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Clean Air Agency expands picture of Seattle air quality using devices mounted on bikes

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Heather McAuliffe with her pollution-sniffing instruments mounted on her bike. Photo from McAuliffe.
Heather McAuliffe with her pollution-sniffing instruments mounted on her bike. Photo from McAuliffe.

The Puget Sound Clean Air Agency has been experimenting with a new way to gather a more complete picture of Seattle’s air quality conditions: Attaching measuring instruments to their bicycles.

In a February report for Seattle Bike Blog by Ryann Child, we told you about a UW study where researchers biked a black carbon measuring device in a loop around the city. The results were somewhat stunning because it showed big spikes in pollution levels in sometimes surprising locations. And it raised more questions than it answered. Specifically: What about the rest of the city?

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Heather McAuliffe is a Fremont resident who rides a bike to get around and is passionate about air quality issues.

“I grew up here, and when I took my first airplane trip when I was seven I remember flying in and out of Seattle and I could see the pollution,” she said. “People’s health depends on clean air.”

So McAuliffe researched and purchased a particle monitor, GPS and GoPro camera set up, and the Puget Sound Clean Air Agency offered to analyze her data. McAuliffe works for Seattle’s Departments of Neighborhoods, but took on these efforts in her free time. Several PSCAA employees also bought the bike-mountable air quality devices and used them to collect data during May’s Bike Month.

The PSCAA has “robust” air quality information from some stationary devices and industry data sources, but they do not have anything the gets granular down to the block-by-block level.

“As the science has been growing and evolving, there continues to be new tech and new instruments that let us see more,” said PSCAA Air Resources Specialist Phil Swartzendruber. So while they have good data on a handful of fixed locations around the region, “What happens on each block and each neighborhood where people walk and people bike and people kayak?”

And, importantly, the instruments are getting cheaper and more portable. The particle measuring instrument they used costs about $400. “In terms of a scientific tool, that’s quite cheap,” he said.

A more accurate instrument could cost in the $20,000 range and would be harder to transport. But the bike-mounted experiment represents a somewhat crude snapshot of some air particles known to be harmful to people’s health.

The results of the experiment and the cost of the instruments has the agency considering what a bigger and more complete data gathering process could be possible in the future.

“Is this something we could loan out to people?” asked Swartzendruber, suggesting that the agency could some day give people the chance to effectively check out the measuring devices to collect data where they live and work and return it to the PSCAA for analysis.

But don’t hop on your bike and head down to the PSCAA offices just yet, as they do not have the plans or infrastructure to engage the public like this yet. But if you are super interested in the idea, you can contact spokesperson Kit McGurn to chat about how or whether you can help.

What they have found so far

The biggest thing they have learned from this experiment is that this does seem to be a good way to gather data. But there is some useful data for people who bike (or walk or, you know, breathe).

First, the big intersection of Dexter, Westlake, Nickerson and the Fremont Bridge really does stand out as a problem area. This was also noted in the UW study, so it seems that area does have significantly worse air quality than most other areas of the city measured so far.

I asked why this might be, and Swartzendruber could only speculate that it has to do with so many busy streets converging and the fact that the area has a lot of idling vehicle engines, which are known to produce a lot of harmful pollution. In fact, the worst vehicle pollution is often emitted as the vehicle starts up from a stop.

Another area where you are likely to encounter larger-than-normal pollution levels: Downtown.

“In downtown, levels almost always went up,” said Swartzendruber. Again, this is likely due to lots of traffic and lots of idling vehicles.

But lest you see this data and get worried about so much red in the map, researchers cautioned people not to read too much into the map’s color coding.

“We didn’t witness anything that was really concerning in the first place,” said Swartzendruber. They also said it’s a little difficult to say exactly what these somewhat crude measurements are saying about the air quality’s effect on health. There are many sizes of fine particles in the air, for example, and the instruments only measure some of them. And the color scale chosen is just to show changes in the dataset. So it’s not like “red” means you’ll experience Beijing or even Los Angeles levels of pollution. But it does show that some kinds of pollution are higher than in other areas.

And though people on bikes are sometimes exposed to higher-than-normal levels of pollution, the benefits of biking still outweigh the negatives from pollution according to the PSCAA website:

Preliminary data from Seattle and other cities suggests bike riders may have short-term exposures to higher levels of pollutants in the city. The best current scientific evidence, however, suggests that the benefits of riding greatly outweigh the much smaller risk of short-term pollution exposure.

McAuliffe hopes the data collection leads to a bigger conversation about the effect of air quality and vehicle pollution on people’s health.

“I want the city to take more seriously the consequences of mixing people near heavy traffic,” she said. And having more data may help us do that.

How does the air quality for some kids’ walk or bike routes to school compare to others? How is the air quality on the school playground? How about the park? How about the neighborhood’s commercial street? How does income or race correlate with a person’s exposure to pollution? What kinds of bike routes and bike facilities have better or worse pollution exposure? Does road design have an impact on pollution levels measured on the sidewalk?

There are a lot of questions left to answer, so I hope PSCAA does pursue this effort to expand our city’s air quality map to the block-by-block level.

If you are eager to start taking measurements yourself and have some cash to invest in the effort, here’s a list of the devices they are using:

In other bikey air quality news, a Portland researcher recently found that people biking 11 mph are exposed to less dangerous pollution that people going other speeds, especially if they are not on busy streets.

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22 responses to “Clean Air Agency expands picture of Seattle air quality using devices mounted on bikes”

  1. Andres Salomon

    And here’s another one:


    People in cars & buses are exposed to much higher levels of pollution as particulates in air get trapped inside of vehicles. People who walk and bike next to those same vehicles get exposed to similar pollutants, but the lack of trapped air allows them to also get lots of fresh air. End result, much lower exposure to air pollution for people who walk & bike.

    1. Peri Hartman

      And here’s another study:

      which claims just the opposite. (Disclaimer: I didn’t watch the video – too long.) In this study, which I only skimmed, they take into account that cyclists and joggers are breathing harder and are breathing all the exhaust while at intersections, while those in vehicles are somewhat protected due to the fact that it takes time for outside air to infiltrate. They also studied the effects of riding or jogging on separate paths. Even a small separate from the traffic made a difference.

      To me, intuitively, this makes more sense.

      1. Andres Salomon

        Context is everything.

        The video I linked to is from an experiment done in London, which is about 5x as dense as Auckland. Heavy breathing/exertion was not taken into account. Also, due to the density of the city, the person on the bike managed to complete the journey the quickest, while the car/bus appeared to spend time stuck in congestion. I suspect due to the fact that the person on foot was walking (instead of running), and because the person biking didn’t have many hills to deal with, heavy breathing probably wasn’t considered a priority. The journey was roughly 20, 30, and 40 mins for biking, driving, and busing respectively.

        The Auckland study looked at a much less dense area. The travel times were an hour for the bike/runner, and 20 mins for the car. Heavy breathing/exertion was not actually measured, an equation was simply used to figure out an assumed breathing factor. The study actually found that the highest avg CO exposure was for car and bus users. However, when you then multiple the numbers by the (made up, assumed, and constant) breathing factor and the additional time it took to traverse a less dense environment, you end up with more exposure for the runner and cyclist.

        For me, the takeaway from the Auckland study is this quote:
        “This is an interesting result as it demonstrates that due to the high temporal and spatial variability in CO concentrations, other variables (such as ventilation rate and proximity to emissions) may be more important in determining exposure than choice of transport

        The reason why I’m pointing this out: as you bike through a dense, congested area, passing cars and waiting alongside them at smoggy intersections, it follows from both studies that you will be exposed to fewer pollutants than the people sitting in those cars if the amount of time you spend in traffic is similar to or less than them. That makes me feel a bit better about having to bike in those situations.

        If you have a longer, on-street commute through only lightly congested streets (as can be found in many of the less dense neighborhoods of Seattle), you will probably be exposed to *more* pollutants. In those situations, find yourself a greenway or bike trail..

        That’s my interpretation of these two bits of research. YMMV!

  2. Peri Hartman

    The number one thing the city (or state) could do to reduce air pollution is to require diesel (no disease) engines to be cleaner. Banning them altogether is a nonstarter, but producing less particulate is possible now.

    Next to the risk of getting hit on the road, the number 2 rider deterrent is probably breathing bad air behind a filthy engine.

    1. Peri Hartman

      The spelling checker corrected my play on words: diseasel.

      1. Packet

        Apparently you have no clue about any type of combustion engine and how it works. Your ignorance is completely amazing considering a Ford Focus in Britain/EU gets 57 miles to the gallon or more running diesel which due to the EPA is not allowed int he USA import market.

        There are systems already built into expensive cars that run diesel that are cleaner than gas. However your EPA is so completely backward they are not present in this country on big rigs. Instead what you have is a particulate filter that eats 1/3 of the mileage of the rig previously. Thanks to most of you for voting for more government intervention.

        Diesel gets any load a lot further on a lot less fuel. You obviously have no clue about where gasoline came from or what diesel is. Gasoline is a byproduct of making kerosene(lamp oil) a change from (whale oil). Kerosene which is not so far off of diesel.

        Its not the fuel, its you and your government that is in the way of providing cleaner fuel. Go ahead and mine the limited resources of lithium for your car batteries. There wont be enough for even 10% of the cars in the USA. Let alone it still sucks electricity powered by hydro, COAL and GAS. Try using it where there is no hydro-power, then you might understand the true cost.

        You live in a pipe dream if you think diesel is going away. The powers that be have no vision of what to do other than spend money throwing band-aids at carbon credits. They have no plan other than spending money and if you keep voting the same people in that is what you deserve.

        If you want to make a difference look into the multitude of fuels race cars use. Mainly alcohol not made by the USA government. It burns way cleaner than anything else.

        This is directed at all of you. How many of you burn scented candles? Why do you keep voting for idiots rather than helping develop new cleaner fuels? Ah I see you are not scientists but just vote for what you always have felt in your emotions the party to the left. Not chemists, not physicists, just ideologists. Please learn what is involved in changing what we burn rather than just making blanket statements of ignorance. Diesel is here to stay until you provide a more efficient alternative. You can make all the rules you want it doesn’t fix a thing. Just look at California and their budget and lack of funding.

      2. Peri Hartman

        packet – I don’t need to defend myself. There are plenty of studies showing the harmful effects of particulates in diesel exhaust. This has nothing to do with MPG or CO2.

      3. Packet

        You may think you don’t need to defend what you stated but as its based on assumptions not science you should read a little more on the actual data.

        “Many organizations have run with the studies which show a positive correlation with DPM and cancer (and apparently ignored the studies which show a negative correlation), and have published estimates of the number of cancer cases that can be attributed to DPM. However, according to the U.S. Department of Energy: these conclusions are based on the flawed
        MATES II study conducted by the South Coast Air Quality Management District (SCAQMD) in Southern California. (3) The MATES II study arbitrarily assigned 70% of the cumulative risk from air toxics to diesel particulate matter (PM) emissions. To support this conclusion, SCAQMD used elemental carbon as a surrogate for diesel PM. Although the EPA has used a similar approach to estimate levels of diesel PM in its Hazardous Air Pollutant Exposure Model (HAPEM), the agency acknowledges that this approach raises issues of the use of a gas-phase surrogate species for a particulate compound and that CO and PM emissions from mobile sources are not always correlated. Because SCAQMD did not directly measure diesel PM, it calculated diesel PM in the ambient air from assumptions based on data nearly 20 years old.


  3. Taylor

    This seems like a hack-a-thon waiting to happen. arduino(or RaspberryPI)+GPS+sensor = cool tool. Might look into getting an OEM version and hacking the other stuff onto it.

    Not as accurate as the one used here but if you got the whole toolset down in the 50 -100 range the volume of data might be worth the fuzzy resolution.

    Then again garbage in garbage out as always.

  4. Zach Shaner

    Sometimes ignorance is bliss. Ever since that 11mph story came out, I wince every afternoon when I bike over I-5 and then up Pine or Denny past traffic that is either idling or going uphill getting 10mpg. My morning commute smells good and is refreshing, but my afternoon one is always stuffy and makes my lungs hurt.

  5. Allan

    I am glad to know that people are taking an interest. I believe we were exposed to a lot of hot particles when Fukushima blew it’s lid. I think that people should have been warned to stay indoors at that time. I think that we should have the mechanisms in place to warn us of dangerous pollution levels when they happen. I also think that heavy pollution areas are not always staying in the same place. I am sure that they move about town. They would be affected by wind direction and changing sources such as the presence of large ships, temporary traffic congestion, fires, etc.

    1. nullbull

      The Fukushima reaction was more than a little overblown. Speaking as someone with a partner close to the repsonse, the amount of air monitoring equipment that was deployed in response and the amount of hype of what were massively under-whelming results (to the point of scientists asking “why are we doing this exactly?”) were highly overkill. I would worry far more about particulate and ground level ozone from cars than I would about fallout.

    2. Packet

      Sure eat some kelp if you can find some thats not contaminated in Puget Sound.
      The reality is we got very little of that radiation here, but if the wind is right we get pollution including dust storms from China. Go to Eastern WA on a good day in the right place and you can go from sun to never seeing the road much again or at all in the dust storms that can develop there. You risk more exposure to glass particles when a volcano blows or much worse when an asteroid hits the earth that what came from Fukushima to Seattle.

  6. Allan

    One of the virtues of really bright bike lights is that they show up the pollution in front of you at night. I have seen mornings where I thought I was biking into a can of Campbells Soup. Now that I am retired and no longer commuting I have not noticed so much but I had days when I would go back to put a muffler over my face to avoid inhaling the floaties in front of me. This was usually in winter but I don’t use lights much in the summer. If you have a bright light that can zoom into a pencil beam you can see a beam full of floaties and wonder what they are.

    1. Packet

      YES one of the virtues of not living in Seattle or venturing outside of it is you get away from the LIGHT POLLUTION. Not air pollution but LIGHT POLLUTION.
      Take a class in Astronomy even a short research on the subject and you might perhaps understand why you cannot see anything in the sky well here.

  7. Southeasterner

    If we could just put a value on those emissions as far as health care costs, economic loss, etc.. we may have a way to price in a very much ignored externality related to operating a vehicle.

    Similar to smoking, if you get the insurance companies involved and people with respiratory issues living near heavily traffic areas start heading for the courtrooms you could have a real change in behavior, or at least a shift to zero emissions vehicles, which would likely not incur additional coverage from the insurance companies….more data needed!

  8. jeik

    I think the 2nd Ave improvements will really help with downtown pollution levels. Right now, I am frequently stopped behind a car on 4th Ave in the evening, just feeling the heat of the exhaust. Getting out of traffic, and even 10 ft away from it, will reduce pollution quite a bit.

    I’m really glad people are starting to think about this, and that it may actually affect decisions about where and what kind of bike facilities we build. However, the world really needs to transition off of gasoline cars all together in the next 15-20 years, and there’s no reason Seattle shouldn’t be at the forefront of that with our cheap and clean electricity. If city leaders take this public health threat seriously, we should be accelerating the transition to EV’s!

  9. Lori

    “In fact, the worst vehicle pollution is often emitted as the vehicle starts up from a stop.” Are you promoting idling??? That’s how it reads. Voluntary idling (while eating/texting/talking/waiting for people/smoking/reading, etc.) is a rapidly growing problem in Seattle and one that has been taken seriously in other cities/states/countries. An idling vehicle emits 20 times more pollution than one traveling at 30 miles per hour. Each day, by voluntarily car idling, Americans as a whole may be burning as much as 3.8 million gallons of gasoline, which, in turn, results in producing about 40,000 tons of CO2. Annually, the cumulative effect is staggering, as we may be uselessly burning 1.4 billion gallons of gasoline and emitting 13 million tons of carbon dioxide as a result. References for this and other idling info can be found here:
    http://www.thehcf.org/antiidlingprimer.html (Hinkle Charitable Foundation)
    http://www.hcdoes.org/airquality/Anti-Idling/IdleKnow.htm (Hamilton County Environmental Services)
    http://www.helptheair.org/idle-free (Kentuckiana Air Education)
    http://www.southwestohioair.org/ (Southwest Ohio Air Quality Agency)

    1. Packet

      Sure idling. We see it all the time at stop lights and parking lots like I-5 as our leaders have no vision. If I can say one good thing about CA its they have freeways to drive on not park cars on like our permanent multi-idling parking lots of I-5, I-405, I-90, and I-520. Meanwhile where high speed rail could have been built you have bike trails while the slow light rail gets slowly built on a federal budget that has no money compared to the money they wasted to get there.

  10. nullbull

    Kill idling in cars and you kill a lot of this problem. The technology to do this and ONLY this (not a full hybrid, just the end of idling) already exists, is heavily deployed in hybrids and could easily be deployed for all new cars. It would do wonders.

  11. Astrid

    I wonder if the higher pollution levels at the Fremont Bridge and downtown areas are also added to by the motorized boat traffic nearby?

    1. Packet

      Sure some but little. Where as the entire port brings more pollution too you than wood stoves in Seattle. The port where the ships burn the lowest grade of crude oil no one wants called bunker oil sit idling to get unloaded or waiting to dock. The ocean going freighter engines are designed to burn crude oil if they have too. Which makes sense as they go where the oil is and freighters bring it home in the past. However most of the ships and you can look at it bringing your iphone and your ipad and iwhatever to your port are burning bunker oil instead as it is the cheapest and no one else wants it. You can find photos on the web of the trail of smoke the leave behind them in the shipping lanes from there to here. Its not DIESEL they are burning its bunker oil and it builds up in the city particularly when the wind stops in the winter and an inversion occurs.

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