You might be able to get some fresh air in Manhattan — if you hang out in Central Park all day. Otherwise, the hazards of breathing city air change just about as quickly as it takes for your Uber to arrive at your destination, according to a new study from MIT Senseable City Lab.

The MIT team came up with a new tool for determining the air-quality conditions and exposure hazards of different areas of the city: cellphones.

Using cellphone data collected from New Yorkers over 120 days, and focusing on the prevalence of PM2.5 (a specific noxious particle) at different times of day, the researchers found that New Yorkers who live and work in Manhattan are exposed to more toxic pollution than residents who leave their Manhattan jobs and go home to the far reaches of the outer boroughs.

“Exposure indices are vastly different during the day and night in New York City. This is due to the people moving in and out of the urban center for work and other activities,” the study said.

Therefore, previous studies fall short of telling the whole story about exposure to air pollution and health risks.

The MIT research shows that the highest concentrations of PM2.5 particles in Manhattan and areas directly across the East River in Brooklyn and Queens. Most of the Bronx is also afflicted with high levels of PM2.5.

"PM2.5 is a fine particulate matter of diameter less than 2.5 micrometers. These tiny dust particles, when inhaled, lead to numerous health conditions including early death, and heart and lung related illnesses," they study said.

Globally, 3.7 million deaths were attributable to ambient air pollution, according to the World Health Organization. And the single biggest risk to the health of New Yorkers is air pollution and the myriad diseases it causes, including stroke, lung cancer, acute lower respiratory infections, COPD and coronary artery disease.

Nyhan said her research could be used if New York wanted to go down the path of “low emissions zones,” as London has done. Motorists driving in most areas of Greater London have to pay a daily charge unless their vehicles meet European emissions standards, she told The Guardian.

“By overlaying live environmental data with live transportation data, we can modify our transportation systems, modify our traffic through adaptic and intelligent traffic signaling to reduce emission, and reduce air pollution concentration levels in extremely targeted areas,” said Nyhan.

Therefore, environmental policies should not be static, but rather dynamic, so that they respond to episodes of pollution as they occur and move, Nyhan asserts.

Mayor Bill de Blasio set a goal for New York to have the cleanest air of any U.S. city by 2030, pledging to cut PM2.5 levels by 50 percent in the next 14 years by replacing city vehicles running on petroleum and diesel with electric ones, phasing in clean sources of electricity, and staying on the vanguard of energy efficient buildings and urban spaces.