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 Saturday April 18 at 6:25 am
Yesterday’s readings: Kingston PM2.5 readings during yesterday’s daylight hours were much healthier than expected, ranging from a near-perfect 1 µg/m3 in the early morning to 3 µg/m3 in the early evening. They then rose, peaking at 8 µg/m3 (Level 1) by 10 pm before fluctuating between 1 and 4 µg/m3 overnight. Our daily average was 3.2 µg/m3, well down from Thursday’s 5.5.
Forecast for today: At the time of writing, Kingston’s PM2.5 readings had already shot up 14 µg/m3, the beginning of the quite-unhealthy Level-2 range. They will likely vary between Level-1 and Level-2 values for much of the rest of the day.
Detailed forecast: Environment Canada’s 24-hour Kingston forecast calls for our current southeasterly winds to shift to full southerly around noon, then southwesterly this evening and northwesterly overnight. Given the continued absence of the high-altitude Jetstream from the eastern Great Lakes, those more local wind directions will determine Eastern Ontario air quality. As you can see from the satellite view, we currently have Level-1 and Level-2 polluted airmasses in all of those directions, which precludes accurate air quality prediction.
Personal protective measures: Despite the warming temperatures, it would be wise to check the current reading on this page before opening windows. I will be checking before outdoor activities and will don my N95 mask whenever they cross the 15 µg/m3 mark.
As of 6:15 am, this satellite view of PM2.5 fine particulate flows over North America shows significantly worsening air quality over the eastern portions of the continent, with toxic southern US industrial emissions and wildfire smoke being pushed all the way up to James Bay. Eastern Ontario is currently enveloped by that polluted airmass.
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.