SmogRank / Episodes / Canada

Ontario and Quebec, Canada, July 2026

For 1 day, on 12 July 2026, 8 cities in Canada had PM2.5 at least twice their usual for the time of year. The worst reading was Nepean, Ontario, Canada: 41.9 µg/m³ on 12 July, about 2.9× its usual 14.3. Ended 12 July.

Few fires were detected near these cities on those days. Spreads like this usually come from still weather trapping smoke from heating, traffic and industry, or from dust.
Cities reached8in 1 country
Days112 July 2026
Worst day12 July8 cities counted
Furthest above usual5.8×Gatineau

Day by day

12 July 8 cities at twice their usual or more
RochesterNewmarketTorontoAllistonSt. CatharinesMississaugaBuffaloNorth BayBramptonOakvilleMiltonSyracuseWaterdownHamiltonGuelphBrantfordKitchenerCornwallUticaGreater SudburyLondonSt. ThomasMontréalRivière-des-Prairies–Pointe-aux-TremblesBrossardSaint-Jean-sur-RichelieuAlbanySarniaSorel-TracyPort HuronChathamRutlandBenningtonGranbyPittsfieldNorth AdamsNew BaltimoreShawiniganDrummondvilleTrois-RivièresEastpointeBécancourHartfordGreenfieldRoyal OakSouthfieldKeeneRedfordBarrieNepeanParry SoundKingstonOttawaBellevillePeterboroughGatineau
9 Jul101112131415
Every measured city in the area, coloured by its PM2.5 that day; a dark ring marks a city at twice its usual or more. Bars: cities counted each day, coloured by their median level. Choose a day or press play; without JavaScript, the days link to that day's world ranking.

How it spread

NepeanNepean, 9 July: 16.3 µg/m³Nepean, 10 July: 27.7 µg/m³Nepean, 11 July: 31.6 µg/m³Nepean, 12 July: 41.9 µg/m³, 2.9× its usual 14.3Nepean, 13 July: 30.0 µg/m³Nepean, 14 July: 39.9 µg/m³Nepean, 15 July: 28.5 µg/m³GatineauGatineau, 9 July: 12.6 µg/m³Gatineau, 10 July: 21.9 µg/m³Gatineau, 11 July: 30.8 µg/m³Gatineau, 12 July: 36.6 µg/m³, 5.8× its usual 6.3Gatineau, 13 July: 26.6 µg/m³Gatineau, 14 July: 32.7 µg/m³Gatineau, 15 July: 20.5 µg/m³PeterboroughPeterborough, 9 July: 4.5 µg/m³Peterborough, 10 July: 6.8 µg/m³Peterborough, 11 July: 18.0 µg/m³Peterborough, 12 July: 31.8 µg/m³, 4.2× its usual 7.5Peterborough, 13 July: 14.5 µg/m³Peterborough, 14 July: 31.7 µg/m³Peterborough, 15 July: 46.5 µg/m³BarrieBarrie, 9 July: 7.8 µg/m³Barrie, 10 July: 6.6 µg/m³Barrie, 11 July: 14.9 µg/m³Barrie, 12 July: 27.0 µg/m³, 2.9× its usual 9.4Barrie, 13 July: 15.5 µg/m³Barrie, 14 July: 22.7 µg/m³Barrie, 15 July: 76.1 µg/m³OttawaOttawa, 9 July: 7.6 µg/m³Ottawa, 10 July: 15.1 µg/m³Ottawa, 11 July: 22.4 µg/m³Ottawa, 12 July: 26.8 µg/m³, 3.5× its usual 7.7Ottawa, 13 July: 16.4 µg/m³Ottawa, 14 July: 21.5 µg/m³Ottawa, 15 July: 14.1 µg/m³BellevilleBelleville, 9 July: 6.1 µg/m³Belleville, 10 July: 9.3 µg/m³Belleville, 11 July: 13.6 µg/m³Belleville, 12 July: 26.5 µg/m³, 3.8× its usual 7.0Belleville, 13 July: 13.4 µg/m³Belleville, 14 July: 39.5 µg/m³Belleville, 15 July: 45.1 µg/m³KingstonKingston, 9 July: 5.0 µg/m³Kingston, 10 July: 10.0 µg/m³Kingston, 11 July: 15.4 µg/m³Kingston, 12 July: 26.5 µg/m³, 3.4× its usual 7.7Kingston, 13 July: 10.0 µg/m³Kingston, 14 July: 26.8 µg/m³Kingston, 15 July: 37.7 µg/m³Parry SoundParry Sound, 9 July: 5.7 µg/m³Parry Sound, 10 July: 6.8 µg/m³Parry Sound, 11 July: 16.8 µg/m³Parry Sound, 12 July: 25.7 µg/m³, 3.3× its usual 7.7Parry Sound, 13 July: 11.9 µg/m³Parry Sound, 14 July: 21.8 µg/m³Parry Sound, 15 July: 88.7 µg/m³9 Jul101112131415
Every counted city, in the order the episode reached them, 3 days before to 3 after. Each square is a day, coloured by that day's PM2.5; outlined: at twice the city's usual or more.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

Every city it reached

CityDaysHighestUsualAbove usual
GatineauQuebec, Canada1 36.612 July6.35.8×
PeterboroughOntario, Canada1 31.812 July7.54.2×
BellevilleOntario, Canada1 26.512 July7.03.8×
OttawaOntario, Canada1 26.812 July7.73.5×
KingstonOntario, Canada1 26.512 July7.73.4×
Parry SoundOntario, Canada1 25.712 July7.73.3×
NepeanOntario, Canada1 41.912 July14.32.9×
BarrieOntario, Canada1 27.012 July9.42.9×

Daily means in µg/m³, over the days each city counted in this episode. Highest: its highest of those days. Usual: the city's median for the time of year of that day (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that, with a usual under 5 µg/m³ taken as 5.

Against other episodes in Canada

Number 43 of 43 episodes in Canada since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 43.

Use this page

SmogRank, Ontario and Quebec, Canada, July 2026: 8 cities with PM2.5 at twice their usual or more, 12 July 2026, smogrank.com/episodes/2026-07-ontario-and-quebec-canada (accessed 5 October 2026).

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms.

An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes. Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source. Fire detections from NASA FIRMS; smoke maps from NOAA HMS.