For years, the big indicator used for measuring pollution from traffic in cities was Nitrogen dioxide, NO2. However ultra-fine particles are now being looked at as a serious issue. A new study has looked at their distribution in the City of Toronto. The authors write:
Traffic-related air pollution is known to contribute to cardiovascular morbidity including both acute and chronic health effects. To date, population-based studies interested in the potential health effects of traffic-related air pollution have generally relied on NO2 as a surrogate measure of exposure owing to the availability of existing land use regression models. However, other air pollutants such as ultrafine particles (UFPs) (<0.1 um) may also contribute to adverse health effects. In particular, a number of studies have examined the acute health effects of UFPs and existing evidence suggests that these pollutants may contribute to acute changes in vascular function and cardiac autonomic modulation.
One of the study's authors, Marianne Hatzopoulou, points out how dangerous this is for cyclists in particular. Luke Simcoe writes in Metro News:
Her work shows cyclists are particularly vulnerable to the risks posed by air pollution — higher levels of breast and prostate cancer being among them. Cyclists, she said, “tend to have higher breathing rates than other pedestrians, so whatever they’re inhaling is going deeper into their lungs.” It’s a reminder that encouraging healthy urban environments means more than adding cycle tracks and bike lanes, said Hatzopoulou, a civil engineering professor.
Using data from the study, she and her team have developed the Clean Ride Mapper, which lets cyclists pick the route with the cleanest air.
It is based upon a computer algorithm and modelled traffic and air quality data. The routes proposed should therefore be understood as a best-guess effort. Users are urged to exercise judgment regarding the safety of specific suggested routes and to independently verify route information presented here. This route planning service is provided as is with no guarantee of any kind.
That is an appropriate disclaimer; I applied the tool to the route from my home to Ryerson University where I teach. I used to take the route that it shows in blue as shortest; I now take a different one that keeps me in bike lanes all the way. However the cleanest route is truly a mess, full of twists and turns through residential areas. It also has me going the wrong way on one way streets. But it is a good indicator. Another level of data, shown as dots, are the spots where there were bike crashes and injuries. Hatzopoulou notes:
We’re encouraging densification and also encouraging all modes of active transportation, but we’ve done nothing to reduce the number of cars on the road,” she said. “So all we’re doing is putting cyclists and pedestrians closer to the pollution.
These data are for Toronto, but this is a problem everywhere. In the Guardian, Susana Rustin writes about pollution, mostly from cars:
It also causes people to die from heart attacks, strokes and lung cancer, and exacerbates other lung diseases and asthma. Usually it’s not the only cause, but air pollution is a factor in at least 30,000 deaths each year in the UK, although scientists are struggling to disentangle the damage caused by nitrogen dioxide from that caused by particulates, or soot. By way of comparison, in the UK there are up to 100,000 smoking-related deaths each year, nearly 9,000 alcohol-related ones and about 1,800 people killed in car crashes.
Surely it's time to think about this and do something other than building more highways.