Study says region's maritime sources are major air polluters

Puget Sound has been a homeport to generations of fishermen, a highway for commuters and global gateway to commerce. But that's made for a less savory contribution: air pollution.

The ships — and the trucks, trains and cranes that haul away their cargo — create more than a third of the region's toxic diesel emissions, the biggest regional health threat from air pollution, according to a study released Tuesday.

The findings of the Puget Sound Maritime Air Emissions Inventory are the first detailed accounting of the air pollution from maritime sources throughout the Sound. It was completed by the Puget Sound Maritime Air Forum, an alliance of maritime industries, ports and environmental regulators.

It comes as clean-air agencies, ports and the shipping industry here have been working to avoid the pollution problems that have plagued California ports, fouling the air in Los Angeles and Long Beach neighborhoods.

That pollution comes from thousands of exhausts, on everything from ferries and small personal watercraft to the hulking freighters.

The picture the report paints is one of myriad waterborne engines, plus related trains and trucks, combining to be a major contributor to the region's smog, diesel soot and a chemical that forms acid rain.

All told, the engines spew 17 percent of the nitrous oxides that form ground-level ozone, a constituent of smog. They produce 40 percent of the sulfur dioxide, which contributes to acid rain, and 36 percent of the diesel particles that are thought to raise risks of cancer as well as exacerbate asthma and heart problems.

Warren Cornwall: 206-464-2311 or wcornwall@seattletimes.com