Overview: From the perspective of pollution from toxic fine particulate matter (PN2.5), Eastern Ontario’s air quality for the first quarter of 2026 remains the worst of the past seven years. March showed some improvement, but remained the third worst since 2020. PM2.5 levels have now exceeded the 5.0 µg/m3 WHO limit in a discouraging 55 of the past 75 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. Once again, the United States remains the overwhelming source of almost all that pollution. Thus far this year, their usual unconscionably-underregulated heavy industry and especially oil refinery emissions have been augmented by smoke from between 600 and 1,000 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 Wednesday April 22 at 6:40 am
Yesterday’s readings: As predicted, Kingston’s official PM2.5 readings yesterday remained mostly at comparatively healthy Level-0 values between 3 and 5 µg/m3, though there were a pair of anomalously high early-morning readings which weren’t reflected in the satellite view so may be attributed to some rare smoke emissions near our sensor station. Our daily average was 4.6 µg/m3, roughly 50% higher than Monday’s 2.9. Overnight readings climbed from 4 to 6 µg/m3 but the satellite view showed us at having jumped up to a Level-2 15 µg/m3 by 6:30 am.
Forecast for today: Today’s Kingston PM2.5 readings will likely vary between the upper end of the moderately-unhealthy Level-1 range and the lower half of Level-2.
Detailed forecast: Environment Canada’s 24-hour Kingston forecast calls for the current calm air to become full southerly winds by mid-morning, turning southwesterly this afternoon and then full northerly overnight. That is consistent with the high-altitude Jetstream being absent over Eastern Ontario for most of today but becoming strongly northwesterly sometime this evening. The satellite view paints a grim picture of toxic US pollutants in all those directions, inflicting upon us an unwelcome and unhealthy bad-air day.
Personal protective measures: I would recommend keeping windows and doors closed today if at all possible, and checking back on this page before undertaking outdoor activities. I’ll be donning my N95 mask for outdoor use whenever the current reading is 15 µg/m3 or higher.
As of 6:15 am, this satellite view of PM2.5 fine particulate flows over North America showed continued southwesterly airflow concentrating southern US industrial emissions and wildfire smoke over the eastern Great Lakes, continuing up to northern Ontario and most of populated Québec. region and concentrating them there. The GTA is currently suffering from the worst of that pollutant-concentrating airflow with very toxic Level-3 readings. Eastern Ontario is receiving a still-quite-unhealthy Level-2 airflow from the New England region.
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.