The Big Picture
by Ron Hartling
The fact of the matter, however uncomfortable it may be for us to accept, is that Kingston air quality is nowhere near as healthy as most of us have long believed. The hard line in the sand is the WHO-recommended limit of 5 µg/m3 annual exposure to airborne fine particulate matter (PM2.5). As described in our Health Impacts page, excess mortality is negligible for exposures under that limit but begin climbing exponentially after just 5.8 µg/m3. While there’s absolutely nothing that can be realistically be done by ourselves or our governments to improve the quality of Kingston’s ambient air, we have the choice of either taking reasonable steps to reduce our personal exposures or, by default, simply accept a reduced healthy lifespan.
As documented in our Evidence page, very little of the damaging particulates are emitted locally. The bulk of what we breathe comes from two quite different distant sources, Canadian wildfires and US industrial emissions. The net effect at any point in time is the sum of the sum of the particulates reaching our area at that time.
Canadian Wildfire Smoke
Most of the wildfire smoke reaching Eastern Ontario is emitted from burning Canadian forests. The root cause is climate change; ever-rising temperatures caused by excess carbon emissions that the world’s governments can’t bring themselves to curb, regardless of consequences. That excess atmospheric heat changes wind and precipitation patterns, making rainfall more sporadic and thereby allowing forest biomes to dry out to the point that fires are more likely, cover ever-larger areas, lasting longer and being harder to control.
Proximity matters in that, on average, Eastern Ontario airborne particulate concentrations are significantly higher for nearby wildfires than distant ones. The chances of any given wind pattern bringing highly-concentrated particulates to our area from fires burning in Ontario and Québec are much higher than those in Western Canada. That’s why the 2023 wildfire season brought us our worst-ever PM2.5 readings while the summer 2025 season is not quite so bad even through the fires are more widespread.
Despite the 2023 severity and the obvious fact that the trend can only worsen, governments took no effective measure to reduce the risks, either by substantially reducing carbon emissions or improving Canada’s wildfire control capabilities. Click here to view an obvious Canadian solution.
US industrial emissions
While wildfire smoke seriously contributes to our average annual PM2.5 exposure, it is at least somewhat obvious and mostly occurs in the April to August timeframe with the most damaging fires typically burning in June and July. While less intense, the majority of the particulates in our lungs come from US heavy industry. See our Evidence page for substantiation of that assertion. A rough analysis of average Kingston PM2.5 levels in the non-wildfire months suggests that wildfire smoke constitutes only 13% of our annual exposure. The year-round majority goes essentially unnoticed.
Without sophisticated and expensive chemical analysis of both the airborne particulates themselves and the emissions from each and every industrial facility in the continent (which will never happen) it is almost impossible to identify the sources of the pollutants which we breathe. That said, my daily observations of the past year have convinced me that much if not most of the airborne particulates reaching Eastern Ontario originate in what I have termed the “Texas/Louisiana refinery belt”. That is where most of this continent’s oil refineries happen to be located.
More specifically, what I’ve noticed from the US AirNow PM2.5 maps which I post daily is a roughly weekly “particulate cycle” whereby the yellow-shaded areas with unhealthy Level-2 concentrations of airborne particulates build up near their points of origin, are driven by prevailing southwesterly winds across eastern North America and then exit over the Atlantic. Some weeks, when we’re lucky, the winds don’t push them as far north as Eastern Ontario. Other weeks, they bring us bad-air days. The four 2025 screenshots below were chosen as representative of the main phases of that cycle: [1] relatively clean air as a result of southerly winds along the Gulf Coast; [2] a particulate buildup over the southern States; [3] continued expansion of the particulate cloud as it moves northeast; [4] the particulates beginning to be flushed out over the Atlantic, sometimes enveloping Eastern Ontario and sometimes not. The actual weekly reality is more variable depending on the mix of wind directions on any given day.
While it is true that the vast majority of the particulates which we breathe in any given year originate from US sources, it would be unfair for American business interests to bear the full blame (in the unlikely event that they cared) because much of the crude oil which Canada exports is sent to those refineries for processing. We are therefore getting back a significant portion of the pollutants which we profit from exporting.
