It is believed that as much as 10 billion metric tons of chloride enters the air mass through permeation each year, but just a tiny fraction does anything but fall back to the surface. The bit of chloride lingering in the air can react with nitrogen oxides, formed when fuel is burned at high temperature, to form nitryl chloride, a forerunner of chlorine atoms, the most reactive form of chlorine. Those atoms can contribute to smog formation in coastal areas.
Now, in a surprise, researchers have found that this chemistry thought to be restricted to sea spray occurs at similar rates in air above Boulder, Colo., nearly 900 miles away from any ocean. What's more, local air quality measurements taken in a number of national parks across the United States imply similar conditions in or near other non-coastal metropolitan areas.
