Exposure to Diesel Particulate Pollution in Connecticut

Exhaust from diesel trucks and buses is a leading source of harmful air pollution that sends Connecticut residents to the hospital every year. Though medium and heavy-duty trucks and buses make up only 6 percent of the state’s 2.4 million vehicles on the roads, they contribute a disproportionate 53 percent of nitrogen oxide (NOx), 45 percent of fine particulate matter (PM2.5), and 25 percent of global warming emissions from all on-road vehicles.

Diesel exhaust contains a cocktail of toxic air pollutants that have led it to be deemed a Group 1 carcinogen by the World Health Organization. This includes NOx which irritates the heart and lungs and worsens the effects of asthma, especially in children and the elderly. NOx then further reacts in the atmosphere to form PM2.5 and ground-level ozone (soot and smog). PM2.5 is responsible for 63 percent of environmentally caused deaths in the US, and has been linked to premature death, increased hospital admissions for heart and lung diseases, bronchitis, and worsening of asthma and chronic obstructive pulmonary disease (COPD).

This pollution costs the state hundreds of millions of dollars and many lives lost. The map below shows how on-road diesel pollution from trucks and buses is concentrated in certain areas of the state, usually at the nexus of truck routes and other goods movement infrastructure (ports, warehouses, railyards, etc.). Diesel pollution exposure is especially high along I-95 and I-91 corridors passing through communities such as Stamford, Norwalk, Bridgeport, New Haven, and Hartford. Other hotspots in the state center around other high traffic corridors, for example at the intersection of I-84 and CT-8 in Waterbury, and along I-395 passing through Norwich. These hotspots overlap with the state’s communities that are already overburdened by the cumulative impacts of other environmental risks, social determinants of health, and socioeconomic vulnerabilities (see designation of environmental justice communities in Connecticut and an upcoming mapping tool developed by University of Connecticut and CTDEEP).

One promising route towards addressing toxic diesel pollution is the adoption of electric trucks and buses, which are available and ready today in most use cases and produce no tailpipe emissions. Transitioning to electric trucks and buses will not only allow Connecticut residents to breathe more freely, but will also cut down on climate pollution, save money for truck and bus fleets, and result in lower electricity bills.

Strong federal, state, and local policies are necessary to ensure a rapid and equitable transition to electric trucks and buses. A first step is adopting the Advanced Clean Truck (ACT) rule, a first-of-its kind regulation that requires manufacturers to sell an increasing percentage of electric trucks per year. Acknowledging the history of disproportionate air pollution impacts in Connecticut, the ACT is only a first step of many that are necessary to guarantee pollution reductions in the communities that need it the most. Now is the time for Connecticut to step up its climate and clean air leadership.