Very long way to go to meet new WHO air guidelines

A few weeks ago, the World Health Organization (WHO) announced new, stronger guidelines for air pollutants.

WHO warns that “exceeding the new air quality guideline levels is associated with significant risks to health” and notes that “adhering to them could save millions of lives.”

The new guidelines for fine particulate matter (PM2.5) – which wood smoke is full of – are notably tougher than Canada’s Ambient Air Standards and BC’s Air Quality Objectives.

And, in the winters in the Comox Valley, we frequently exceed the new WHO guidelines, meaning we face “significant risks to health.”

The new WHO guidelines reflect the growing awareness and understanding of the health risks associated with exposure to even low levels of PM2.5.

“Since WHO’s last 2005 global update, there has been a marked increase of evidence that shows how air pollution affects different aspects of health. For that reason, and after a systematic review of the accumulated evidence, WHO has adjusted almost all the [Air Quality Guidelines] levels downwards….”  (WHO News Release, Sept. 22, 2021)

How do we measure up?

There are usually two measurements reported for PM2.5. One is the annual average (the average of how much PM2.5 there is over a full year). The other is the average for a 24-hour period. Both are measured in micrograms per cubic metre (ug/m3).

National and provincial comparison

This table highlights the differences in WHO, Canada and BC’s benchmarks for PM2.5, in ug/m3:

Local air quality measurements

In the last report for the Georgia Strait Air Zone (2017-19), there were two years of data available for Courtenay. Of the 13 communities that have monitors in this Air Zone, Courtenay was once again one of the worst, even after removing smoke from any Transboundary Flow or Extreme Events (TF/EE) such as wildfires.

While we just squeaked under the standards for Canada at the time (until 2020, it was 28 ug/m3 for a 24-hour period instead of 27), we did not meet BC’s Air Quality Objectives. And we didn’t come anywhere near meeting WHO’s new guidelines.

Why we should apply new WHO guidelines

As highlighted by the above table, reports on air zones in Canada all apply Canadian Air Quality Standards (CAAQs) to show how well an area with a monitor is, or isn’t, doing.

In this report, none of the communities are in the ‘red’ (i.e. they didn’t exceed the CAAQs for those years). This is the first report in seven that Courtenay has not exceeded the federal standard for the 24-hour average for PM2.5.

While this might seem like progress, if this report had applied the 2020 Canadian standards, Courtenay would have been in the red.

And if we applied the WHO guidelines, a large majority of the communities would be in red for one or both of the measurements.

As WHO guidelines better reflect how PM2.5 impacts our health, these are the numbers we should now use to assess how well we are actually doing, at least until Canada and BC update their standards and objectives. These numbers should also guide any planning goals and strategies for how we clean up our air.

Additionally, it would change how air quality advisories are issued. These advisories are now called after we exceed the BC 24-hour objective of 25 ug/m3, and are expected to do the same for another day or more.

If we used WHO guidelines to determine when we would have air quality advisories, we would have quite a few more advisories in the winter which would better reflect how much our health is being impacted.

Which type of measurement is better – annual or 24-hour?

When it comes to wood smoke pollution, the more important measurement is the 24-hour average. Even then, as most wood smoke happens at night, averaging it out over a whole day downplays how smoky things are in the evening.

But the annual average is even worse for downplaying the amount of winter wood smoke. Over the summer months, our air is usually quite clean, with an average well below 5. But in the winter months, the wood smoke from heating and burning is far higher. By blending summer and winter, it makes it seem like our air is much cleaner than it is many months of the year.

A better reflection of real time air quality conditions is the current reading for the Air Quality Health Index as it is based on the average PM2.5 of the past hour. (Keep in mind the AQHI number for the Comox Valley is based on the reading at one monitor at Courtenay Elementary School). There are many nights we hit a ‘high’ health risk, yet our daily average ends up being well below 25 ug/m3.

But this real time health risk number is something few are aware of, unless they are familiar with the issues. So people continue to burn away while others open their windows or walk in their neighbourhoods, unaware of the risk they are exposing themselves to.




Posted in Advisories, Health, Monitoring, Problem.

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