A fire sweeping through a New Jersey state forest this morning is affecting air quality and carrying the smell of smoke to as far away as New York City, 90 miles to the north.

The 1,500-acre fire at Wharton State Forest in Washington Township, Burlington County, is leading to hazy air and smells through Burlington and Mercer counties.

The National Weather Service says the odor is persisting this morning because the smoky air is trapped in the lowest 1,000 feet above the ground. The hazy conditions are expected to improve as the temperature rises. Emergency management officials in New York City issued an alert that people in Staten Island and Brooklyn may smell smoke from the blaze.

With light wind from the southeast, there was "just the right mix of weather conditions" for the odor to travel through the state up to the New York area, said Larry Ragonese, a spokesman for the New Jersey Department of Environmental Protection.

The department has issued an air-quality alert for central and northern New Jersey, saying sensitive groups -- like young people, the elderly and those with respiratory diseases -- should avoid strenuous activities outside.

Rain expected to fall later today should improve air quality, officials said.

The fire broke out in a remote area and has not affected any roads or buildings, according to New Jersey State Police. It's about three miles north of Batsto Village, Ragonese said. He added that the remote location made it harder for fire personnel to access the site.

Ragonese the fire was about 30 percent contained as of about 9 a.m. and was considered under control. The blaze is expected to be at least 50 percent contained within a few hours.

No injuries were reported.

Forest fires are relatively routine occurrences in the Pinelands and other state forests. Through the end of March, 167 fires had been reported in state forests so far this year, according to the state Forest Fire Service.