atlantic regions.

New York City recorded some of the world’s worst air pollution for hours on Tuesday, due to heavy smoke from more than 100 wildfires burning north of the Canadian border.

According to the National Weather Service, the smog prompted air quality alerts in Massachusetts, New Hampshire, Pennsylvania, Maryland, Virginia and the Carolinas.

Hazardous air quality could continue into Wednesday, New York Mayor Eric Adams asked residents to limit their outdoor activities and state environmental officials to issue an air quality health advisory in the city through Wednesday.

“Active children, adults and people with lung conditions such as asthma should minimize prolonged or vigorous outdoor activity,” officials advised.

New York public schools have canceled all outdoor activities this Wednesday, but will remain open. At least 10 central New York state school districts canceled outdoor activities and events Tuesday.

Smoke from Canadian fires has continued to blanket the Northeast and Mid-Atlantic for more than a week, raising concerns about the effects of persistently poor air quality. New York City’s air quality index hit 150 on Tuesday. According to IQair“Unhealthy” pollution levels for sensitive groups such as the elderly, children and those with respiratory problems.

New York City was in the top five places with the world’s most polluted air on Tuesday afternoon, IQair reported, along with Dhaka in Bangladesh; in Jakarta, Indonesia; and New Delhi, the capital of India.

Smoke from wildfires contains very small particulate matter, or PM2.5, a small but very dangerous pollutant. When inhaled, it penetrates deep into the lung tissue and enters the bloodstream. It comes from sources such as burning fossils, dust storms and wildfires, and has been linked to many health problems including asthma, heart disease and respiratory problems.

Millions of people die every year from health problems related to air pollution. In 2016, About 4.2 million premature deaths are linked to those fine particlesAccording to the World Health Organization (WHO).

This Tuesday, the concentration of PM2.5 in the air of New York City was 10 times higher than the guideline established by the WHO.

“If you see or smell smoke, you need to know what you’re exposed to,” said William Barrett, senior national director of the American Lung Association’s Clean Air Advisory. “It’s important that you do as much as possible to stay indoors during those high pollution episodes and pay attention to your health and the development of symptoms.”

People especially vulnerable to wildfire smoke are “children, the elderly, pregnant women or people with respiratory or cardiovascular diseases,” Barrett said, whose symptoms can worsen or recur when smoking.

“Make sure you take appropriate action and consult with healthcare providers about symptoms that arise during this time,” Barrett said.

According to the Canadian Interagency Wildfire Centre, there were more than 150 wildfires in Quebec this week; More than twice the number of fires in any other Canadian province.

So far in 2023, there have been more than 400 forest fires across Quebec, more than twice the average for this year. Wildfires have burned nearly 4 million hectares in Canada so far this year, with more than 200,000 hectares burned in Quebec alone.

Air quality advisories were in effect for parts of the northeastern and midwestern United States on Tuesday, as wildfire smoke drifted west toward Detroit and Chicago.

“Weather conditions, widespread ozone or particulate matter levels are expected to exceed the unhealthy category for sensitive groups on the air quality index,” the National Weather Service in Chicago said. “Active children and adults, especially those with lung or respiratory conditions such as asthma, should limit prolonged outdoor activity.”

Detroit appeared on a list of the 10 worst places for air pollution, according to IQair on Tuesday afternoon. Air quality in Chicago was mild Tuesday afternoon and is expected to remain moderate for the next few days.

Meanwhile, Pittsburgh’s air quality remained at unhealthy levels, before neutralizing again on Wednesday, with forecasts showing little change to unhealthy levels for sensitive groups on Tuesday. The city is currently under an air quality alert, which has been in effect since Tuesday.

New York and parts of New England will also be under an air quality warning on Tuesday, including most of New York state and all of Massachusetts, Connecticut, Rhode Island and Vermont. Cities including Baltimore, Boston, Hartford, Providence and Montpelier in Vermont are forecast to have unhealthy air quality for sensitive groups on Tuesday.

A cold front is expected to move south over the next few days, carrying smoke south and east throughout the week.

Human-caused climate change has exacerbated hotter, drier conditions, allowing wildfires to spread and increase. Wildfires in the western U.S. and Canada that have burned millions of acres in South Carolina can be blamed on carbon pollution from big cement and fossil fuel companies, scientists said recently.

When they burn, smoke travels thousands of miles downstream, endangering millions.

“Forest Fires Are the Most Global Warming Problem” Glory Dolphin Hammes previously told CNN, CEO of IQAir North America. “They have a lot to do with climate change, which creates fundamentally unsafe conditions.”

CNN’s Robert Shackelford, Jennifer Gray and Monica Garrett contributed to this report.