Public Health

Urban Highways and Ultrafine Particulate

By Ryan McGreal
Published April 15, 2009

It's already fairly well-known that living close to a highway is correlated with a higher risk of cardiovascular and respiratory diseases, even after controlling for socioeconomic status (property values go down as you get closer to a highway).

Now scientists are trying to hone in on the culprit, and a likely candidate is ultrafine particulate emissions, very tiny particles emitted in vehicle exhaust that can penetrate deep into the lungs and cross into the bloodstream.

The dangers of coarse particulate have long been well understood (though it seems lawmakers can no longer be bothered to do much about it), but many scientists believe that ultrafine particles are even more harmful, though they are far less regulated.

Researchers suspect the health risk from ultrafine particles is greatest downwind and within 300 feet of busy highways. Farther away, the particles tend to dissipate or collide with other particles to become larger. The particles, each thousands of times smaller in diameter than a human hair, are easy to breathe in, and they readily spread throughout people's circulatory systems and enter their brains. On their surfaces, they can carry toxic chemicals and metals.

Tufts University is conducting a study on ultrafine particulate from Boston's urban highways. Here in Hamilton, the city that just loves urban highways, we would be wise to follow this and pay attention to the results.

Ryan McGreal, the editor of Raise the Hammer, lives in Hamilton with his family and works as a programmer, writer and consultant. Ryan volunteers with Hamilton Light Rail, a citizen group dedicated to bringing light rail transit to Hamilton. Ryan writes a city affairs column in Hamilton Magazine, and several of his articles have been published in the Hamilton Spectator. He also maintains a personal website and has been known to post passing thoughts on Twitter @RyanMcGreal. Recently, he took the plunge and finally joined Facebook.


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By Capitalist (anonymous) | Posted April 16, 2009 at 13:19:57

Ryan, greater particulate concentrations are located in highly dense areas. The type of places that you are trying to turn Hamilton into. Why don't you research that instead of continuing with your nonsensical 50 word essay-rants about highways. WE ALL GET IT ALREADY. YOU AND JASON HATE CARS. Do you not have anything original to add to this site???

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By jason (registered) | Posted April 16, 2009 at 13:33:44

yea, you're right. We should try to be more original with our thoughts and comments on here.....

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By Woody10 (registered) | Posted April 17, 2009 at 08:51:28

Although many of you hate the new Red Hill Valley Parkway, I just thought I'd bring it up one more time. It's a lot better around Centennial now than ever before (well, since cars were invented) and the particulates of all types that were hanging around the much more densely populated Centennial were far worse for the common pedestrian (no pedestrians on the highway, usually) so I will never be swayed. Big cities need big roads whether we like it or not. I await your responses, lol.

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By jason (registered) | Posted April 17, 2009 at 09:04:34

Woody 10. You may be right, but we'll never know. The city refused to put air quality monitoring devices along the new Red Hill highway. They obviously know something that you don't.

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By Ryan (registered) - website | Posted April 17, 2009 at 09:22:21


Cities that invest the most in maximizing lane capacity have the worst air pollution - for the (perhaps) counterintuitive reason that when you invest most of your public infrastructure dollars in road capacity, you encourage a lot more people to drive a lot farther a lot more frequently.

Hamilton's lane capacity has grown faster than its population for some time:

As a predictable result, driving is increasing 3-4 times faster than the rate of population growth.

As a result, air pollution from automobiles is actually increasing. It constitutes more than half the total air pollution in Hamilton, and is the major source of nitrogen oxide emissions.

Hamilton's efforts to reduce air pollution by streamlining our traffic network have had precisely the opposite of the intended effect.

That's not even to mention the serious and well-documented health effects of suburban sedentary living, including driving everywhere instead of walking or cycling; isolation and depression in a built environment without public amenities; the increased risk of heart disease associated with time spent driving; the increased risk of traffic collisions where population density is lower; and so on.


Further to what Jason said, we were promised that the construction of Red Hill would deliver specific benefits. It's incumbent on us to measure that progress and assess whether it actually delivered the promised benefits.

Unfortunately, taking the stance "I will never be swayed" prevents us from being able to learn from experience. Sooner or later, the next highway proposal will be on the agenda, and we need to be able to determine whether it will actually deliver on its promises.

The overall evidence from highway construction is that induced demand sooner or later overwhelms whatever efficiency gains come from a temporary increase in relative lane capacity once buildout around the highway interchanges is extensive enough to add enough new vehicles to fill that capacity.

Since the buildout is automobile-based and hence automobile-dependent, people and businesses who moved there because the highway opened up the land are then stuck driving even when it no longer confers even an artificial efficiency.

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By Frank (registered) | Posted April 17, 2009 at 10:06:51

@ Ryan and Jason, while I agree that the city should demonstrate that the RHCE is doing what it's supposed to with data, I live next to Centennial and I feel the difference both in the air and in the neighbourhood. Every urban center needs it's ring roads, we got them (whether it was done right or not is a useless debate now) and now it's time to get rid of the highways in between. For a purely visual representation of the change, visit the intersection of the northbound off ramp and Barton Street at about 8 in the morning and you'll see the traffic that was once driving down Centennial making it hard for school kids to cross the street queuing there. I love it.

I don't hate cars, I own one, I don't hate highways if they're needed and I feel this one was. Jason comments regulary about the York highway that goes by his house as well as the Main Street highway...I had the Centennial highway and by putting in the RHCE, it's made my community much more liveable.

I know the argument you'll repeat is that when you increase highway space, you increase the amount of driving taking place, and my response is that regardless of the increase, the pedestrian safety and liveabiity in the area is a HUGE improvement and in my perspective (and I'm sure you'll find it the same opinion as the vast majority of residents in the area) it outweighs this negative. I also don't believe that the answer to congestion or liveability issues is to create more highways willy nilly, I believe that it's necessary to give through traffic a place to go before changing the neighbourhoods themselves into places where less driving is necessary.

So regardless of the method, a two pronged approach is necessary, there has to be a place for through traffic to go and better planning and land use and improved transit options have to take be in place in order for the desired effects to be attained. In my opinion doing one without the other is counter productive and doing the latter first is a much more difficult approach.

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By jason (registered) | Posted April 17, 2009 at 11:05:23

Frank, you are certainly in a unique spot along with other residents near you who are actually seeing daily life improve because of Red Hill. Count your blessings. 99% of new freeway construction doesn't benefit anyone, but adds more cars and more pollution to their respective cities. I actually feel good for folks in the NE part of the city who are experiencing a little relief from the massive onslaught of pollution that besets that part of town. Of course, with winners there are also losers - all the folks who live adjacent to the valley know that they lost in this one. The city confirmed their suspicions by refusing to track data and monitor air quality in their neighbourhoods after the freeway opening. In an effort to hide the results, the city has really just confirmed what they've all suspected. And of course, the parade of sprawl projects on the SE mountain/Stoney Creek mountain is really the biggest blight of this whole project. We all knew that it was really about residential sprawl and not 'career jobs' and 'manufacturing/industrial job creation' in that area. Hopefully the odd plant will get built in that area before all the land is filled with townhomes, parking lots and parking lots.

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By Frank (registered) | Posted April 17, 2009 at 11:25:24

Jason, I also hate the sprawl projects in the SE end but that doesn't mean that the RHCE is bad... It means the politicians lied and decided to help out their developer friends (are you really that surprised?).

I just had to drive to the other office and as I was doing so, crossed both areas. I don't know the reason the city isn't doing those studies however simply using this as a confirmation of major problems isn't a logical conclusion. The corridor of the RHCE is much larger than that of Centennial as well. What I mean is that the number of people within say 300 meters of the roadway in each direction is far less than what's on Centennial which is densely populated on both sides by residential areas and shopping centres. Also, from my own experience aside from an hour or less around 530, the concentration of traffic is less on the highway itself. What might be a 15 minute trip top to bottom on Centennial through a densely populated corridor is now about 5 minutes on the RHCE through a wider swath of land. Like you, I'd love to see that data, but I wouldn't be at all surprised if that data simply shows that the pollution is now in a corridor that's less populated than Centennial.

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By jason (registered) | Posted April 17, 2009 at 11:34:10

Perhaps. Like Woody10, you may be right, but we'll never know. The city loves to study all sorts of useless things that result in zero action, yet they choose to not collect data on an issue like this that everyone wants and would have been very useful to future planners and residents.

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By Frank (registered) | Posted April 17, 2009 at 14:57:02

Unfortunately being politicians usually means they have a great afinity to acting without logic. Who knows, we might get it yet. Were there any AQ studies performed on Centennial prior to the construction of the RHCE?

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