SmogRank / French Guiana / Guyane / Cayenne

Cayenne, month by month

Cayenne has a measured daily mean on 884 days since 5 January 2023. Its worst month was February 2024, at 80 US AQI (24.4 µg/m³), 144th of 2,486 cities on that month's world ranking. Its cleanest was June 2023, at 18 US AQI (3.3 µg/m³).

Every month since 2023

202653 so far246 days measured940th of 2,791 in the world
Jan13 daysFeb80#400Mar44#2,137Apr57#715May47#1,136Jun18 daysJul38#2,210Aug52#917Sep47#910Oct34#1,672
2025too few days for a mean (a year needs 256)230 days measured
Jan21 daysFeb52#1,221Mar18 daysApr12 daysMay19 daysJun13 daysJul29#2,571Aug36#2,366Sep54#611Oct11 daysNov39#1,843Dec13 days
2024too few days for a mean (a year needs 257)149 days measured
Jan62#467Feb80#144Mar14 daysApr16 daysMaynoneJunnoneJul1 dayAug6 daysSepnoneOct14 daysNov32#2,078Dec21 days
202344 for the year259 days measured876th of 1,355 in the world
Jan9 daysFeb49#740Mar56#160Apr58#220May28#1,419Jun18#1,546Jul21 daysAug12 daysSep20 daysOct7 daysNov48#969Dec51#894
Each square is a month's mean PM2.5 in US AQI from Cayenne's measured days, with its place on that month's world ranking under it. A month has a mean once 70% of its days are measured, the rule the monthly rankings use; under that, the square gives the days measured. Each square opens that month's ranking with Cayenne marked; each year, the year's. A dashed square is the running month, so far.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

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

23 months
MonthWhy
Jun 202618 of 30 days measured; a month needs 21. The others: 12 with under 18 hours of readings or readings that failed our checks.
Jan 202613 of 31 days measured; a month needs 22. The others: 18 with under 18 hours of readings or readings that failed our checks.
Dec 202513 of 31 days measured; a month needs 22. The others: 18 with under 18 hours of readings or readings that failed our checks.
Oct 202511 of 31 days measured; a month needs 22. The others: 20 with under 18 hours of readings or readings that failed our checks.
Jun 202513 of 30 days measured; a month needs 21. The others: 17 with under 18 hours of readings or readings that failed our checks.
May 202519 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks.
Apr 202512 of 30 days measured; a month needs 21. The others: 18 with under 18 hours of readings or readings that failed our checks.
Mar 202518 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks.
Jan 202521 of 31 days measured; a month needs 22. The others: 10 with under 18 hours of readings or readings that failed our checks.
Dec 202421 of 31 days measured; a month needs 22. The others: 10 with under 18 hours of readings or readings that failed our checks.
Oct 202414 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks.
Sep 2024No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Aug 20246 of 31 days measured; a month needs 22. The others: 25 with under 18 hours of readings or readings that failed our checks.
Jul 20241 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks.
Jun 2024No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
May 2024No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Apr 202416 of 30 days measured; a month needs 21. The others: 14 with under 18 hours of readings or readings that failed our checks.
Mar 202414 of 31 days measured; a month needs 22. The others: 17 with under 18 hours of readings or readings that failed our checks.
Oct 20237 of 31 days measured; a month needs 22. The others: 24 with under 18 hours of readings or readings that failed our checks.
Sep 202320 of 30 days measured; a month needs 21. The others: 10 with under 18 hours of readings or readings that failed our checks.
Aug 202312 of 31 days measured; a month needs 22. The others: 19 with under 18 hours of readings or readings that failed our checks.
Jul 202321 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 9 with under 18 hours of readings or readings that failed our checks.
Jan 20239 of 31 days measured; a month needs 22. The others: 18 with under 18 hours of readings or readings that failed our checks.

A day counts once 18 hours of it are measured; a month needs 70% of its days.

Cayenne's worst months

MonthUS AQIDays measuredWorld rank
February 2024 8024.4 µg/m³27 of 29144thof 2,486
February 2026 8024.4 µg/m³25 of 28400thof 2,866
January 2024 6214.9 µg/m³28 of 31467thof 2,385
April 2023 5812.8 µg/m³28 of 30220thof 1,622
April 2026 5712.1 µg/m³29 of 30715thof 2,941
March 2023 5611.9 µg/m³26 of 31160thof 911

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.

Cayenne's worst days

DayUS AQI
22 Feb 2026 184103.0 µg/m³
31 Jan 2024 17589.6 µg/m³
30 Jan 2024 17488.2 µg/m³
21 Feb 2026 15866.0 µg/m³
24 Dec 2024 13448.8 µg/m³
23 Dec 2024 12947.0 µg/m³
1 Feb 2024 12846.6 µg/m³
25 Feb 2024 11742.0 µg/m³
23 Feb 2026 11641.6 µg/m³
24 Feb 2024 11641.5 µg/m³

Daily means, the highest since 5 Jan 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, Cayenne, French Guiana, 5 Jan 2023 – 11 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/gf/cayenne/history (accessed 12 Oct 2026).

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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.

Cayenne now: the last 24 hours, its ranks today and the last 12 months day by day.

Updated 2026-10-12 19:07 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).