Overview: From the perspective of pollution from toxic fine particulate matter (PN2.5), Eastern Ontario’s air quality for the first four months of 2026 remains the worst since 2022. April showed some improvement, our monthly average dipping under the WHO-recommended limit of 5.0 µg/m3 for the first time this year. PM2.5 levels had exceeded that limit in a discouraging 55 of the past 76 months, more than enough to significantly impair the healthspans of those Eastern Ontario residents who choose not to take the precautions suggested in our Self-protection page. As usual, the United States was the overwhelming source of almost all that pollution. Toxic emissions from their chronically-underregulated heavy industry, especially oil refining, were again augmented for much of the month with smoke from between 600 and 1,000 southern wildfires. 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 site 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 site gives practical advice on managing household exposure to health-damaging particulates. Updates are posted daily around 7 am but the satellite view below shows the current Kingston reading at any time of day. If you live elsewhere, just click at your location on the map. For ease of personal decision-making, overall daily risk levels are categorized by severity in the table to the right.
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 critical differences between short- and long-term exposure risks.
Commentary as of Sunday May 24 at 7:15 am
Yesterday’s readings: Kingston’s official PM2.5 readings remained well within the healthy Level-0 range all day yesterday as well as overnight, mostly at 2 and 3 µg/m3.
Forecast for today: Kingston readings will be quite unpredictable today, potentially swinging as low as the upper end of the Level-0 range and as high the middle of the Level-2 range.
Detailed forecast: Environment Canada’s 24-hour Kingston forecast calls for continuing southeasterly winds for the entire period. With the high-altitude Jetstream entirely absent from our region, those local wind directions will determine Eastern Ontario air quality. As you can see from the satellite view, the current southeasterly winds are already bringing us unhealthy Level-2 particulate concentrations.
Personal protective measures: This would be a good day to keep doors and windows closed, ideally coupled with HEPA-grade filtration. I’ll be wearing my N95 mask while outdoors whenever the current reading reaches or exceeds my personal threshold of 15 µg/m3.
Like yesterday, this 6:15 am satellite view of PM2.5 fine particulate flows over North America showed healthier-than-usual air quality over much of the eastern USA but a huge cloud of Level-2 concentrations moving up into the Great Lakes and another approaching Lake Ontario from the southeast. The latter is of particular concern to Eastern Ontario in that it is starting to flow overhead.
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.