Problems in Big Cities
Environmental issues in New York City are affected by the city's size, density, abundant public transportation infrastructure, and location at the mouth of the Hudson River. New York City also plays an important role in national environmental policy because of its size and influence.
New York's population density has environmental benefits and dangers. It facilitates the highest mass transit use in the United States, but also concentrates pollution. Gasoline consumption in the city is at the rate the national average was in the 1920s, and greenhouse gas emissions are a fraction of the national average, at 7.1 metric tons per person per year, below San Francisco, at 11.2 metric tons, and the national average, at 24.5 metric tons. New York City accounts for only 1% of United States greenhouse gas emissions while housing 2.7% of its population.
Air pollution, while not as severe as in cities like Los Angeles or Beijing, remains a major problem. The city's air has high levels of ozone and particulates, and residents in some neighborhoods have very high rates of asthma. Pollution varies greatly from borough to borough, and residents of Manhattan face the highest risk in the country of developing cancer from chemicals in the air. Air pollution is an ongoing political issue in neighborhoods that contain bus depots.
The 2009 annual report of the American Lung Association ranks the New York City region as 22nd of the 25 regions in the United States most affected by year-round particle pollution, and 17th of the 25 most ozone-polluted cities.
The city has made efforts to reduce particle pollution with measures like fitting catalytic converters to the exhausts of diesel city buses. New York also has the largest hybrid bus fleet in the country, and some of the first hybrid taxis. A large percentage of the city-owned vehicle fleet, including the personal cars of top city officials, are required since