Don’t Bike Until the Air Clears

But if That's Not an Option, Go Slow and Get the Right Kind of Mask, say Experts

EPA's map of air quality for the Bay Area today
EPA's map of air quality for the Bay Area today

Government officials are warning people to avoid outdoor activities (see above map) due to particulates in the air. The media is full of reports and interviews with experts about the hazards of breathing the smoke. Many schools are closed. The San Francisco Bicycle Coalition has cancelled or postponed several outdoor events, including its pop-up outreach, and its AIDS/Lifecycle Kickoff ride.

Air quality experts are warning against bike riding altogether. Many cyclists have decided to take Muni. Apparently, that’s causing huge delays.

In an interview with KRON4, Dr. Robert Blount, an assistant professor of pediatric and adult pulmonology and critical care medicine at UC San Francisco, recommended that if you have to go outside–to bike to work, for example–make sure to wear a tight-fitting “N95” mask, which means it blocks out 95 percent of particulates in the air. It should be certified with a stamp from the National Institute for Occupational Safety and Health (NIOSH). A kerchief or a run-of-the-mill dust or surgical mask won’t do–only “N95 masks, when used properly, help filter fine particulates in wildfire smoke,” wrote David C. Ralston, with the Bay Area Air Quality Management District, in an email to Streetsblog.

To be clear though, nobody is recommending you ride your bike, even with a mask, if there’s any way to avoid it. “The N95 might be good if there’s nothing else you can do, but it’s not a great solution. It’s not designed for people doing exercise or sports. It’s meant for slow, regular breathing,” said Ralph Borrmann, also with the Bay Area Air Quality Managment District. Studies show that keeping your speed and exertion levels down helps–so if you absolutely have to ride, try to stay under 11 mph and avoid hills.

Streetsblog Los Angeles, a city that knows a thing or three about dirty air, has some additional thoughts on cycling and smoky conditions back from 2009, when they suffered their last round of punishing fires. It too advises cyclists, at least when the air is this smoky, to leave the bike at home.

“I would normally ride my bike to work. I took the train instead,” said Borrmann.

If you are going to ride, it's helpful to keep speed down, and add a NIOSH-certified mask to your kit
If you are going to ride, it’s helpful to keep speeds down, and add a NIOSH-certified mask to your kit
  • JB

    🙁 Not all of us have alternatives. My commute is 15-20 minutes on a bike or about 1 hour via Muni; heck even walking is about 20 minutes faster than Muni.

  • Easy

    I wonder what the quantified risk of riding due to the fire-related air quality is, compared to every day car exhaust air quality, or the risk of being hit by a car or truck.

  • This has been studied extensively. You bike behind cars, you do get exposure to their exhaust, but the people in the interiors of those cars are exposed to several times as much exhaust.

  • NoeValleyJim
  • nolen777

    The EPA’s air quality site this morning said “moderate”, so I did bike this morning. I’m sure it was OK for me, but it was still unpleasant, and I see it’s since been downgraded to “unsafe for sensitive groups.” Be careful!

  • I understand the concern. Still, I have continued to have my daily run and have cycled regularly during the past week. Activities I have engaged in since 1971.I have not felt any obvious physical effects after engaging in these activities. Perhaps there will be long term effect to my well being. Time will tell. I do not own a motor vehicle and do not contribute to the everyday ongoing pollution.

  • Easy

    What I meant was the experts saying “don’t bike” is not very helpful.

    Saying something like “with an AQI of Unhealthy, you breathe in 5 times more particles than the average day” would be helpful. If it’s 2x an average day, I’d probably still bike. If it’s 10x I definitely wouldn’t.


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