SmogRank / Brazil / Rio de Janeiro / Rio de Janeiro
Rio de Janeiro, month by month
Rio de Janeiro has a measured daily mean on 1,025 days since 25 August 2023. Its worst month was June 2024, at 77 US AQI (22.9 µg/m³), 74th of 2,563 cities on that month's world ranking. Its cleanest was October 2023, at 25 US AQI (4.5 µg/m³). 2025 averaged 48 US AQI (8.7 µg/m³), against 58 US AQI (12.9 µg/m³) in 2024.
Every month since 2023
The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales
Months without a mean, and why
5 months
| Month | Why |
|---|---|
| Jun 2025 | 14 of 30 days measured; a month needs 21. The others: 14 with no readings from the monitors, 2 with readings for part of the day (a day needs 18 hours). |
| Apr 2025 | 18 of 30 days measured; a month needs 21. The others: 11 with no readings from the monitors, 1 with readings for part of the day (a day needs 18 hours). |
| May 2024 | 21 of 31 days measured; a month needs 22. The others: 9 with no readings from the monitors, 1 with readings for part of the day (a day needs 18 hours). |
| Apr 2024 | 7 of 30 days measured; a month needs 21. The others: 22 with no readings from the monitors, 1 with readings for part of the day (a day needs 18 hours). |
| Aug 2023 | 4 of 31 days measured; a month needs 22. The others: 3 with readings for part of the day (a day needs 18 hours). |
A day counts once 18 hours of it are measured; a month needs 70% of its days.
Rio de Janeiro's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| June 2024 | 7722.9 µg/m³ | 74thof 2,563 | São Paulo, Minas Gerais and Rio de Janeiro, Brazil, June 2024 Southern Brazil, 20 to 22 June 2024and 2 more |
| September 2024 | 7521.9 µg/m³ | 89thof 2,010 | Southern Brazil, 30 September to 4 October 2024 Southern Brazil, 22 to 28 September 2024and 2 more |
| July 2024 | 6918.9 µg/m³ | 112thof 2,566 | Southern Brazil, 25 to 28 July 2024 Southern Brazil, 4 to 5 July 2024 |
| August 2024 | 6818.2 µg/m³ | 118thof 2,010 | Southern Brazil, 30 August to 5 September 2024 Southern Brazil, 22 to 25 August 2024and 1 more |
| July 2025 | 6215.1 µg/m³ | 398thof 2,889 | Southern Brazil, July 2025 |
| December 2023 | 5511.2 µg/m³ | 506thof 2,247 | – |
Monthly means over the days measured; finished months only. World rank: its place on that month's world ranking of every city with enough days. Each month opens that ranking.
Rio de Janeiro's worst days
| Day | US AQI | Episode |
|---|---|---|
| 18 Aug 2024 | 15257.5 µg/m³ | Southern Brazil, 15 to 22 August 2024 |
| 28 Jul 2024 | 13549.2 µg/m³ | Southern Brazil, 25 to 28 July 2024 |
| 27 Jul 2024 | 12043.1 µg/m³ | Southern Brazil, 25 to 28 July 2024 |
| 20 Jun 2024 | 11942.9 µg/m³ | Southern Brazil, 20 to 22 June 2024 |
| 17 Aug 2024 | 11541.1 µg/m³ | Southern Brazil, 15 to 22 August 2024 |
| 21 Jun 2024 | 11340.3 µg/m³ | Southern Brazil, 20 to 22 June 2024 |
| 13 Sept 2024 | 11240.1 µg/m³ | Southern Brazil, 7 to 17 September 2024 |
| 24 Sept 2023 | 11240.0 µg/m³ | – |
| 12 Jun 2024 | 10938.9 µg/m³ | Southern Brazil, 11 to 13 June 2024 |
| 5 Jul 2024 | 10637.7 µg/m³ | Southern Brazil, 4 to 5 July 2024 |
Daily means, the highest since 25 Aug 2023; the WHO's daily guideline is 15 µg/m³. Each date opens that day's world ranking, and each episode the bad-air spell it was part of.
Use this history
SmogRank, PM2.5 monthly and daily means, Rio de Janeiro, Brazil, 25 Aug 2023 – 11 Oct 2026. Monitor data from Rio City Hall via OpenAQ; sources listed at smogrank.com/sources. smogrank.com/br/rio-de-janeiro/history (accessed 12 Oct 2026).
You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.
Rio de Janeiro now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 20:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index. Some low-cost readings: Sensor.Community, ODbL (data and licence). Some readings: Uzhydromet (Uzbekistan's Hydrometeorological Service); Department of Environment, Nepal; Vietnam's government monitors; Aurassure; Umhverfisstofnun (Environment Agency of Iceland); RMCAB (Secretaría Distrital de Ambiente, Bogotá); Love My Air (City and County of Denver), no reuse terms published (why we use them).