The dust from car tires is killing coho salmon, significantly reducing local populations of the vital fish species. This isn’t exactly news, but Q13 recently ran a story about one test for a roadway stormwater treatment concept using compost and sand that is worth a watch.
The effort is specifically targeting a chemical in tires that is used to reduce wear called 6PPD. Cars leave this chemical on the roadway as dust whenever they drive, and it eventually washes into the waterways and combines with ozone to become a mostly unknown chemical called 6PPD-quinone. This chemical is fatally toxic to coho salmon (and surely other species as well). The focus on this one toxin is thanks to findings published in December 2020 by a team of UW and WSU researchers. Here’s their video from 2020:
It’s not clear how much it would cost to install enough of these filters to scrub the chemical from our waterways, but it is surely a significant undertaking. The report also notes that environmental groups are pressuring tire makers to find a replacement for this chemical, and I hope legislators are aware that industry groups will not likely take such an action unless forced to.
But what the report leaves out is that people can also drive less. If your car isn’t rubbing its tires on the road, then they won’t leech this dust or any of the other toxic chemicals spewed from tailpipes or scraped from brake pads and tires into the ecosystem. Driving is a very damaging activity.
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6 responses to “Driving kills salmon”
Wouldn’t bike tires and bus tires also contain 6PPD? Though the load on bike tires may be much less, their psi is much higher than car tires.
Sure bicycle tires do get wear, as do bus tires, but the relative amount of dust created per passenger mile on a bus is miniscule when compared to Single Occupancy Auto’s . The contact surface area of a bike tire when compared to an auto is tiny so the pollution is also porportionally less. My shoes probably have this stuff in their soles too, but I have been wearing them for nearly a decade when I walk to the store or other destinations. Our choices do matter and I hope we all began to make better ones.
I really doubt that King County buses have great passenger usage rates since COVID. Especially with some bus lines notorious for crime and people smoking fentanyl actually on the bus. Buses may have other value regarding social equity, but I don’t see them as necessarily greener.
Roughly I expect to get 5000 miles out of a pair of bike tires. Car tires is more like 50,000 miles. I’m not sure I follow your argument. I would expect a larger contact patch to result in less wear on the tire.
I’d much rather see an argument around eliminating 6PPD entirely then making up “fake science” that is contorted to make cyclists feel smug. It’s too bad that the tribalists slam on Cliff Mass so much; he is more right than wrong most of the time.
Even within the realm of driving, I would expect the standard driver habits that improve energy efficiency to also reduce tire dust. This means driving slower on the freeway, avoiding jackrabbit starts and stops, choosing a smaller car over a bigger car, and keeping the tires properly inflated.
Are we seriously debating bike tread wear (for me: 180 lbs for bike plus rider) with car tread wear (3500 lb for average sedan)? Let’s do the math:
From Tire Rack:
MICHELIN CROSSCLIMATE2 on a Toyota Camry (215/55R17):
Tread depth new: 10/32, at replacement: 4/32 => 6/32 or 4.76 mm
Tread width: 7.1″ (180.3 mm)
Rolling diameter: 26.3 (688 mm)
Circumference: 566.5 mm
circum * width * depth: 1,855,000 mm3
divide by 50,000 miles: 37 mm3 / mile
Bicycle tires have a much wider range in size, but let’s try my commuter bike: 700c x 32 mm
Diameter: 622 mm + 2 * 30mm = 686 mm
Circumference: 2155 mm
Tread wear depth * width: 1.5 mm * 4mm (an estimate, but likely high)
circum * width * depth = 12,930 mm3
divide by 5,000 miles = 2.58 mm3 / mile (I get ~4,000 on rear, ~8,000 on front)
More than an order of magnitude.
The other thing on top of this is that beyond personal choices, when we build cities around biking, walking, and transit use, we travel shorter distances on average than when we build cities around private cars. We mostly see the benefits of sustainable transportation through collective choices.