What do Canada’s new Ambient Air Quality Standards really mean?

Last Friday, Environment Minister Peter Kent and Heath Minister Leona Aglukkaq announced new Canadian Ambient Air Quality Standards (CAAQS) designed to "improve outdoor air quality for all Canadians." That sounds pretty good, but what's really changing?

The new standards are a replacement for the current 'Canada Wide Standards for Particulate Matter and Ozone', which were signed into effect in 2000 and set the levels of fine particulate matter — soot, ash, dirt, dust, chemicals and metals — and ground-level ozone in the air, that are high enough to cause breathing problems even in people with normal, healthy lungs. These standards are used by various agencies across the country to report on air quality, and are typically what they use to set the level of 'Poor' air quality.

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In 2015, the standards for both fine particulate matter and ozone are set to drop slightly, shifting the level of air quality that is reported in the 'Poor' category downward. This will warn the public of unhealthy air quality at lower levels, and these adjustments should 'trickle down' to the lower categories — Moderate, Good and Very Good — in an effort to keep the public informed about the quality of the air they're breathing even when it's not bad enough to set off an advisory.

Now, the amount the standards are lowered by are fairly small. However, for some time in the field of air quality science, questions have been revolving around the standards and the air quality index levels that are set from them.

What's the difference between Moderate and Poor air quality? Are you okay when the concentration of ozone is at the high-end of the Moderate category, and only in danger when it ticks up into Poor? Also, and more importantly, is there a level when the concentrations of these pollutants are low enough that they aren't a danger to us?

Well, the levels are set based on health studies and even the Moderate category provides some warning about 'sensitive' people and those with heart and lung disease. Also, the different levels and their 'breakpoints' are needed to have a system that can be reported without being hopelessly complicated. However, as for the third question, research has been showing that there really isn't a lower limit to when these pollutants do damage to us. Even low levels have an impact on our lungs over long periods of time.

So, even though the changes to the standards are fairly small, this is still a step in acknowledging and responding to that research. Also, the new annual standard being set for fine particulate matter is a big step for this, since this will track the long-term exposure to these pollutants, which has also become a topic of concern.

Will these new standards be a big enough step? The answer to that will have to wait awhile, unfortunately. Starting in 2015, communities will report their air quality with these new standards, and we will have to see, over time, how the air we're breathing measures up.

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By now, most people are familiar with ground-level ozone as a pollutant. This is the same ozone that naturally occurs in the stratosphere, and protects us from harmful ultraviolet rays from the Sun, but it's just down near the ground where we can breathe it in. Although it does occur naturally near the ground in low concentrations, chemicals found in car exhaust and the smoke from coal-burning power plants can produce a lot more of it than happens through nature, and a lot faster.

That brown haze you see hanging like a blanket over the city in the morning? That's not ground-level ozone. That's the car exhaust hanging there, just waiting for the right amount of sunlight so that it can react with oxygen to make ozone. It's long been known that ozone acts as a lung irritant, but recent research has pointed to ozone triggering an immune response by our bodies, making us hypersensitive to anything else that might be in the air. So, when we add in other air pollutants, especially fine particulate matter — the other major component of smog — the reaction of our hypersensitive immune system to breathing that in can send some of us to the emergency room, and even make it difficult for the healthiest of us to draw a breath.

(Photo courtesy: Peter Power/The Canadian Press)

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