São Paulo and Minas Gerais, Brazil, September 2024
For 2 days, from 20 to 21 September 2024, 8 cities in Brazil had PM2.5 at least twice their usual for the time of year. The worst reading was Ribeirão Preto, São Paulo, Brazil: 54.9 µg/m³ on 20 September, about 3.2× its usual 17.4. Ended 21 September.
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
Days220 to 21 September 2024
Worst day20 September5 cities counted
Furthest above usual3.2×Ribeirão Preto
Day by day
On the map: 870 fire detections.
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.
Fires, seenHeat NASA satellites detected that day; bigger and glowing means more detections in the area. Farm burning and other fires count too, not only wildfires.
Under the cities, for each UTC day: fires NASA satellites detected, smoke NOAA analysts traced and volcanic ash warnings for aircraft. They show what was in the air, not that it caused the readings. Mapped for 6 of the 8 days shown.
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.
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 Brazil
Number 17 of 20 episodes in Brazil since our records began, by cities reached.
Bars: cities reached; colour: the level of the episode's highest daily reading. All 20.
Use this page
SmogRank, São Paulo and Minas Gerais, Brazil, September 2024: 8 cities with PM2.5 at twice their usual or more, 20 to 21 September 2024, smogrank.com/episodes/2024-09-sao-paulo-and-minas-gerais-brazil (accessed 12 October 2026).
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. Dust: contains modified Copernicus Atmosphere Monitoring Service information 2024. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.
