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Diesel Pollution
Last revised: August 20, 2003
Health Effects Associated with Diesel Emissions:
Soot
Particulate matter, commonly referred to as soot, is made up of small particles that are covered with compounds formed during the engine combustion process and that travel through the exhaust pipes. Diesel engines are responsible for as much as half of all soot found in many urban areas. The release of soot occurs with diesel engines because of the high sulfur content in diesel fuel, poor refinement processes, and incomplete combustion of fuel.
Airborne soot gets trapped in the lungs and can cause tissue damage and exacerbate existing lung problems and can cause new ones. The California Air Resources Board and the World Health Organization have both declared soot from diesel exhaust tailpipes to be a human carcinogen, and scientists increasingly believe that soot is the most deadly type of air pollution. In addition, a recent Johns Hopkins study found a link between death rates and the incidence of fine particles in the air of 20 of America's biggest cities.
Scientists blame soot for 64,000 premature deaths per year in the US, which is almost twice the number of deaths due to auto crashes. Soot causes bacterial and viral respiratory infections like pneumonia, as well as chronic lung diseases like asthma that destroy lives over the course of years. In addition, studies have found that soot may cause heart attacks and arrhythmia (irregular heart-beat) and that the incidence of strokes and heart failure is greater in areas with high levels of soot.
Smog
The nitrogen oxide emitted by diesel engines plays a large role in the formation of ground-level ozone, commonly referred to as smog. Smog is formed when nitrogen oxide reacts with volatile organic compounds and sunlight to become a colorless, odorless gas. Because sunlight is required in the production of smog, smog levels are at their highest in the summer months and in states with warm weather. It is estimated that more than 100 million Americans continue to breathe air that doesn't meet health-based smog standards.
Nitrogen Oxide + Volatile Organic Compounds
+ 
= SMOG
When inhaled, smog causes a burning of the cell wall of the lungs and air passages. This eventually decrease the elasticity of the lungs, making them more susceptible to infections and injury and causing asthma attacks and other respiratory illnesses. This danger is present for anyone who inhales smog, although children, elderly, and those with respiratory problems are at a higher risk of developing health problems associated with smog pollution. Children take in more air for their body weights than adults, and their bodies are still developing, putting them at higher risk from air pollutants. A UCLA School of Medicine study found that over time, repeated exposure smog and other air pollutants can cause as much damage to the lungs as smoking a pack of cigarettes a day. In addition, a recent Abt Associates study found that high smog levels in the eastern US cause 159,000 trips to the emergency room, 53,000 hospital admissions, and six million asthma attacks each summer.
Cancer
More than thirty studies have linked diesel exhaust to cancer. A report by the Natural Resources Defense Council found that about one in every 2,000 people may develop cancer due to a lifetime exposure to diesel exhaust at the outdoor average concentration. According to a recent study, the exhaust levels on school buses were more than eight times the average levels found in the smoggy air in California. This exposure can result in 23 to 46 additional cancer cases per million children exposed.
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