It’s no secret that “clunkers” on the road contribute to greenhouse gas emissions at an alarming rate. A new study from the University of Toronto confirms what ecologists have theorized for some time: just 25 percent of cars and trucks are responsible for causing 90 percent of the air pollution we breathe. Scientists measured the emissions from vehicles in action to find out exactly how their dirty emissions impact our environment, and some of their conclusions were quite surprising.


air pollution in toronto

The findings, published in the journal Atmospheric Measurement Techniques, illustrate the process researchers used to determine this new information. The scientists recorded emissions from 100,000 vehicles on the road, using air-sampling probes to measure the output on one of Toronto’s busiest roads, College Street. Essentially, the bottom 25 percent of vehicles, the worst offenders in terms of emissions, were found to be the source of 95 percent of black carbon, 93 percent of carbon monoxide, and 76 percent of volatile organic compounds, many of which are linked to cancer.

Related: Air pollution causes more human deaths than other environmental causes

These figures are alarming, and might make you want to run out and buy a cleaner car. To add to the intrigue, researchers also found that how people drive is nearly as important as what they are driving. One of the study’s authors is Greg Evans, a University of Toronto chemical engineer. Evans explains the impact of driving habits on emissions: “As we looked at the exhaust coming out of individual vehicles, we saw so many variations. How you drive, hard acceleration, age of the vehicle, how the car is maintained–these are things we can influence that can all have an effect on pollution.”

The study, conducted in partnership with Environment Canada, calls for better emissions testing, incentives to encourage people to switch to cleaner vehicles (like Cash for Clunkers programs), and an increased importance placed on conservative driving habits. The team is confident that a combination of these strategies would make an enormous impact on reducing greenhouse gas emissions and improving the health of our world.

Via Treehugger

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