Diesel and air quality
Why do we need to act now to reduce diesel pollution from heavy-duty engines? Because it’s not only one of Oregon’s biggest air quality problems—it contributes to all of them. According to the Oregon Department of Environmental Quality’s 2017 Air Quality annual report, Oregon’s “air pollutants of greatest concern” are:
Ground-level ozone (smog):
Diesel engines are responsible for 49% of NOx (a smog-forming pollutant) from transportation. Heavy duty vehicles are the largest source of NOx emissions in Oregon. Ozone is created when NOx and VOC pollutants meet high temperatures and sunlight. According to Diesel Technology Forum, one diesel truck from 1988 can emit as much NOx pollution as 50 trucks that meet 2017 standards.
Air toxics: In addition to toxic diesel particles, exhaust contains toxic gases. Diesel is a source of both benzene and acetaldehyde, which are near or above health benchmarks in Oregon.
Climate pollution: Diesel engines emit carbon dioxide, which contributes to global climate change. In addition, about 70% of diesel particles are black carbon, which has immediate effects on the local climate. Black carbon changes the quality of clouds (altering precipitation), causes faster snow and ice melt, and contributes to warmer temperatures ( absorbing solar radiation and emitting it as heat).
Fine particulate matter (PM 2.5)
Fine (microscopic, 2.5 micron) sooty particles (PM 2.5) come from all sources of burning materials—but old diesel engines are responsible for 60% of them. Diesel particulate matter (DPM) is both part of the bigger soot problem and also considered its own uniquely toxic pollutant with its own health benchmark. Oregon’s health benchmark for diesel particulates in ambient air is set at 0.1 μg/m3 to protect people from excess cancer risk over a lifetime.
Today, 19 counties (where most Oregonians live) exceed that benchmark.