A breath of (mostly) fresh air

By Phil Swartzendruber, Ph.D., Air Quality Scientist at the Puget Sound Clean Air Agency and Cascade member

As an atmospheric scientist specializing in air pollution, riding a bike has been many things including entertainment, fitness, meditation and scientific research. My love of cycling started, like many kids, with a dirt bike on trails full of dips, jumps and bumps. I have since had many great biking experiences, including commuting everyday along a picturesque causeway in South Miami; riding the STP with my wife on a tandem; and doing some commuting on a unicycle.

On most days, however, I enjoy commuting from Shoreline to downtown using varying lengths of rides and buses. Inevitably, as a burn starts to build in my legs and I wish for larger lungs, the question returns to my mind… what did I just breathe?

Bike to Work Month this year has let the Puget Sound Clean Air Agency bring these two issues together in an innovative and local way. We developed a set of air monitoring instruments that our staff can carry on their bicycles for Air Quality Rides (AQRs). We have to use smaller, more portable instruments, which may not be as accurate and reliable as those we use at our official sites, but they still give us useful information about where things are better or worse, or if there’s a hotspot and we need to investigate further.

The air we breathe is a complex mixture that includes gases and some very small particles (known as “fine particles”) that can be a mix of solid and liquid. Most of what we breathe is mostly inert (nitrogen), helpful to us (oxygen) or helpful to plants and the ecosystem in moderate or stable amounts. But there are many other more dilute components which can have mixed effects (for example: ozone is good up high, bad in our lungs) or mostly bad effects (for example: carbon monoxide, fine particles).

Regulations coming from the Federal Clean Air Act have significantly reduced pollution from big industrial sources and from cars and trucks. We’ve made good progress but there’s still more to do! Over the past several decades, the science has become increasingly clear that air pollution can have health impacts at even lower levels than previously thought. We are moving from an era dominated by a few large sources that impact large areas, to many smaller sources that have much more localized impacts. In the Puget Sound during the summer, diesel vehicles and cars dominate the air pollution issues. In the winter, residential wood burning is the biggest source.

To keep our knowledge current, we’re developing new tools and approaches to look at the smaller scale air quality impacts in more detail. And, there’s no better way to see what’s happening on your block than to… head out around your block! Our staff doing AQRs are gathering information about their neighborhoods and bike routes.

This data will be analyzed with the hopes of finding new ideas about how to address air quality in specific neighborhoods, how we can connect with local communities, and ultimately give us direction about our continued mission to keep everyone breathing clean air. The early word on the data is mostly good. We generally see elevated fine particle pollution near I-5, in industrial areas to the south of downtown, and some more modest elevations at busy intersections. Most neighborhoods and quiet streets look good. On my first AQR, the “highest” values my instruments read was when I caught up to a cyclist who was smoking! 

Biking has a range of benefits, from the personal like keeping fit, saving gas, and avoiding vehicle commute stress, to the public benefits such as reduced pollution and congestion especially when it replaces miles driven in a single occupancy vehicle. Biking may expose you to some occasional whiffs of exhaust, but remember that sitting in your car in the middle of a congested highway exposes you to that very same pollution at its most concentrated levels.

In the end, the health benefits of biking are overwhelmingly positive, and the bike is helping us collect new air quality data!

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