The Toxicity of Diesel Exhaust: Implications for Primary Care

Irina N. Krivoshto, BA; John R. Richards, MD; Timothy E. Albertson, MD, MPH, PhD; Robert W. Derlet, MD

Disclosures

J Am Board Fam Med. 2008;21(1):55-62. 

In This Article

Abstract and Introduction

Diesel fuel and the products of its combustion represent one of the toxins most commonly encountered by people living in both urban and rural areas of the world. As nations become more heavily populated, there will be increasing reliance on diesel fuel to power mass transportation and commercial vehicles, as well as heavy machinery involved in construction, farming, and mining. The majority of patients who present to urban primary care clinics and emergency departments will have had significant chronic exposure to diesel exhaust because most use and/or live near busy streets and highways. Furthermore, those who operate or work or live near diesel-powered machinery will have even more toxic exposure. Primary care physicians should be aware of the acute and chronic deleterious clinical effects of diesel exhaust. In this article we review the toxicity and myriad health problems associated with diesel exhaust.

The compression-ignition diesel engine was invented by Rudolph Diesel in 1892 as an alternative to the spark-ignition gasoline engine.[1] The engine's popularity expanded because it had excellent fuel economy and durability and it required less maintenance. Diesel is the fuel of choice for use in mass transportation vehicles such as trucks, buses, and trains. Diesel fuel and the products of its combustion represent one of the most common toxins to which people living in both urban and rural areas of the world are exposed. On an equal horsepower basis, diesel exhaust is 100 times more toxic than gasoline exhaust, even when carbon monoxide is considered.[2] The Environmental Protection Agency estimates truck exhaust accounts for 20% of all vehicle-produced microscopic soot and 30% of all smog-causing chemicals in the United States.[1] As for passenger cars, fewer than 1% of new American cars have diesel engines. In contrast, diesel engines power 37% of all new cars sold in Europe, with rates as high as 62% in France.[3] One reason for this discrepancy is the suboptimal quality of diesel fuel sold in the United States; roughly half of the supply has been found to be below the standards recommended by equipment manufacturers.[1]

The majority of patients who present to urban primary care clinics and emergency departments may have had a potentially significant chronic exposure to diesel exhaust because many of them live near busy streets and highways. In Japan and Europe, epidemiologic surveyors have demonstrated high acute and chronic respiratory disease morbidity rates from occupational and proximity exposure to diesel exhaust.[4] The National Institute for Occupational Safety and Health estimates millions of workers are occupationally exposed to the combustion products of diesel fuel in their respective workplaces. Diesel exhaust is a complex mixture of toxic compounds with wide variability of deleterious effects in human and animal studies. This represents a significant limitation to epidemiologic research on diesel exhaust because the over-reporting of exposure may affect study outcomes.[5] Thus, no standard for exposure limits exists at this time.

Patients most likely to be in proximity to diesel exhaust on the job and thus suffer from occupational exposure include (1) shipping, receiving, and loading dock workers; (2) bus, truck, and forklift drivers; (3) railroad workers; (4) mine workers; (5) diesel engine repair and maintenance garage workers; (6) construction site, tunnel, and bridge workers. In 2006 the California Air Resources Board estimated that diesel exhaust pollution directly accounts for 2400 deaths and, annually, nearly 3000 hospital admissions for respiratory and cardiac-related diseases, at a total cost of $19 billion.[6] Besides on-the-job exposure to diesel exhaust, patients may be exposed to diesel exhaust from myriad and commonplace sources ( Table 1 ). Primary care physicians should be aware of the acute and chronic deleterious health effects from diesel exhaust and its potential to exacerbate other chronic disease states. We thoroughly searched medical and scientific literature databases to identify those articles that specifically addressed the relationship between diesel exhaust pollution and illness. Here we review the myriad health problems associated with this commonly encountered substance.

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