This may seem obvious to anyone who has ever followed a diesel bus up a steep hill, but the air quality several feet away from motor vehicle lanes is significantly cleaner and healthier, according to a new study by PSU researchers.
Researchers set up P-trak instruments on the driver and passenger sides of a car parked between general traffic and the city’s new separated bike lane on SW Broadway to measure the number of particles in the air. The study concluded that there is a statistically significant difference in air quality on the separated bike lane side. From their conclusion (excerpted by Bike Portland):
The findings of this study show a cycle track roadway design may be more protective for cyclists than a traditional bicycle lane in terms of lowering exposure concentrations of ultrafine particles… Based on these initial findings, understanding roadway and traffic effects on exposure levels can help guide bicycle facility design and pinpoint locations in which mitigation of exposure levels by placement of facilities such as cycle tracks may be most important.”
This is yet another advantage to separated bike lanes that is often left out of discussions. Especially when climbing, air quality is important. There are few things less pleasant (and unhealthy) than taking a deep inhale of motor vehicle exhaust. The list of health advantages of riding a bike is long, but the extra exposure to exhaust is not one of them.
Back when we were debating the Dexter separated bike lane plans, most concerns centered around the potential dangers of riding quickly in a separated facility going downhill. Those concerns are still worth considering. However, one advantage of having a parking-separated lane on the uphill segments would have been decreased exposure to exhaust during the moments people are breathing the heaviest. Perhaps it’s not the most important safety detail, but it’s worth including in the equation when discussing different styles in the future.
When I used to live near 42nd and Fremont Ave, I would ride on the sidewalk near B.F. Day instead of the bike lane when going uphill on Fremont Ave:
For one, it is a wide sidewalk, so my slow-going bike was not a problem for people walking. It is also prettier over there (and the trees provide cover from the rain). But most of all, the air is just so much better. Taking a deep breath feels and smells fresh. It’s a short, pleasant break from clouds of exhaust from the 5 or from an old, broken car working hard to make it up the hill.