Overview: Kingston’s average PM2.5 airborne particulate level for March 2025 was 4.5 µg/m3, slightly under the evidence-based WHO limit of 5.0 µg/m3. We have remained mostly just under that limit for an unusually long five-month period as the result of more northerly airflows than Eastern Ontario normally experiences. Given that Kingston has exceeded the WHO limit in 47 of the past 63 months, that stretch of good luck is unlikely to last much longer. If you haven’t gotten into the habit of taking self-protective measures on days with high readings, you will be risking your health and that of your family. Do you know others who might benefit from more awareness of the reality of our air quality and how they can better protect their health? If so, please share this link: https://kingstonairquality.ca.
by Ron Hartling
The purpose of this page is to raise awareness of the uncomfortable reality that, with respect to fine particulate matter (PM2.5), Kingston air quality is consistently worse than the World Health Organization (WHO) standard. The page gives practical advice on managing household exposure to health-damaging particulates. Updates are posted daily around 7 am. If you live elsewhere in Ontario, click on the “Links” menu item above and read the first entry for guidance on applying this site’s information to your situation. For ease of personal decision-making, overall daily risk levels are categorized by severity in this table.
Note that, while most Canadian and US sources define Risk Level 1 as airborne fine-particulate-matter (PM2.5) concentrations less than 12 micrograms per cubic meter (µg/m3), I employ “Level 0” to differentiate readings within the far more evidence-based, less politically-influenced WHO healthy zone. Click on the Health impacts page for clarification on the differences between short- and long-term exposure risks.
Commentary as of Thursday April 17 at 6:55 am
Current readings: Kingston’s PM2.5 hourly readings yesterday were our healthiest since early January, varying from 0 to 3 µg/m3 for a daily average of just 1.4 µg/m3. That was little more than a third of Tuesday’s 3.8 µg/m3. Overnight readings were a steady 2 µg/m3.
Forecast summary: Kingston readings today should remain within the comparatively healthy Level-0 range but will likely rise to Level-1 values sometime this evening or tomorrow. Further deterioration can be expected over the weekend.
Detailed forecast: Environment Canada’s 24-hour Kingston forecast calls for the current westerly winds to have shifted to full southerly by mid-afternoon, calming this evening and overnight. The Jetstream will be fragmented but mostly westerly. Relatively slow winds will hopefully postpone the arrival over Eastern Ontario of a more polluted airmass for another day or so.
Personal protective measures: No such measures will be necessary today and, hopefully, tomorrow.
This morning’s 5 am AirNow PM2.5 map extract for northeastern North America show that, after a couple of days of exceptionally clean air, a more polluted airmass is moving our way. The coming yellow-shaded clouds of unhealthy Level-2 particulate concentrations are currently crossing the Great Lakes both to our north and south.
Summary of recent readings
This table summarizes and provides context for the most recent three weeks of Kingston PM2.5 airborne fine particulate readings. The key numbers are, of course, the daily averages because that’s what informs us how our recent exposures have contributed to or ameliorated whatever annual exposure to toxic particulates we are comfortable with or accepting of. For those who choose to lower their at-home exposure in order to better protect their and their households’ long-term health, the numbers provide important information on how much effort may be required to stay within their comfort levels.
To facilitate that analysis, the table also computes each day’s risk category (usually a mix of 0’s, 1’s and 2’s), as well as 7- and 28-day running averages and medians. It also reports on the minimum and maximum readings for each day, as well as on the number of hours that day during which Kingston PM2.5 readings may have exceeded either or both the World Health Organization’s recommended maximum and the seriously outdated and therefore misleading US/Canadian equivalent.
The AirNow forecast PM2.5 map for Central and Eastern USA tomorrow predicts that the massive polluted airmass will be covering almost the entire US portion of the region, likely reaching up into Canada around Lake Erie. Eastern Ontario should be in for one more day of relatively clean air before the arrival of the incoming airmass.