What would happen if a group of chain-smokers were left in a closed room for a night with a carton of cigarettes? They may, the next day, suffer from headaches, nausea and/or some coughing.
But what would happen if a small car were left running in that same room? Everyone would be dead after a few hours.
This analogy is particularly relevant when one considers that every day, 24 hours a day, tens of thousands of cars and trucks are releasing their exhaust on the streets of our cities. Urban air pollution can reach harmful and even lethal levels and the coming cooler temperatures won't save you.
In fact, some of the deadlier airborne chemicals we're breathing, like carbon monoxide, are more prevalent in winter months.
Thanks to regulations, nowadays one need not be exposed to cigarette smoke unless one chooses to. But for those living in the city, no such choice exists when it comes to avoiding car exhaust.
It's not easy to quantify the amount of air pollution we're exposed to daily, but we set out to determine it by measuring carbon monoxide and volatile organic compound levels the airborne chemicals most responsible for respiratory-related illness and death at various intersections throughout the city, beginning in Kensington Market, for comparative purposes, on a Pedestrian Sunday in late August when there's no vehicular traffic (see data in Insight).
The levels we measured were for the most part too low to have a measurable short-term effect on individual health. Taken together, however, all the poisonous compounds in the air constitute a deadly cocktail.
Chemical compounds in the air put a constant stress on our ability to process toxins. Certain chemicals cannot be processed by our body and thus accumulate in our tissues. Carbon monoxide, for example, permanently takes the place of oxygen in red blood cells.
Driving or walking in or near traffic is the equivalent of taking a puff of a concentrated toxic mixture. One of our colleague's blowing cigarette smoke directly into the air quality meter produced a carbon monoxide spike comparable to that of a car passing two metres away.
In order to visualize the mid- to long-term potential of environmental pollution, consider that except for our brain cells, all the cells in our bodies will be replaced within seven years.
The material our bodies use to constantly regenerate our biological structure is whatever we eat, drink or breathe. Whatever pollutants are present in these building materials are either disposed of by our bodies or get incorporated and accumulate.
We've known for decades about the adverse environmental impacts of vehicle emissions, and with each summer heat wave we're feeling the effects of pollution even more acutely.
Contrary to popular belief, colder temperatures do not provide a reprieve. Nitrogen dioxide, sulphur dioxide and carbon monoxide which together account for 80 per cent of pollution-related premature deaths are actually present at higher levels in colder months.
It's increasingly urgent to take steps to promote a renewed vision for the city and its transportation system.
Jean-François Gouin is an executive member of the Institute for Research and Innovation in Sustainability at York University. Satoshi Irei is with the Centre for Atmospheric Chemistry at York.