Cars, Trucks, Air Pollution briefing Cars and Trucks and Air Pollution program overview health and environment advanced vehicles cars and suvs trucks and buses Transportation is the largest single source of air pollution in the United States. It causes nearly two-thirds of the carbon monoxide, a third of the nitrogen oxides, and a quarter of the hydrocarbons in our atmosphere. With the number of vehicles on the road and the number of vehicle miles traveled escalating rapidly, we are on the fast lane to smoggy skies and dirty air. The Ingredients of Air Pollution Cars and trucks pollute the air during manufacturing, oil refining and distribution, refueling and, most of all, vehicle use.
Motor vehicles cause both primary and secondary pollution.
The primary ingredient in the smog, ozone is created when hydrocarbons and nitrous oxides from automobile combustion react with sunlight. Though beneficial in the upper atmosphere, at the ground level this gas irritates the respiratory system, causing coughing, choking, and reduced lung capacity. These particles of soot, metals, and pollen give smog its murky color. Fine particles, PM that is less than one-tenth the diameter of a human hair, pose the most serious threat to human health, penetrating deep into the lungs. In addition to direct emissions of fine particles, automobiles release nitrogen oxides, hydrocarbons, and sulfur dioxide, which generate additional fine particles as secondary pollution.