Counties look to diesel emissions testing for cleaner air

Saturday , February 07, 2015 - 12:00 AM

Editor’s note: This is the first in a two-part series about diesel emissions and air quality.

Weber County is looking to get diesel drivers on board to help clear the air by exploring the idea of imposing emission tests.

In inversion-prone counties, the U.S. Environmental Protection Agency requires local programs to identify high-emitting vehicles through mandatory inspections and emissions testing. The EPA, however, only requires testing for gasoline vehicles. What to do about diesel engines is up to local lawmakers to decide, at the state or county level.

“In Weber County, when we started doing emissions tests, we didn’t do diesel because of the equipment costs and the number of diesel vehicles registered in the county. The cost-benefit ratio was out of whack,” said Brian Cowan, deputy director of environmental health at the Weber-Morgan Health Department.

“But that ratio has changed significantly,” he said.

According to Weber County and Utah Department of Motor Vehicle information, the county now has around 14,571 diesel vehicles registered throughout the county. According to Cowan, around half of those are trucks with on-board technology that could allow them to be tested at existing permitted stations that already test gasoline vehicles.

“It would be easy for us to implement a testing program that inspects the light duty and medium duty diesel vehicles,” Cowan said.

During its exploratory phase, the Weber-Morgan Board of Health has consulted Davis County, where they’ve been doing diesel emissions testing for nearly two decades.

“We were the first in the state, and almost in the country,” said Mike Egginton, a manager at the county’s diesel testing center in Kaysville. He has worked at the facility since it first opened in 1996.

“We’ve always looked at it as a health benefit and it needed to be done,” he said. “We didn’t feel it was right to test the gas vehicles and impose penalties on them when the diesel guys were getting away with (high emissions).”

Salt Lake County also joined in testing diesels early on, in 1994. They require an on-board diagnostic test, or OBD, for newer light and medium duty diesel trucks.

Davis County, however, has tougher diesel tests for light- and medium-duty trucks. They use a device called a dynamometer, or “dyno” for short, which allows them to load a truck, bring it to freeway cruising speed and measure the tailpipe smoke. 

“There’s no one in the state that does a test like that,” said Dennis Keith, manager of the Air Quality Bureau at the Davis County Health Department.

By only using on-board diagnostics, which rely on a vehicle’s computer, some emissions might get missed. The OBD test also might not catch tampered vehicles, whose owners have intentionally altered them to blow a lot of smoke.

“Vehicles … have some capability with an on-board computer system, but only certain parts are monitored,” said Chuck Gee of Worldwide Environmental Products, who contracts with Davis County to operate the dyno. “So you can have a lot of problems going on.”

They also require some form of emissions testing from all registered diesel vehicles newer than 1968, including heavy-duty vehicles. Being one of the first — and still one of the strictest — counties to require diesel emissions testing, Davis officials supporting the program said they’ve felt some pushback.

“We catch a lot of vehicle owners (with high diesel emissions) who get really mad at us because if they lived in a different county, they wouldn’t be subjected to the test,” Keith said.

Those bordering counties with lax diesel policies, or no emissions testing at all, have caused other headaches in Davis County as well.

“What it does is sort of make us inconsistent,” Keith said. “People can leave our county with a truck and go to Salt Lake and get approved because they don’t have to put it on a dyno, and it puts us in an awkward position.”

To prove the importance of diesel testing throughout the state, the Davis County diesel testing center decided to conduct an experiment.

The EPA uses tiny particulates called PM 2.5, or particulate matter 2.5 microns and smaller, as measurements of air quality. A bad inversion day means high levels of these tiny particulates hover in the air, getting into our lungs and causing respiratory problems for sensitive groups.

In the summer of 2013, the Davis County facility partnered with the University of Utah to measure levels of PM 2.5 and the opacity smoke coming out of diesel tailpipes.

“We’d figured there’d be a correlation,” Gee said. “But (the results) actually came as a surprise to all of us.”

The study did find that cloudier opacity meant higher levels of particulates. What was surprising, however, was how much particulate matter a failing vehicle creates, and how fine those particles are.

According to the study, a failing diesel vehicle at the Davis County facility has more than twice the concentration of very small particles, under 0.5 microns. They had more than 17 times the concentration of particles between 0.5 and 1.0 microns, and more than 100 times the concentration of particles between 1.0 and 2.0 microns, when compared with passing vehicles.

“So these vehicles that are not passing the Davis County emissions test, they need to be corrected,” Gee said. “They are contributing way more than their fair share of the sludge we’re breathing.”

Failing vehicles, however, are usually relatively easy to fix.

“The vehicles that have failed, then came back after they’ve had tests done or work done, they’ve done some really minor fixes to their truck in order for it to pass,” Keith said, “like air filters and basic maintenance.”

Keith and Gee acknowledge their study was on a small scale. They only evaluated six vehicles over the course of two days.

“I think this summer we’re going to try again, over a prolonged period with a variety of trucks,” Gee said.

They’d also like to test for other compounds, like nitrogen oxide, which can mix in the atmosphere and form more particulates. First, however, the county needs to secure funding and equipment for the more comprehensive study.

“That hasn’t happened yet, so I can’t say for sure it’s going to happen, but we think we’ve got enough evidence to support a broader test,” Keith said. “We welcome anyone who wants to come forward and work with us.”

In the meantime, the Davis County Health Department has shared its findings at national conferences and smaller air quality meetings. They gave a presentation to the Weber-Morgan County Air Quality Advisory Committee in December.

“What I got from their study is that it’s clear diesel exhaust presents some additional health hazards that we haven’t tied to diesel exhaust in the past,” said Deputy Director Cowan. “It certainly creates the need for additional research and better understanding.”

At the most recent board of health meeting on Jan. 26, Cowan recommended moving forward with incorporating diesel testing in Weber County, making it a goal for 2015.

“Implementing a diesel emissions program we think would be a benefit to the county,” Cowan said. “The health department’s Air Quality Advisory Committee asked us to pursue this investigation, they felt it was time.”

Still, it’s unlikely Weber County will implement a testing system as sophisticated as Davis County’s dyno system. Dyno devices are expensive, around $50,000 each. An OBD test, however, can be conducted by privately owned emissions testing centers throughout the county that already do gasoline-engine tests. That means virtually no cost to the county and to county taxpayers.

“We’re just in exploratory phase right now, so the Board of Health has an opportunity to review and make the best decision for the citizens of our county,” Cowan said.

The folks running the Davis County testing center are just happy to see some consistency among the counties.

“Every county has a different health department with different programs,” Keith said. “The state want us all to be consistent, but if they want it to be consistent, they should make a state-run program, not a county-run program.”

UPDATE, March 6, 2015: This story was corrected to note Salt Lake County’s emissions testing program began in 1994. It was also corrected to note that dyno testing is only used for light- and medium-duty trucks in Davis County, not heavy-duty trucks.

Part two of this series will explore efforts on the local and state levels to snuff out smoking vehicles.

Contact reporter Leia Larsen at 801-625-4289 or Find her on or on Twitter @leialarsen

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