Impacts of Diesel Emissions

Diesel-powered vehicles, engines, and equipment can exhaust significant amounts of harmful pollutants like nitrogen oxides (NOx), particulate matter (PM), carbon monoxide (CO), and others into the air. NOx can further interact with volatile organic compounds (VOCs) to form toxic ground-level ozone (O3). In South Carolina, diesel-powered vehicles make up a smaller share of engines on the road, yet they contribute a disproportionally large amount of the state’s mobile source air pollution. This disproportionality in part is due to the prevalence of medium- and heavy-duty fleets—such as buses, delivery trucks, and tractor-trailers—that tend to have slower turnover. As a result, these vehicles operate with older, high-emitting engines rather than newer, pollution-controlled engines, which affect human health, our environment, and the global climate. For more information, visit the Mobile Source Pollution and Related Health Effects webpage on EPA.gov.

Human Health - Exposure to diesel exhaust can weaken our immune system and damage our respiratory tract, often triggering symptoms that may progress into asthma or other chronic respiratory illnesses. Among the pollutants in diesel emissions, PM2.5 (particulate matter less than 2.5 micrometers in diameter) is a pollutant of particular concern from its ability to penetrate deep into the lungs and potentially enter the bloodstream, where it contributes to cardiovascular risks. The health effects of diesel pollution are most pronounced in vulnerable populations, including children, pregnant women, older adults, individuals with compromised immune systems, and those with existing heart and lung disease. 

The Clean Air Task Force (CATF) provides a visual representation of the estimated damages due to diesel pollution using an interactive dashboard. Incorporating EPA data, CATF maps the estimated 8,800 deaths and nearly $1 trillion worth of monetized damages caused by diesel pollution each year. Monetized damages include but are not limited to the financial impact from increased numbers of emergency room visits, hospital admissions, and premature deaths. Click here to view this tool. 

Environment - Emissions from diesel engines contribute to the production of ground-level ozone through the combination of sunlight, NOx, and VOCs. This secondary pollutant is not only toxic to humans, but also toxic to crops, trees and other vegetation, resulting in reduced agricultural yields. 

Diesel emissions also contribute to the production of acid rain through the combination of sulfur dioxide (SO2) and NOx. Acid rain disrupts aquatic ecosystems by altering the chemical balance within soils, lakes and streams, which may have impacts on the human food chain via water, produce, meat, and fish. 

In densely populated areas, diesel emissions can contribute to reduced visibility and property damage from the formation of smog and soot. 

Diesel emissions also release greenhouse gases (GHGs) such as carbon dioxide, methane, and nitrous oxide that trap heat in the atmosphere. This contributes to climate change, which affects air and water quality, weather patterns, sea levels, ecosystems, and agriculture. New technologies can mitigate the effects of diesel emissions, like incorporating idle reduction strategies, retrofit technologies, fuel conversion kits, and modernized engines that meet emission standards. These strategies will aid in reducing the effects of climate change, improving public health, ensuring energy security, and uplifting the economy.