NEW YORK — A new study shows that a recent surge in pollution in the U.S. may be responsible for the spike in the number of premature deaths in the nation’s cities.

It also highlights the challenges that residents face in trying to keep air quality high.

The study by the American Lung Association and the University of Wisconsin-Madison and published Wednesday in the Journal of the American Medical Association, found that the U,S.

has been adding more pollutants into the air over the past decade than ever before.

We have to start taking measures to keep our air clean, and this is not just a problem in the West, it’s a problem for cities as well, said Dr. Paul Kocher, lead author of the study and a professor at the University at Buffalo School of Public Health.

In addition to the number and type of pollutants added, many pollutants are concentrated in the air in a small area of the city, and the amount of time it takes for them to travel from one pollutant source to another, said Kocger, who is also director of the Center for Environmental Health at the university.

So far, the U has been making significant strides to reduce air pollution, but that won’t be enough, he said.

“We need to do more to reduce pollution from source to source, and we need to take action from source — both at the individual and at the community level.”

The study looked at pollution levels from the city of New York, and it found that in the past 10 years, the average concentration of carbon monoxide has jumped by nearly 10 times, the concentration of nitrogen dioxide has risen by nearly four times, and nitrogen dioxide levels in the atmosphere have doubled.

Nitrogen dioxide levels are also the highest they’ve been in nearly 30 years.

At the same time, the amount and concentration of pollutants in the city are decreasing.

For example, in 2010, the pollution levels in New York City were around 30 times the amount they were in 2008.

Now, the levels are about 20 times less than they were at the same point in the 1990s, the study found.

That’s not good, said lead author Kocmer.

While New York has had a major effort to reduce its pollution levels, that has not been enough, said Tom McLean, president of the New York chapter of the Council on Environmental Quality.

“It’s time to take a step back, recognize that our air is getting worse and look at how we can get even better, and really work on our city’s air quality,” he said in a statement.

There are several ways to reduce the amount, intensity and duration of pollutants, he added.

McLean said it is important to work together to find solutions to the problem.

He called for state and local governments to work more closely with cities, businesses and other entities that are impacted by pollution.

“If we don’t, the problem will continue,” McLean said.