New York has extended its air quality health advisory to tomorrow.

The move comes as the air quality in the region is forecast to remain at "unhealthy" levels tomorrow.

The advisory was already in place today for the NYC metro area, Long Island, the lower and upper Hudson Valley, eastern Lake Ontario and the central and western New York regions. 

The pollutant of concern is fine particulate matter — which can cause short-term health effects such as shortness of breath and nose, throat and eye irritation. Exposure can also affect lung function and worsen medical conditions such as asthma and heart disease, according to the New York State Health Department. 

People are urged to stay indoors, use mass transit instead of driving to avoid contributing to emissions, and to conserve fuel and energy.

Livestreams of various points in Manhattan show just how much smoke is blanketing the city.

One stream offers a look at the Empire State Building, barely visible as of early afternoon. Another of the World Trade Center shows downtown Manhattan barely visible.

It's June 7, and that just so happens to be "Clean Air Day" in Canada.

"This is a day to recognize how important good air quality is to our health, our environment, and the economy," according to the Canadian government's website. "It was first celebrated in 1999 when Canada declared Clean Air Day an annual celebration during Canadian Environment Week."

A new NASA forecast shows just how much of the country could be cloaked in wildfire smoke over the next four days. The animation, produced by scientists at the Goddard Space Flight Center in Maryland, shows a thick plume swirling over the Northeast today and into tomorrow, with conditions improving slightly heading into the weekend.

In the coming days, the model suggests that a portion of the country stretching from the Midwest into the Southeast could also experience hazy conditions, as tendrils of smoke waft over these regions. The yellow and red colorings in the animation show concentrations of small particulate matter that is commonly found in air pollution from wildfire smoke.

The wildfire smoke creeping across the Northeast is affecting air travel today.

Departures were grounded at New York City's LaGuardia Airport “due to low visibility” until 2 p.m. ET, according to the Federal Aviation Administration. The FAA also paused flights from the Upper Midwest and East Coast bound for LaGuardia.

Newark Liberty International Airport tweeted that “current smoke condition may impact your travel, please check with your airline to determine the status of your flight.” The FAA said it was slowing flights to Newark.

Wind and haze were reported at airports in the New York City area, the Washington, D.C., metro area and Philadelphia, the FAA said Wednesday in a daily air traffic report.

Samuel Ausby with the FAA Command Center said in a video shared on Twitter: “Today we’re dealing with some smoke and haze in the northeast."

"There are some fires in Canada that have been producing some smoke, due to the wind patterns it is now impacting the northeast of the U.S. so from Boston, the NY metro area, Philadelphia and the D.C. metro area — are all experiencing some smoke that could impact travel through the airports,” he said.  

So far, there have been a total of 1,147 flights delayed and 73 canceled, according to FlightAware.com.

Climate change is increasing the impact of wildfires in Canada, according to the 2019 Canada’s Changing Climate Report, the country’s national assessment of climate impacts. 

“It’s not really the number, it’s mostly the size of the fires,” said Xianli Wang, a fire research scientist with the Canadian Forest Service, whose work is cited in the report. “Fires are larger and more intense, and we see a lot more fires burning through the night,” which makes them more difficult to control.

Wang said climate change is increasing the length of the fire season in Canadian provinces and increasing the likelihood of fire weather. Modeling suggests that trend will continue and expand as the climate warms, Wang added. Historic policies that prioritized fire suppression also have allowed fuels — dried vegetation and logs — to build up on the landscape in many areas, increasing fire potential.  

“If you don’t have a lot of dry, windy and hot days, fires will be quiet and fires may not grow as big as they are this year. As soon as the fire weather is ready for the fire to grow, they go crazy,” Wang said. “Climate change is definitely doing its work.”

Portable air purifiers with HEPA filters can be very effective, reducing indoor particle concentrations by as much as 85%, according to the Environmental Protection Agency.

Choose air purifiers that have a clean air delivery rate — a metric of how effective they are at removing pollutants — of at least two-thirds the size of the room they are intended for, experts say.

For most rooms, a clean air delivery rate equal to 300 or more cubic feet per minute should be enough, said Dr. Barbara Mann, a pulmonologist and assistant professor of medicine at the Icahn School of Medicine at Mount Sinai in New York.

To maximize air purifiers’ effectiveness, change their filters at the recommended intervals, she added. Keep windows closed when using them. When coming in from extended periods outside in areas of poor air quality, change clothes, take off shoes and shower, she said.

Pollutants can come from indoor sources, too, said Dr. Peter Moschovis, a pulmonologist and critical care physician at Massachusetts General Hospital and an assistant professor at Harvard Medical School.

“Don’t generate extra particles indoors if you can,” he said. “So, smoking, vaping, burning incense, aerosolized essential oils — all those things aren’t good for your lungs at baseline.”