São Paulo Air Quality
Brazil's megacity of 22 million faces chronic vehicle pollution and seasonal Amazon fire smoke that can darken skies 2,500 km from the fires.
Monthly AQI Pattern
August–September peak driven by Amazon biomass burning smoke
Pollutant Breakdown
The Two Pollution Seasons
🔥 Burning Season (Jul–Oct)
Amazon and Cerrado fires peak August–September. Smoke plumes from tens of thousands of fires travel on southeast trade winds to São Paulo. PM2.5 can exceed 50–100 μg/m³ on the worst days. INPE satellite data shows fire hotspots; IQAir sensors show the real-time PM2.5 impact over the city.
🚗 Dry Season Traffic (May–Aug)
São Paulo's austral winter (May–August) brings dry air and temperature inversions that trap vehicle exhaust over the city. Average commute speeds on SP expressways drop to 12–18 km/h during rush hours. Stop-and-go diesel trucks and buses produce concentrated PM2.5 and NO₂ in corridor neighborhoods.
10 Million Vehicles
São Paulo's vehicle fleet has grown from 3.5M in 1990 to over 10M in 2024 — more cars than countries like Portugal or Sweden. Brazil's road-centric urban planning, low public transport coverage outside the metro core, and historically subsidized fuel prices have all contributed.
The rodízio municipal (rotating traffic restriction) bans each vehicle from the expanded center one weekday, reducing peak traffic by ~15–20%. It was the first such program in Latin America (1997), but critics argue it has limited effectiveness as households buy second cars to bypass restrictions.
CETESB monitoring shows that vehicle emissions fell ~30% per km driven since 2000 due to cleaner fuel standards (PROCONVE/P7 diesel) and catalytic converters. But total fleet growth has outpaced per-vehicle improvements, keeping overall emissions stable.
Health Advisory
Unusually sensitive individuals should consider limiting prolonged outdoor exertion. Otherwise normal activity is fine.
Sensitive groups (children, elderly, asthma) should reduce outdoor time. Wear N95/PFF2 during smoky days. Keep windows closed during peak smoke events.
Air improves with summer rains. Normal activity safe for healthy adults. Check CETESB real-time data for current conditions.
Frequently Asked Questions
What is São Paulo's AQI in 2024?
São Paulo's annual average AQI in 2024 was approximately 65 (Moderate category). PM2.5 averaged 14.2 μg/m³ — about 2.8× above the WHO annual guideline of 5 μg/m³.
When is air quality worst in São Paulo?
Air quality is worst August–September during Brazil's Amazon burning season. Smoke from thousands of fires in the Amazon and Cerrado regions travels to São Paulo, pushing AQI above 100–150 for weeks. Winter (June–July) also sees elevated PM2.5 due to thermal inversions.
Why does São Paulo have so much vehicle pollution?
São Paulo has over 10 million registered vehicles in a metro area of 22 million people. Brazil's road-centric transport model, relatively low fuel taxes, and sparse metro coverage mean the car is the dominant transport mode. CETESB data shows vehicle exhaust contributes ~70% of urban PM2.5.
What is CETESB and what does it monitor?
CETESB is São Paulo State's Environmental Agency, operating 60+ air quality monitoring stations across the metro area. It measures PM2.5, PM10, O₃, NO₂, SO₂, and CO. Data is updated hourly and publicly available. São Paulo is one of the best-monitored cities in Latin America.
Should I wear a mask in São Paulo?
On typical days with AQI below 100, a mask is not necessary for healthy adults. During August–September fire season, when AQI regularly exceeds 100–150, sensitive groups (children, elderly, asthma patients) should wear N95/PFF2 masks outdoors and keep windows closed. Check CETESB's real-time data before extended outdoor exercise.