Excessive levels of air pollution risk creating "ground level" ozone. UV light from the sun activates ozone precursors, which are produced by fossil fuel combustion and electronic equipment such as photocopiers, printers and shredders. Ground-level temperatures then rise significantly as ozone naturally retains heat. Also, ozone gas in high concentrations can cause severe respiratory illness and is particularly dangerous to asthma sufferers if combined with a high pollen count.
Particles of solid matter, in the case of city pollution, usually are a form of carbon suspended in a pollutant gas and are a factor in determining the climate of New York. Large amounts of particulates absorb or disperse sunlight, which then cools or raises the ground level temperature. Additionally particulates can impact cloud formation. More numerous and smaller water droplets form around the fragments of solid matter and thus decrease the chances of rain leading to drought.
Sooty carbon deposits called black carbon can have a small but significant effect on the New York climate, particularly in winter. When black carbon settles on snow and ice, it reduces the naturally light-reflective properties of the white surface, instead causing the absorption of light and heat. The snow and ice then melt faster than they otherwise would, which in turn decreases the reflective surface area and the city as a whole absorbs more heat and the temperature rises.
On a more worldwide scale, but still indirectly effecting the temperature in New York, the enormous levels of vehicle, industrial and electrical equipment pollution created by such a major metropolis can contribute to a climate phenomenon known as "global dimming." Sulphites and nitrates rise into the troposphere, and water droplets form around them. These droplets are reflective and thus reflect sunlight away from the earth's surface, causing a drop in surface temperatures. This affects wind patterns, water currents and many other factors that determine the earth's climate.
