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Diesel Exhaust and Lung Cancer

In a move that should command the attention of Laborers, the World Health Organization (WHO) has determined that diesel exhaust causes cancer and has reclassified diesel fumes from “probably carcinogenic” to “known carcinogen.” The agency says exposure to diesel exhaust is a source of lung cancer, increases the risk of bladder cancer and is more carcinogenic than secondhand cigarette smoke.

Simple Ways to Reduce Exposure to Diesel Exhaust*

  • Reduce Idling: Decreasing engine idling reduces emissions and saves fuel.
  • Replace/Repower/Rebuild: Retire vehicles or engines “early” and replace them with new, cleaner engines or rebuild and upgrade engines to incorporate cleaner technologies.
  • Retrofit: Install retrofit equipment or muffler replacement devices to reduce emissions. These include diesel oxidation catalysts (DOCs) and diesel particulate filters (DPFs)
  • Refuel: Use a cleaner diesel fuel.

*Diesel Engine Retrofit in the Construction Industry: A How To Guide, (Massachusetts Department of Environmental Protection).

WHO elevated diesel’s status after completing a review of several studies. Of particular interest was the Diesel Exhaust in Miners Study, a project of the National Cancer Institute (NCI) and the National Institute for Occupational Safety and Health (NIOSH). Researchers focused on underground mines because heavy mining equipment often runs on diesel fuel and because exhaust concentrations tend to be higher in mines. More than 12,000 miners were evaluated, and adjustments were made for the impact of smoking and other confounding factors.

The study found that the degree of risk was affected by both exposure level to diesel fumes and whether or not miners smoked. It showed that those with the highest level of diesel exposure were three times more likely to die of lung cancer than those who had been least exposed. Among never smokers, the high exposure risk was seven times higher than the risk at low exposure.

Diesel is a more efficient fuel than gasoline, and the construction industry uses more diesel engines than any other sector. Unfortunately, however, diesel combustion produces more particle emissions than gasoline, which harms air quality. The higher this concentration, the greater the risk of lung and heart disease. According to the Northeast Diesel Collaborative (NEDC), diesel-burning backhoes, cranes and bulldozers are responsible for over 30 percent of all nitrogen oxide and fine particle emissions from mobile sources. Industry groups are making efforts to reduce diesel exposures.

A 2002 NIOSH-funded study that examined diesel exhaust exposures in the construction industry cited increased incidents of chronic bronchitis and other obstructive airway disease among bridge and tunnel workers. This study found that fourteen percent of its samples exceeded permissible exposure limits set by the American Conference of Governmental Industrial Hygienists (ACGIH). The highest exposures were among operating engineers and installers of drop ceilings and wall tiles in tunnels. Improvements in engine design and retrofitting older models with pollution control devices have led to cleaner burning of diesel, but heavy construction equipment remains a source of air pollution and diesel exhaust.

WHO has not offered guidance as to what level of diesel exposure is carcinogenic, but it does recommend efforts to reduce inhalation of diesel fumes. Laborers should take precautions and minimize their exposures.

Meanwhile the U.S. Environmental Protection Agency (EPA) continues to classify diesel as a “likely carcinogen.” The agency says more studies are needed to determine diesel’s health risks.

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