Smoke drifting from ongoing wildfires has prompted New York City officials to issue an air quality alert, advising more than 10 million residents to remain indoors.

The fire, which began Tuesday in Ocean County, New Jersey—near the coastline—has now scorched over 15,000 acres. Located about 54 miles south of New York City, it is only partially contained. Officials say full containment may not be possible until rainfall expected this weekend.

The smoke, which contains harmful particles and toxic chemicals, poses serious health risks. It can trigger asthma, increase the likelihood of heart attacks, and contribute to long-term conditions such as cancer and dementia.

On Thursday, the New York State Department of Health and Department of Environmental Conservation issued a health advisory for fine particulate matter, in effect from midnight to 11:59 p.m. These particles, known as PM2.5, are incredibly small—less than 2.5 micrometers—and can lodge deep into the lungs, causing significant health problems.

The advisory applies to all five boroughs of New York City, as well as Westchester and Rockland counties and Long Island.

In addition to PM2.5, wildfire smoke contains polycyclic aromatic hydrocarbons (PAHs), which are linked to genetic mutations that may lead to cancer.

Due to elevated particle levels, the National Weather Service (NWS) warned that the Air Quality Index (AQI) in the city could exceed 100—a level considered “moderate” but still risky for vulnerable groups such as children, the elderly, and those with respiratory or cardiac conditions.

At these levels, people may experience symptoms like shortness of breath, coughing, and eye or throat irritation.

“When pollution levels are elevated, the New York State Department of Health recommends that individuals consider limiting strenuous outdoor physical activity to reduce the risk of adverse health effects,” the NWS alert reads.

Although no injuries or fatalities have been reported, the Associated Press noted that 12 structures were still at risk as of Wednesday night, after a commercial building and several vehicles were damaged.

“This fire is still very active,” said Shawn LaTourette, commissioner of the New Jersey Department of Environmental Protection. “As we continue to get this under full control, the expectation is that the number of acres will grow and will grow in a place that is unpopulated.”

An investigation concluded the fire was sparked by a poorly extinguished bonfire and labeled as “incendiary.” On Wednesday, 19-year-old Joseph Kling of Waretown was charged with Aggravated Arson and Arson in connection to the wildfire.

“At approximately 9:45am ET Tuesday, the Cedar Bridge Fire Tower located a column of smoke coming from the area of Jones Road and Bryant Road in Ocean Township,” according to the New Jersey Forest Fire Service.

Emergency crews located the fire within the Forked River Mountains Wilderness Area. Further investigation revealed Kling had ignited wooden pallets and left the area without ensuring the fire was out.

“Kling was taken into custody at Ocean Township (Waretown) Police Headquarters; he was thereafter transported to the Ocean County Jail, where he is presently lodged pending a detention hearing,” the statement said.

Following evacuations, about 5,000 New Jersey residents have now been cleared to return home.

The dry spring weather—common in New Jersey this time of year—likely worsened the fire’s spread. Sparse foliage, low humidity, and strong winds all contribute to high wildfire risk, especially during what is now peak season. A recent drought further intensified the dry conditions.

Forest Fire Service Chief Bill Donnelly reported that New Jersey has already experienced nearly twice as many wildfires in 2025 as it had by this time last year—662 fires burning over 16,500 acres.

Authorities say this is the most severe wildfire in nearly two decades, second only to a 2007 blaze that destroyed 26 square miles.