Media Releases

Traffic emissions may pollute 1 in 3 Canadian homes

April 21, 2015

Engineering studies find harmful vehicle emissions spread farther than thought, with variable pollution levels across cities

A trio of recent­ly pub­lished stud­ies from a team of Uni­ver­si­ty of Toron­to engi­neers has found that air pol­lu­tion could be spread­ing up to three times far­ther than thought – con­tribut­ing to vary­ing lev­els of air qual­i­ty across cities.

Past research on air pol­lu­tion from vehi­cle tailpipes has shown poor air qual­i­ty any­where between 100 to 250 metres of major road­ways.

But in a paper pub­lished in the recent edi­tion of the jour­nal Atmos­pher­ic Pol­lu­tion Research, U of T chem­i­cal engi­neer Greg Evans (ChemE) and his part­ners at Envi­ron­ment Cana­da have found that con­cen­tra­tions of pol­lu­tants from traf­fic are still dou­ble at a dis­tance of 280 metres down­wind from high­way 400 north of Toron­to.

One in three Cana­di­ans, and half of all Toron­to­ni­ans, lives with­in 250 metres of at least one major road­way. These roads, says Evans, range from 10-lane high­ways to most four-lane streets with steady traf­fic.

“We used to think that liv­ing near a major road meant that you lived near a lot of air pol­lu­tion,” says Evans. “But what we’re find­ing is that it’s not that sim­ple, some­one liv­ing right on a major road in the sub­urbs may not be exposed to as much pol­lu­tion as some­one liv­ing down­town on a side street near many major roads.”

In the same study, Evans demon­strat­ed that for some­body liv­ing near mul­ti­ple roads, they could be exposed to up to ten times more pol­lu­tants than if they didn’t live near any major roads.

“It used to be that we mea­sured air qual­i­ty on a region­al or city scale,” says Evans. “But now we’re start­ing to under­stand that we need to mea­sure air qual­i­ty on a more micro scale, espe­cial­ly around major road­ways.”

Accord­ing to Health Cana­da, poor air qual­i­ty from traf­fic pol­lu­tion is asso­ci­at­ed with a num­ber of health issues, such as asth­ma in chil­dren and oth­er res­pi­ra­to­ry dis­eases, heart dis­ease, can­cer and increased rates of pre­ma­ture death in adults. The Cana­di­an Med­ical Asso­ci­a­tion attrib­ut­es 21,000 pre­ma­ture deaths each year in Cana­da to air pol­lu­tion. A sep­a­rate study pub­lished last month also linked traf­fic pol­lu­tion to delayed cog­ni­tive devel­op­ment in chil­dren.

Lab in a truck

Through­out 2014, the research team trav­elled the streets of Toron­to mea­sur­ing vehi­cle emis­sions from a mobile lab that resem­bles a Cana­da Post mail truck.

“One of the aspects of our work that’s unique is that we’re using real-time instru­ments to make mea­sure­ments in sec­onds,” says Evans. “You have to do the mea­sure­ments right there, right away, or the exhaust will be gone.”

The team’s find­ings sug­gest that peo­ple liv­ing or spend­ing time near major road­ways could be exposed to ele­vat­ed lev­els of a dan­ger­ous chem­i­cal brew of ultra­fine par­ti­cles, volatile organ­ic com­pounds, black car­bon and oth­er pol­lu­tants.

“The ultra­fine par­ti­cles are par­tic­u­lar­ly trou­bling,” says Evans. “Because they are over 1,000 times small­er than the width of a human hair, they have a greater abil­i­ty to pen­e­trate deep­er with­in the lung and trav­el in the body.”

On a typ­i­cal sum­mer day in Toron­to, Evans’ instru­ments mea­sure approx­i­mate­ly 20,000 ultra­fine par­ti­cles in each cubic cen­time­tre of air. This means that for every aver­age breath, Toron­to­ni­ans are inhal­ing 10 mil­lion of these nano-sized par­ti­cles. These num­bers increas­es to 30,000 and 15 mil­lion in the win­ter, when there is more stag­nant air and less evap­o­ra­tion of the com­pounds.

25% of cars caus­ing 90% of pol­lu­tion

A sec­ond paper by Evans and col­leagues, pub­lished in the March 2015 edi­tion of the jour­nal Atmos­pher­ic Mea­sure­ment Tech­niques, sug­gests that a small num­ber of old­er or “bad­ly-tuned” cars and trucks pro­duce the major­i­ty of vehi­cle pol­lu­tion.

The study made on-the-spot mea­sure­ments of 100,000 vehi­cles as they drove past air-sam­pling probes of the main lab­o­ra­to­ry on Col­lege Street, one of Toronto’s many major road­ways.

Evans and team found that one-quar­ter of the vehi­cles on the road pro­duced:

  • 95% of black car­bon (or “soot”),
  • 93% of car­bon monox­ide, and
  • 76% of volatile organ­ic com­pounds such as ben­zene, toluene, eth­yl­ben­zene and xylenes, some of which are known-car­cino­gens

“The most sur­pris­ing thing we found was how broad the range of emis­sions was,” says Evans. “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.”

A vehi­cle emis­sions map of Toron­to

A third paper, due out in the June 2015 edi­tion of the jour­nal Atmos­pher­ic Envi­ron­ment, looks at vari­a­tions in traf­fic pol­lu­tion through­out Toron­to, eval­u­at­ing how expo­sure to large­ly unex­plored, unreg­u­lat­ed ultra­fine par­ti­cles varies across the city. View map here.

Evans is cur­rent­ly work­ing with Envi­ron­ment Cana­da, the Ontario Min­istry of the Envi­ron­ment and Cli­mate Change and Metro Van­cou­ver to design, test and install new air qual­i­ty mea­sure­ment sta­tions around the cities of Toron­to and Van­cou­ver. These sta­tions will sup­port enhanced mon­i­tor­ing of the air qual­i­ty health index dur­ing this summer’s Pan Am games in Toron­to. More broad­ly, this research will pro­vide a basis for future near road air qual­i­ty mon­i­tor­ing in cities across Cana­da so as to get a more accu­rate por­tray­al of the expo­sure of Cana­di­ans to traf­fic pol­lu­tion.

Evans and team hope that their research may some­day lead to pol­i­cy changes that could help bet­ter tar­get the small num­ber of vehi­cles that pol­lute the most, as well as to bet­ter decide where to build schools, hos­pi­tals, day­cares, seniors res­i­dences and oth­er struc­tures to pro­tect peo­ple who are espe­cial­ly vul­ner­a­ble to air pol­lu­tion.


For more infor­ma­tion:
RJ Tay­lor
Media Rela­tions Strate­gist
Fac­ul­ty of Applied Sci­ence & Engi­neer­ing