São Paulo, Brazil Air Quality & Smog

Dominant pollutants, when pollution and smog are worst, a notable historical episode, and the official monitoring agencies for São Paulo, Brazil — plus how to check the current reading. São Paulo reports air quality on the Brazil’s air-quality index (CETESB), not the US AQI — our guide to world air-quality indices explains how the major scales compare.

Dominant pollutants

Ozone, PM2.5, NO₂ (Latin America's largest vehicle fleet).

Seasonal pattern: when smog is worst

São Paulo's air is shaped by the largest vehicle fleet in Latin America, including its distinctive ethanol–gasoline mix. Ozone is a year-round challenge driven by traffic and strong sun; the dry winter months (May–September) worsen particulate. Sugarcane-burning smoke historically affected the state's interior.

A notable air-quality episode

The metro region regularly exceeds Brazil's ozone standard, and the state environmental agency CETESB — one of Latin America's most respected — issues regular air-quality bulletins and episode alerts.

The local index and who runs it

São Paulo reports air quality using the Brazil’s air-quality index (CETESB), not the US AQI — so the same air can read as a different number than you may be used to. CETESB publishes a well-regarded air-quality index and station network for São Paulo state; see our world air-quality indices guide for context.

• CETESB (São Paulo State Environmental Agency)

How to check air quality in São Paulo

For the official live reading, the agency portals above are the canonical source. To understand what the numbers mean, see our guide to world air-quality indices and how they compare to the US AQI. Smog Report puts glanceable air quality on your iPhone — widgets, Live Activities, Siri, and Apple Watch — free and with no account.

Common questions about São Paulo air quality

Why does São Paulo have air-quality and smog problems?

São Paulo's air is shaped by the largest vehicle fleet in Latin America, including its distinctive ethanol–gasoline mix. Ozone is a year-round challenge driven by traffic and strong sun; the dry winter months (May–September) worsen particulate. Sugarcane-burning smoke historically affected the state's interior.

What are the main air pollutants in São Paulo?

São Paulo's dominant pollutants are ozone, PM2.5, NO₂ (Latin America's largest vehicle fleet). The reading on any given day is usually driven by whichever of these is highest.

Has São Paulo had a major air-quality or smog event?

The metro region regularly exceeds Brazil's ozone standard, and the state environmental agency CETESB — one of Latin America's most respected — issues regular air-quality bulletins and episode alerts.

What air-quality index does São Paulo use?

São Paulo reports air quality on the Brazil’s air-quality index (CETESB) (index), not the US AQI — so the same air can read as a different number than you may be used to. For live, glanceable readings on your iPhone, the free Smog Report app auto-selects the right local index for wherever you are.

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