The World Health Organization has called air pollution the world's greatest environmental health risk. An editorial just published in the Canadian Medical Association Journal is calling on Canada to adopt WHO guidelines to help clean up the air we breathe.

The editorial calls on Canada to adopt and enforce the WHO guidelines on air quality standards. The Canadian standard for the peak daily concentration of air particles of less than 2.5 micrometers in diameter is 28 micrograms per cubic meter; the WHO guideline is lower - at 25 micrograms per cubic meter. The editorial says the WHO guidelines should be adopted and enforced at the federal and provincial-territorial level. It says best practices for reducing pollution should be shared across jurisdictions, and that enforcement and practices should take into account local sources of pollution.

Behind the editorial's call are some alarming health statistics. The WHO says pollution is linked to one in eight deaths worldwide. In 2008, doctors estimated more than 20,000 Canadians per year died prematurely due in part to outdoor air pollution. Air pollution has both short and long term effects on humans. Higher concentrations of pollutants have been associated with increased admissions to hospital for respiratory diseases like asthma and chronic obstructive pulmonary disease and for heart disease. This may surprise you, but air pollution has also been linked to an increased risk of Alzheimer's disease.

Children are especially vulnerable to air pollution. A large population study of kids who live in southern California found that increased concentrations of nitrogen dioxide and other air pollutants had affected the development of their lungs. That is a precursor to lung and heart disease later in life. Just to show you that this is cause and effect and not an associated finding, air pollution levels in California have been going down. Two thousand California kids had their lung function measured; as levels of nitrogen dioxide in the atmosphere went down, lung function in this kids improved.

There are many sources of air pollution that are man made. The contributions from the oil and gas industry are well known. Wood burning stoves also add to air pollution. Diesel powered vehicles contribute more than half of all nitrogen dioxide emissions in Canada. Diesel powered buses increase the risk to kids. Around 10 million Canadians live near major highways and intersections that expose them to pollution related to traffic. Schools that are situated close to major traffic centres increase the risk further still.

Despite the health statistics, I think it's unlikely we'll see major cuts in air pollution in the near future. With so much of our economic output depending on oil and gas, there's a tendency in Canada to see a win on air pollution as a loss for the economy. Another factor often cited as a barrier to progress are overlapping jurisdictions and responsibilities of cities, the provinces and the federal government. It's hard to build a broad consensus that gets everyone moving in the same direction.

That said, the editorial in CMAJ makes the point that while Canada lags behind, Beijing and Paris (both pictured on this blog) have made progress - proving that it can be done. In the meantime, the editorial urges us to consider the things we do as individuals that harm air quality - and act accordingly.