by Ron Hartling

From many different conversations, I’ve learned that most Kingstonian believe that the air we breath must be quite healthy air as a result of our living in a non-industrial city which is both reasonably environmentally conscious and far distant from most polluting industries. The charts below indicate that Kingston air quality is in fact better than most other Ontario cities but prove that it is far from healthy given that we consistently exceed evidence-based WHO PM2.5 recommendations.

For Ontario at least, 2022 was one of the best years in the past two decades from an air quality perspective. The above table confirms that Kingston’s air quality was in fact healthier than most other Ontario cities. Yet, even in 2022, our average PM2.5 concentration still exceeded the WHO’s 5.0 µg/m3 maximum.  WHO recommendations also specify that daily averages must not exceed 15 µg/m3 more than 3 or 4 times annually. Kingston’s 2023 air quality was the worst in recent memory, our 8.7 µg/m3 annual average being 173% of the WHO recommended maximum.  We also exceeded the 15 µg/m3 limit on 32 different days!  Looking back in the 18-year table to the right, Ontario air quality improved rapidly after 2011 due to the McGuinty government’s closing of all coal-fired power plants, but the dire changes being brought about by runaway global heating have now more than reversed those gains, rendering our air quality worse than ever.

The following charts conclusively refute the assumption that most of Kingston’s air pollution stems from local and regional emissions. Were that hypothesis to be true, our PM2.5 readings would vary dramatically by time of day and would improve significantly on weekends. In reality, there are few signs of the overnight and weekend drop in emissions from local businesses and households having more than a marginal impact in our air quality.

The table to the right shows that average PM2.5 concentrations vary with time of day by less than 10% and actually tend to be lower during prime working hours. The above table shows some significant seasonality, but which is mostly unrelated to local activities.  It’s not surprising that PM2.5 levels are modestly higher during winter months given that northern North American residential heating is still mostly fossil-fueled. The major variation for Kingston is from June, July and August, which are the peak months of the Canadian wildfire season.

So, if Kingston’s bad air isn’t due to local emissions, where are those toxic pollutants actually coming from? Given our location, the candidates are Western Ontario, Quebec and the USA.  Fortunately, Environment Canada makes historic Kingston hourly wind readings available for download.  The 2022 daily averages are summarized in the table to the right, which makes it eminently clear that, apart from the occasional peaks during wildfire season, the USA is the prime cause of Kingston’s frequent bad air days. Moreover, the lack of time-of-day variability as discussed above points to airborne pollutants from heavy industrial plants, which typically operate on a 24/7 basis, as being the principal culprits.

The bad news, therefore, is that there is little that our City and its residents (and indeed, every level of Canadian government) can do to influence the quality of the air that’s coming our way.  This correlation between Kingston hourly PM2.5 reading with wind directions makes it crystal clear that, apart from occasional wildfires to the north of us, our air quality quickly improves when winds shift to northerly and just as quickly deteriorates when they turn southerly. All we can do to protect ourselves is to better manage our indoor air quality on bad-air days.