A new joint study from the city of Portland and Multnomah County throws cold water on the idea of creating a local air pollution district.

Such an agency would take power away from the Oregon Department of Environmental Quality and no longer subject Portland, the city with Oregon's dirtiest air, to the influence of conservative Salem lawmakers.

But creating a local authority could create as many problems as it solves, the study found, potentially exacerbating the state's existing air pollution permit backlog and delaying industrial inspections.

Instead, the $120,000 study written by the Good Company and Eastern Research Group suggests that Portland and Multnomah County could fund work at the Department of Environmental Quality that state lawmakers won't. And they could undertake their own air monitoring and clean air projects.

The report makes clear that city and county officials don't have to create an entire standalone bureaucracy -- equipped with new desks, new computers, new workers and new office space -- to make the region's air cleaner. Portland Mayor Ted Wheeler was the only local leader to have endorsed the idea.

Instead, they could:

Require that public construction projects only use low-polluting, modern diesel equipment. Diesel soot is one of the most ubiquitous pollutants in the region's air and poses serious health risks.

Create a grant program to create incentives for owners of diesel trucks and equipment used in the urban core to upgrade to cleaner-burning engines.

Expand efforts to clean up wood stoves.

Push TriMet to upgrade its fleet, which includes 207 diesel-burning buses built before 2007, when engines began burning cleaner.

Michael Cox, a spokesman for Wheeler, said the mayor is "examining the findings and working with Multnomah County and other partners to land on a solution that will be most beneficial to the residents of Portland."

Deborah Kafoury, chairwoman of the Multnomah County commission, said she anticipates continuing the county's push for statewide action to clean up dirty diesel engines across Oregon.

"Our job pushing the state to do the right thing is an important one," she said. "It is a role that we gladly play."

Portland had a local air district from 1967 to 1973. The idea was revived in 2017 after state legislators struggled to pass Gov. Kate Brown's proposed clean air overhaul.

Lawmakers did pass an industry-written version of Brown's plan in March. But it is a far cry from the major overhaul Brown promised in response to the 2016 crisis about toxic metals in Portland's air.

The Multnomah County Commission is scheduled to discuss the report Tuesday at 10 a.m.

&amp;amp;amp;lt;a href="https://assets.documentcloud.org/documents/4558144/Multnomah-Report-2018-6-20-2-2.pdf"&amp;amp;amp;gt;Multnomah County Air Study (PDF)&amp;amp;amp;lt;/a&amp;amp;amp;gt; &amp;amp;amp;lt;br /&amp;amp;amp;gt; &amp;amp;amp;lt;a href="https://assets.documentcloud.org/documents/4558144/Multnomah-Report-2018-6-20-2-2.txt"&amp;amp;amp;gt;Multnomah County Air Study (Text)&amp;amp;amp;lt;/a&amp;amp;amp;gt;

— Rob Davis

rdavis@oregonian.com

503.294.7657; @robwdavis