Science and Technology for Canadians

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Summary

Even on the clearest days the air is still heavy with pollution. To get the big picture, Environment Canada scientists look at the smallest particles and their effect on human respiration.

Transcript of Video

Voice Over
Every time you start your car, a dose of toxic pollutants is delivered to the environment. The federal government is trying to reduce some of those pollutants by improving the quality of the gas we use. Beginning in the year 2002, the government wants to lower the amount of sulphur in gasoline... dramatically, a move that should have enormous health benefits. But this couldn't happen without research focusing on vehicle exhaust. Scientists say that in a fight against air pollution, what we don't know is probably hurting us.

Jay Ingram
On those days when a dense, brown blanket lies over the city, it's easy to feel the weight of smog. You can see it... smell it... almost taste it.

But even on the clearest of days, Environment Canada's Dr. Jeffrey Brook knows the air is still heavy with pollution. He can measure it. Gases such as nitrous oxides... Carbon monoxide... sulphur dioxide... and more.

Jeffrey Brook
I believe that the public think of smog as that thing they see... the haze... and that really is this mixture of everything. But it's created... the visual effect is created by particles.

Jay Ingram
To get the big pollution picture... you have to look at the smallest particles. They turn Dr. Brook's white air filters gray. Fine Particles are about 1-one-thousandth of a millimetre in diameter... that's the size of bacteria.

They consist largely of carbon and sulphur material. They can be liquid or solid. Forty percent of them come from vehicles. They're in the exhaust... along with:

Carbon Monoxide
Carbon Dioxide
Sulphur Oxides
Nitrogen Oxides, And something called Volatile Organic Compounds.

Mix them with the Nitrogen Oxides and Sunlight...and you get ground–level ozone.

It's a complex cocktail that comes out of your tailpipe and goes straight down your windpipe.

Jeffrey Brook
The particles may be special, because of the fact that they contain a lot of different chemicals. They're kind of a by-product of many different emissions and also they're very small, and they can come right down into the lung and carry these chemicals with them, without getting perhaps scrubbed out up in the upper respiratory tract.

Jay Ingram
Are they harming us? Researchers think so.

In a series of studies, Brook's measurements of air pollution in Canadian cities have been compared to hospital admission records. The results show a consistent pattern.

Rob Burnett
So when outdoor air pollution is higher, we can see that more people get admitted to hospital for heart and lung problems, compared to days when its very clean.

Jay Ingram
But Burnett's work can only show correlation... trends. He knows what is happening... but he doesn't know why... And he doesn't know how pollutants take their toll on the lungs and the heart.

Rob Burnett
What do we do now? Everyone admits that there's a problem. Where do we go from here? And this is where we need new thinking... new research... new types of science and new types of policy. We want to understand who is being affected by air pollution, We want to understand why they're being affected.

Jay Ingram
In Ottawa, Dr. Renaud Vincent is looking for pieces of that puzzle.

Renaud Vincent
This is a tissue sample of lungs...

Jay Ingram
He's mapping the pathways that inhaled particles follow in the body... not in humans... but in lab rats.

He uses a specially designed machine to expose rats to air that's peppered with fine particles. Researchers can measure the immediate impact on the rat's heart. Later, under the microscope, they'll examine its lungs for signs of damage. The work has yielded two clues.

Renaud Vincent
Surprisingly we found that particles will have an impact on the lungs, but not in a classical way. Particles are not acutely toxic by themselves. In healthy lungs they might not cause a lot of acute injury in the short term... we do not know in the long term, but in the short term they do not adversely affect the structure of the lungs. However, if there is a lesion in the lung, the particles will amplify that lesion.

Jay Ingram
It means that particles can further irritate an existing lung injury... not allowing it to heal. Dr. Vincent believes this could explain why people with respiratory problems, like asthmatics, are more likely to seek medical help on a smoggy day.

Tracing the route particles take to the heart is more difficult. Dr. Vincent has found that particles in the lungs alter the chemical cues that control blood pressure in the cardiac arteries. He suspects the changes in blood pressure could be sufficient to trigger a heart attack, in a patient with an existing cardiac condition.

Work is now underway to take these findings one step further... and try to verify them in humans.

Jay Ingram
At this lab in Toronto, researchers are looking at human response to inhaled pollutants.

Frances Silverman
To do that, we used what we call a controlled environmental facility in which we can have people inhaling controlled levels of say... it's an air pollutant like ozone or particulate matter. We can control the amount that they inhale. They can inhale it under natural conditions.

Jay Ingram
First, researchers record baseline measurements... including a check of the volunteer's lungs and heart.

Then the subject spends several hours inside a sealed capsule. They breathe filtered air and a mixture of pollutants drawn directly from outside. Researchers keep the concentration consistent and they can simulate everything from a clear day in Toronto to a smoggy day in Los Angeles. But at no time is the subject ever exposed to levels they wouldn't realistically face outside the lab.

Frances Silverman
We want the information from the real life level, not from something that's so high that there's no relevance to what people are actually exposed to.

Jay Ingram
After the test, researchers check the subjects' lung and heart performance... and look for any signs of irritation in the nose, throat and lungs.

As yet, there are no results available. Work started first with healthy subjects. Tests are now looking at mild asthmatics.

Dr. Silverman says in the end, testing the response to individual pollutants won't be enough.

Frances Silverman
What we postulate is, in this case, that where we're really going to begin to see responses at low levels is when you have mixtures of particulates and gases. So, I think that... this is a long laborious process, but as we go along we get more and more information in order to be able to say "hey, listen... If we're seeing this effect, maybe we should be controlling it to this level, at least now."

Jay Ingram
Among its initiatives, the federal government is trying to control air pollution by controlling the quality of gasoline that goes into your car engine in the first place.

Over the next six years, the government plans to reduce the level of sulphur in gas by up to 90 percent.

It claims that will bring down the levels of many pollutants... including particles.

For example, in the city of Toronto, that would mean a drop of five to 10 percent in sulphate particles.

That may not seem like much, but an international panel of experts has advised the government, the impact Canada-wide over 20 years will be enormous.

Ross White
... and over that time about 2,100 premature mortalities would be avoided. And, for example, 93,000 cases of childhood bronchitis would be avoided and 11-million, over that period, of acute respiratory symptoms... for instance croup and coughs... So that's the kind of benefit that would be achieved through the lowering of sulphur in gasoline.

Jay Ingram
And if that's the result of a small drop in particles, scientists studying air pollution say they can only imagine what a larger drop could achieve.