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April 20, 2020   |   Diesel Technology Forum

Policy Insider

Diesel Trucks Haven’t Stopped Rolling During the Pandemic, and Now the Air is Cleaner. What Gives?

Recent decline in measured fine particles (PM 2.5) is really a story about the impacts of reduced passenger vehicle travel and gasoline consumption, not necessarily eliminating truck traffic.


For the first time in two generations, from New Delhi to Los Angeles to New York, emergency pandemic response measures – essential travel only and work at home restrictions – have resulted in dramatic air quality improvements. Why? It’s all about the traffic on the roads, and this may surprise you.  Sales of gasoline has fallen by almost 50 percent while diesel sales are down just 5 percent relative to April 2019. Over 90 percent of large trucks are powered by diesel and they have not stopped rolling during the crisis, yet the air is cleaner - how so?

Oil Sales

The recent fall in measured fine particles (PM 2.5) is really a story about the impacts of reduced passenger vehicle travel and gasoline consumption, not necessarily eliminating truck traffic. As passenger vehicle traffic has fallen, in some major metros by as much as 50 percent, truck traffic on the other hand has remained flat or ticked down modestly. As an essential service they are still delivering supplies and goods we need now more than ever. Today, more than half the nation’s truck fleet, which is mostly diesel, comes equipped with diesel particulate filters that are found to be effective in removing almost all fine particle emissions from the tailpipe. According to research published by the Health Effects Institute, trucks equipped with diesel particulate filters effectively reduce PM 2.5 emissions to levels lower than required by regulations.

A recent report from Harvard University linked higher mortality in COVID-19 patients to those living in communities with higher PM 2.5 exposure. Fine particles come from many sources including forest fires, woodstoves and agricultural dust are the leading source of emissions followed power generation and industrial boilers. The U.S. fleet of diesel trucks and gasoline cars come in at #11 and #16 respectively, according to emissions inventory data compiled by the U.S. Environmental Protection Agency.   

Today thanks to these new emissions control systems, brake dust and tire wear are the bigger sources of emissions than 2011 and newer near-zero emissions big-rig trucks.

Final food for thought... As we contemplate the post-COVID-19 era, some are calling for “green recovery” measures and policies to shift investments in transportation fuels and technologies to all electric, despite that the commercial availability of electric trucks is in a very nascent stage. EPA  estimates that the fine particle reduction of replacing an old diesel truck with either a new diesel truck or a new all-electric truck delivers roughly the same air quality impact. There are many different shades of green, and we are going to need all of them to recover our economy and quality of life.   



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Key Contact

Ezra Finkin
Director, Policy
efinkin@dieselforum.org
301-668-7230

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