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Curbing Toxic Diesel Exhaust
by Susan Mates

Diesel engines are economical, powerful, and durable, so they power most of our equipment and move 80% of all freight. But diesel engines also emit large amounts of toxic air pollutants and ultra-fine particulate matter, about 70% of which is black carbon particulate. That makes diesel exhaust significant as a global warming contributor. Diesel particulate matter also adheres to harmful chemicals in the air and efficiently delivers them into the lungs. Those particles easily enter the bloodstream, damage lungs, worsen asthma, and cause early deaths.

The intersection of Highway 26 and 217 are hot spots for diesel particulates. GIS Map by Michael Egge, PhD student, & Andrea Richards, graduate student, both Portland Sate University. Data compilation by Greg Bourget & Alissa Leavitt. All data online at portlandcleanair.org in Data under Pollution Reports

The Environmental Protection Agency's last three-year assessment ranked the Portland Metro area in the worst 1.3% of counties for diesel particulates nationwide. Here in Washington County, residents near the Sunset Highway and Highway 217 experience some of the worst airborne diesel particulate concentrations in Oregon. This is due to 24-hour truck counts as high as 2,200 on Sunset Highway and 1,100 on Highway 217.

The good news is that trucks from model year 2010 or newer remove up to 95% of diesel particulate emissions. Older trucks can either be retrofitted with filters that remove particulate matter, or their engines can be replaced with newer model engines to achieve that standard.

The bad news is that, since both California and Washington State have much stricter regulations than Oregon, those older trucks are now being used in Oregon where the regulations are more lax. According to ODOT and DMV records, 75% of the trucks in the Portland area are unfiltered.

With recently-passed House Bill 2007, we are now taking the next steps to remedy that. The new bill requires truck owners to replace older diesel engines with newer models by 2025. Originally, it was intended to apply statewide, but the bill was scaled back in compromises to ensure its passage. The amended version applies the provision only to Multnomah, Washington and Clackamas counties, and allows heavy-duty trucks to use engines dating back to 2007. Still, it will address the diesel issue where it is the worst, and provides a framework that we can continue to improve.

“This legislation is an important step forward for our community,” said Rep. Rob Nosse, a chief sponsor of the legislation and longtime proponent of clean diesel legislation. “For too many, especially those who are low-income and the most vulnerable, pollution can have detrimental and even deadly consequences. There is still more work to be done for the state of Oregon, but House Bill 2007 will make a difference.”

Meanwhile, keep in mind that on a summer day in the Portland area, cars and trucks produce about 198 tons of smog-forming pollutants. The next time you are stuck in traffic, think of some of the many ways you might choose to drive less.

For more information, see the Diesel Reports on the Portland Clean Air site.

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