Diesel exhaust is responsible for three major types of pollution: air toxics, soot and smog. These problems can lead to negative health effects ranging from headaches and upset stomachs to chronic respiratory illness and cancer.

A study by the Union of Concerned Scientists has found that 9 out of 10 of America’s 454,000 school buses are powered by diesel, meaning that children who take these buses are exposed to a considerable amount of pollution on a regular basis.

One study found that "23 to 46 children out of every 1 million who ride a school bus will someday get cancer as a result of their exposure to diesel exhaust." More common, however, are the frequent asthma attacks resulting from diesel exhaust. In smoggy urban areas, asthma attacks are now the leading cause for missed school days.

What’s more, children are typically more susceptible to the effects of air pollution than healthy adults. Their lungs are young and still developing, and children also tend to have higher breathing rates and spend more time outdoors than grown ups, exposing them to even greater amounts of pollution.

Several studies have found that kids living near highways and other busy streets have worse lung function than children living in cleaner locations. Some environmental groups have pointed to the fact that diesel bus depots are often placed in poor communities of color -- evidence of what is known as "environmental racism." Often times children in these neighborhoods have less access to healthcare than children from richer families, which can exacerbate the health problems caused by their environment.

Luckily, realistic alternatives to diesel are currently on the market. Many cities and towns are replacing old, diesel-powered buses with buses that run on cleaner-burning compressed natural gas or zero-emissions fuel cells. Groups like the Union of Concerned Scientists and West Harlem Environmental Action are involved in campaigns to replace dirty diesel buses with alternatives that are safer for our children’s health.