SmogRank / Episodes / Brazil

São Paulo and Rio de Janeiro, Brazil, May 2026

For 2 days, from 15 to 16 May 2026, 8 cities in Brazil had PM2.5 at least twice their usual for the time of year. The worst reading was Nilópolis, Rio de Janeiro, Brazil: 47.6 µg/m³ on 16 May, about 3.1× its usual 15.3. Ended 16 May.

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
Days215 to 16 May 2026
Worst day15 May5 cities counted
Furthest above usual3.9×Duque de Caxias

Day by day

15 May 5 cities at twice their usual or more
São José dos CamposItaquaquecetubaFerraz de VasconcelosSantosBarra da TijucaAcariRio de JaneiroPaulíniaLimeiraPiracicabaRibeirão PretoBauruSão PauloSanto AndréTaubatéGuaratinguetáCubatãoItaguaíNilópolisDuque de Caxias

No fire and smoke map for this day.

12 May13141516171819
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 4 of the 8 days shown.

Fires: NASA FIRMS (VIIRS). Traced smoke: NOAA Hazard Mapping System. Volcanic ash: aviation ash warnings (SIGMETs) via NOAA's Aviation Weather Center.

How it spread

Santo AndréSanto André, 12 May: 12.7 µg/m³Santo André, 13 May: 28.9 µg/m³Santo André, 14 May: 37.9 µg/m³Santo André, 15 May: 32.6 µg/m³, 2.2× its usual 14.7Santo André, 16 May: 30.3 µg/m³, 2.0× its usual 14.8Santo André, 17 May: 12.5 µg/m³Santo André, 18 May: 6.6 µg/m³Santo André, 19 May: 2.3 µg/m³São PauloSão Paulo, 12 May: 18.9 µg/m³São Paulo, 13 May: 27.8 µg/m³São Paulo, 14 May: 34.4 µg/m³São Paulo, 15 May: 30.5 µg/m³, 2.0× its usual 15.2São Paulo, 16 May: 21.1 µg/m³São Paulo, 17 May: 12.7 µg/m³São Paulo, 18 May: 7.5 µg/m³São Paulo, 19 May: 4.7 µg/m³CubatãoCubatão, 12 May: 10.8 µg/m³Cubatão, 13 May: 22.6 µg/m³Cubatão, 14 May: 20.4 µg/m³Cubatão, 15 May: 25.8 µg/m³, 2.5× its usual 10.3Cubatão, 16 May: 16.4 µg/m³Cubatão, 17 May: 10.6 µg/m³Cubatão, 18 May: 5.4 µg/m³Cubatão, 19 May: 6.7 µg/m³GuaratinguetáGuaratinguetá, 12 May: 12.9 µg/m³Guaratinguetá, 13 May: 14.4 µg/m³Guaratinguetá, 14 May: 17.0 µg/m³Guaratinguetá, 15 May: 25.8 µg/m³, 2.3× its usual 11.0Guaratinguetá, 16 May: 17.9 µg/m³Guaratinguetá, 17 May: 18.0 µg/m³Guaratinguetá, 18 May: 9.1 µg/m³Guaratinguetá, 19 May: 6.8 µg/m³TaubatéTaubaté, 12 May: 10.8 µg/m³Taubaté, 13 May: 20.7 µg/m³Taubaté, 14 May: 17.5 µg/m³Taubaté, 15 May: 25.5 µg/m³, 2.3× its usual 11.1Taubaté, 16 May: 19.9 µg/m³Taubaté, 17 May: 18.5 µg/m³Taubaté, 18 May: 9.7 µg/m³Taubaté, 19 May: 5.7 µg/m³NilópolisNilópolis, 12 May: 10.2 µg/m³Nilópolis, 13 May: 24.7 µg/m³Nilópolis, 14 May: 27.5 µg/m³Nilópolis, 15 May: 23.9 µg/m³Nilópolis, 16 May: 47.6 µg/m³, 3.1× its usual 15.3Nilópolis, 17 May: 51.8 µg/m³Nilópolis, 18 May: 21.8 µg/m³Nilópolis, 19 May: 6.2 µg/m³ItaguaíItaguaí, 12 May: 10.5 µg/m³Itaguaí, 13 May: 17.1 µg/m³Itaguaí, 14 May: 19.1 µg/m³Itaguaí, 15 May: 17.9 µg/m³Itaguaí, 16 May: 32.8 µg/m³, 3.0× its usual 10.9Itaguaí, 17 May: 42.0 µg/m³Itaguaí, 18 May: 13.0 µg/m³Itaguaí, 19 May: 3.9 µg/m³Duque de CaxiasDuque de Caxias, 12 May: 11.3 µg/m³Duque de Caxias, 13 May: 19.2 µg/m³Duque de Caxias, 14 May: 22.6 µg/m³Duque de Caxias, 15 May: 14.8 µg/m³Duque de Caxias, 16 May: 31.6 µg/m³, 3.9× its usual 8.1Duque de Caxias, 17 May: 25.0 µg/m³Duque de Caxias, 18 May: 13.3 µg/m³Duque de Caxias, 19 May: 6.2 µg/m³12 May13141516171819
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
Duque de CaxiasRio de Janeiro, Brazil1 31.616 May8.13.9×
NilópolisRio de Janeiro, Brazil1 47.616 May15.33.1×
ItaguaíRio de Janeiro, Brazil1 32.816 May10.93.0×
CubatãoSão Paulo, Brazil1 25.815 May10.32.5×
GuaratinguetáSão Paulo, Brazil1 25.815 May11.02.3×
TaubatéSão Paulo, Brazil1 25.515 May11.12.3×
Santo AndréSão Paulo, Brazil2 32.615 May14.72.2×
São PauloSão Paulo, Brazil1 30.515 May15.22.0×

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 15 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 Rio de Janeiro, Brazil, May 2026: 8 cities with PM2.5 at twice their usual or more, 15 to 16 May 2026, smogrank.com/episodes/2026-05-sao-paulo-and-rio-de-janeiro-brazil (accessed 12 October 2026).

Download top 10 (PNG)

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 2026. Neither the European Commission nor ECMWF is responsible for any use that may be made of the Copernicus information or data it contains.