SmogRank / Portugal / Azores

Air quality in Horta

Azores, Portugal.

Latest hour14US AQI
Good

PM2.5 2.5 µg/m³, 0.2× the WHO 24-hour guideline, at local time on 4 Oct. Too few hours in the last 24 for a 24-hour average.

Where Horta ranks

24 hours–not enough data
7 days–not enough data
30 days–not enough data
This year–not enough data

The last 12 months, day by day

1102031Nov 2025DecJan 2026FebMarAprMayJunJulAugSepOct2025-11-01: 4.8 µg/m³2025-11-02: 2.0 µg/m³2025-11-03: no daily value, only 16 of the 18 hours a day needs2025-11-04: no daily value, only 17 of the 18 hours a day needs2025-11-05: no daily value, only 16 of the 18 hours a day needs2025-11-06: no daily value, only 6 of the 18 hours a day needs2025-11-07: no daily value, only 13 of the 18 hours a day needs2025-11-08: no daily value, only 14 of the 18 hours a day needs2025-11-09: 4.2 µg/m³2025-11-10: no daily value, only 13 of the 18 hours a day needs2025-11-11: no daily value, only 4 of the 18 hours a day needs2025-11-12: no daily value, only 5 of the 18 hours a day needs2025-11-13: no daily value, only 9 of the 18 hours a day needs2025-11-14: no daily value, no readings from the monitor2025-11-15: no daily value, no readings from the monitor2025-11-16: no daily value, no readings from the monitor2025-11-17: no daily value, no readings from the monitor2025-11-18: no daily value, only 1 of the 18 hours a day needs2025-11-19: no daily value, only 9 of the 18 hours a day needs2025-11-20: no daily value, only 7 of the 18 hours a day needs2025-11-21: no daily value, only 12 of the 18 hours a day needs2025-11-22: no daily value, only 15 of the 18 hours a day needs2025-11-23: no daily value, only 15 of the 18 hours a day needs2025-11-24: 1.3 µg/m³2025-11-25: no daily value, only 13 of the 18 hours a day needs2025-11-26: no daily value, only 15 of the 18 hours a day needs2025-11-27: no daily value, only 12 of the 18 hours a day needs2025-11-28: no daily value, only 8 of the 18 hours a day needs2025-11-29: no daily value, only 2 of the 18 hours a day needs2025-11-30: no daily value, only 3 of the 18 hours a day needs2025-12-01: no daily value, only 10 of the 18 hours a day needs2025-12-02: no daily value, only 15 of the 18 hours a day needs2025-12-03: no daily value, only 17 of the 18 hours a day needs2025-12-04: 1.5 µg/m³2025-12-05: no daily value, only 17 of the 18 hours a day needs2025-12-06: no daily value, only 14 of the 18 hours a day needs2025-12-07: 2.8 µg/m³2025-12-08: 2.9 µg/m³2025-12-09: no daily value, only 16 of the 18 hours a day needs2025-12-10: no daily value, only 17 of the 18 hours a day needs2025-12-11: no daily value, only 17 of the 18 hours a day needs2025-12-12: 6.3 µg/m³2025-12-13: 4.0 µg/m³2025-12-14: no daily value, only 14 of the 18 hours a day needs2025-12-15: 5.7 µg/m³2025-12-16: no daily value, only 16 of the 18 hours a day needs2025-12-17: 3.4 µg/m³2025-12-18: no daily value, only 16 of the 18 hours a day needs2025-12-19: no daily value, only 14 of the 18 hours a day needs2025-12-20: 10.1 µg/m³2025-12-21: no daily value, only 16 of the 18 hours a day needs2025-12-22: no daily value, only 15 of the 18 hours a day needs2025-12-23: no daily value, only 17 of the 18 hours a day needs2025-12-24: no daily value, only 15 of the 18 hours a day needs2025-12-25: no daily value, only 15 of the 18 hours a day needs2025-12-26: no daily value, only 15 of the 18 hours a day needs2025-12-27: no daily value, only 16 of the 18 hours a day needs2025-12-28: 0.9 µg/m³2025-12-29: no daily value, only 16 of the 18 hours a day needs2025-12-30: no daily value, only 16 of the 18 hours a day needs2025-12-31: no daily value, only 17 of the 18 hours a day needs2026-01-01: no daily value, only 14 of the 18 hours a day needs2026-01-02: no daily value, only 14 of the 18 hours a day needs2026-01-03: no daily value, only 17 of the 18 hours a day needs2026-01-04: no daily value, only 14 of the 18 hours a day needs2026-01-05: 3.4 µg/m³2026-01-06: no daily value, only 7 of the 18 hours a day needs2026-01-07: no daily value, only 2 of the 18 hours a day needs2026-01-08: no daily value, only 10 of the 18 hours a day needs2026-01-09: no daily value, only 9 of the 18 hours a day needs2026-01-10: no daily value, only 10 of the 18 hours a day needs2026-01-11: no daily value, only 16 of the 18 hours a day needs2026-01-12: no daily value, only 5 of the 18 hours a day needs2026-01-13: no daily value, no readings from the monitor2026-01-14: no daily value, no readings from the monitor2026-01-15: no daily value, no readings from the monitor2026-01-16: no daily value, no readings from the monitor2026-01-17: no daily value, no readings from the monitor2026-01-18: no daily value, no readings from the monitor2026-01-19: no daily value, no readings from the monitor2026-01-20: no daily value, no readings from the monitor2026-01-21: no daily value, no readings from the monitor2026-01-22: no daily value, no readings from the monitor2026-01-23: no daily value, no readings from the monitor2026-01-24: no daily value, no readings from the monitor2026-01-25: no daily value, no readings from the monitor2026-01-26: no daily value, no readings from the monitor2026-01-27: no daily value, no readings from the monitor2026-01-28: no daily value, no readings from the monitor2026-01-29: no daily value, no readings from the monitor2026-01-30: no daily value, no readings from the monitor2026-01-31: no daily value, no readings from the monitor2026-02-01: no daily value, no readings from the monitor2026-02-02: no daily value, no readings from the monitor2026-02-03: no daily value, no readings from the monitor2026-02-04: no daily value, no readings from the monitor2026-02-05: no daily value, no readings from the monitor2026-02-06: no daily value, no readings from the monitor2026-02-07: no daily value, no readings from the monitor2026-02-08: no daily value, no readings from the monitor2026-02-09: no daily value, no readings from the monitor2026-02-10: no daily value, no readings from the monitor2026-02-11: no daily value, no readings from the monitor2026-02-12: no daily value, no readings from the monitor2026-02-13: no daily value, no readings from the monitor2026-02-14: no daily value, no readings from the monitor2026-02-15: no daily value, no readings from the monitor2026-02-16: no daily value, no readings from the monitor2026-02-17: no daily value, no readings from the monitor2026-02-18: no daily value, no readings from the monitor2026-02-19: no daily value, no readings from the monitor2026-02-20: no daily value, no readings from the monitor2026-02-21: no daily value, only 6 of the 18 hours a day needs2026-02-22: no daily value, only 11 of the 18 hours a day needs2026-02-23: no daily value, only 12 of the 18 hours a day needs2026-02-24: no daily value, only 17 of the 18 hours a day needs2026-02-25: no daily value, only 17 of the 18 hours a day needs2026-02-26: no daily value, only 16 of the 18 hours a day needs2026-02-27: no daily value, only 15 of the 18 hours a day needs2026-02-28: no daily value, only 15 of the 18 hours a day needs2026-03-01: no daily value, only 15 of the 18 hours a day needs2026-03-02: 4.4 µg/m³2026-03-03: 3.6 µg/m³2026-03-04: 1.2 µg/m³2026-03-05: 2.1 µg/m³2026-03-06: no daily value, only 17 of the 18 hours a day needs2026-03-07: 1.7 µg/m³2026-03-08: 2.6 µg/m³2026-03-09: 2.6 µg/m³2026-03-10: no daily value, only 16 of the 18 hours a day needs2026-03-11: 0.9 µg/m³2026-03-12: 0.8 µg/m³2026-03-13: 1.3 µg/m³2026-03-14: 2.0 µg/m³2026-03-15: 2.0 µg/m³2026-03-16: 0.9 µg/m³2026-03-17: no daily value, only 17 of the 18 hours a day needs2026-03-18: 2.6 µg/m³2026-03-19: 3.8 µg/m³2026-03-20: 5.2 µg/m³2026-03-21: no daily value, only 17 of the 18 hours a day needs2026-03-22: 4.7 µg/m³2026-03-23: 4.8 µg/m³2026-03-24: no daily value, only 17 of the 18 hours a day needs2026-03-25: no daily value, only 17 of the 18 hours a day needs2026-03-26: 1.5 µg/m³2026-03-27: 1.7 µg/m³2026-03-28: no daily value, only 10 of the 18 hours a day needs2026-03-29: no daily value, no readings from the monitor2026-03-30: no daily value, only 8 of the 18 hours a day needs2026-03-31: no daily value, only 13 of the 18 hours a day needs2026-04-01: 3.7 µg/m³2026-04-02: 1.1 µg/m³2026-04-03: no daily value, only 16 of the 18 hours a day needs2026-04-04: 1.0 µg/m³2026-04-05: no daily value, only 17 of the 18 hours a day needs2026-04-06: 2.7 µg/m³2026-04-07: no daily value, only 16 of the 18 hours a day needs2026-04-08: no daily value, only 17 of the 18 hours a day needs2026-04-09: 2.1 µg/m³2026-04-10: no daily value, only 15 of the 18 hours a day needs2026-04-11: 2.5 µg/m³2026-04-12: no daily value, only 17 of the 18 hours a day needs2026-04-13: no daily value, only 17 of the 18 hours a day needs2026-04-14: 2.3 µg/m³2026-04-15: no daily value, only 16 of the 18 hours a day needs2026-04-16: 1.8 µg/m³2026-04-17: no daily value, only 17 of the 18 hours a day needs2026-04-18: 1.0 µg/m³2026-04-19: no daily value, only 16 of the 18 hours a day needs2026-04-20: no daily value, only 17 of the 18 hours a day needs2026-04-21: 3.2 µg/m³2026-04-22: 2.4 µg/m³2026-04-23: no daily value, only 15 of the 18 hours a day needs2026-04-24: no daily value, only 17 of the 18 hours a day needs2026-04-25: 1.9 µg/m³2026-04-26: no daily value, only 16 of the 18 hours a day needs2026-04-27: 1.6 µg/m³2026-04-28: no daily value, only 13 of the 18 hours a day needs2026-04-29: no daily value, only 13 of the 18 hours a day needs2026-04-30: no daily value, only 11 of the 18 hours a day needs2026-05-01: no daily value, only 7 of the 18 hours a day needs2026-05-02: no daily value, only 8 of the 18 hours a day needs2026-05-03: no daily value, only 11 of the 18 hours a day needs2026-05-04: no daily value, only 7 of the 18 hours a day needs2026-05-05: no daily value, only 17 of the 18 hours a day needs2026-05-06: no daily value, only 17 of the 18 hours a day needs2026-05-07: 2.3 µg/m³2026-05-08: no daily value, only 17 of the 18 hours a day needs2026-05-09: no daily value, only 16 of the 18 hours a day needs2026-05-10: no daily value, only 5 of the 18 hours a day needs2026-05-11: no daily value, only 15 of the 18 hours a day needs2026-05-12: no daily value, only 7 of the 18 hours a day needs2026-05-13: no daily value, only 15 of the 18 hours a day needs2026-05-14: no daily value, only 8 of the 18 hours a day needs2026-05-15: no daily value, only 13 of the 18 hours a day needs2026-05-16: no daily value, only 17 of the 18 hours a day needs2026-05-17: no daily value, only 14 of the 18 hours a day needs2026-05-18: 1.9 µg/m³2026-05-19: 1.9 µg/m³2026-05-20: no daily value, only 13 of the 18 hours a day needs2026-05-21: 1.4 µg/m³2026-05-22: 2.0 µg/m³2026-05-23: no daily value, only 14 of the 18 hours a day needs2026-05-24: no daily value, only 11 of the 18 hours a day needs2026-05-25: no daily value, only 10 of the 18 hours a day needs2026-05-26: no daily value, only 16 of the 18 hours a day needs2026-05-27: 0.9 µg/m³2026-05-28: 2.0 µg/m³2026-05-29: 3.7 µg/m³2026-05-30: 3.4 µg/m³2026-05-31: 1.5 µg/m³2026-06-01: 3.1 µg/m³2026-06-02: 5.3 µg/m³2026-06-03: 3.5 µg/m³2026-06-04: 2.9 µg/m³2026-06-05: no daily value, only 14 of the 18 hours a day needs2026-06-06: 2.5 µg/m³2026-06-07: 4.5 µg/m³2026-06-08: no daily value, only 16 of the 18 hours a day needs2026-06-09: no daily value, only 10 of the 18 hours a day needs2026-06-10: no daily value, only 13 of the 18 hours a day needs2026-06-11: 0.6 µg/m³2026-06-12: no daily value, only 11 of the 18 hours a day needs2026-06-13: no daily value, only 10 of the 18 hours a day needs2026-06-14: no daily value, only 17 of the 18 hours a day needs2026-06-15: no daily value, only 15 of the 18 hours a day needs2026-06-16: no daily value, only 10 of the 18 hours a day needs2026-06-17: no daily value, only 14 of the 18 hours a day needs2026-06-18: no daily value, only 12 of the 18 hours a day needs2026-06-19: 0.0 µg/m³2026-06-20: no daily value, only 15 of the 18 hours a day needs2026-06-21: 2.9 µg/m³2026-06-22: no daily value, only 16 of the 18 hours a day needs2026-06-23: no daily value, only 17 of the 18 hours a day needs2026-06-24: 1.6 µg/m³2026-06-25: no daily value, only 17 of the 18 hours a day needs2026-06-26: 1.2 µg/m³2026-06-27: 2.1 µg/m³2026-06-28: 0.5 µg/m³2026-06-29: no daily value, only 17 of the 18 hours a day needs2026-06-30: no daily value, only 14 of the 18 hours a day needs2026-07-01: no daily value, only 16 of the 18 hours a day needs2026-07-02: no daily value, only 17 of the 18 hours a day needs2026-07-03: 2.4 µg/m³2026-07-04: no daily value, only 16 of the 18 hours a day needs2026-07-05: no daily value, only 13 of the 18 hours a day needs2026-07-06: no daily value, only 10 of the 18 hours a day needs2026-07-07: no daily value, only 13 of the 18 hours a day needs2026-07-08: no daily value, only 6 of the 18 hours a day needs2026-07-09: no daily value, only 14 of the 18 hours a day needs2026-07-10: 3.7 µg/m³2026-07-11: no daily value, only 16 of the 18 hours a day needs2026-07-12: no daily value, only 13 of the 18 hours a day needs2026-07-13: no daily value, only 15 of the 18 hours a day needs2026-07-14: no daily value, only 16 of the 18 hours a day needs2026-07-15: no daily value, only 14 of the 18 hours a day needs2026-07-16: no daily value, only 11 of the 18 hours a day needs2026-07-17: no daily value, only 14 of the 18 hours a day needs2026-07-18: no daily value, only 8 of the 18 hours a day needs2026-07-19: no daily value, only 13 of the 18 hours a day needs2026-07-20: no daily value, only 16 of the 18 hours a day needs2026-07-21: 3.4 µg/m³2026-07-22: no daily value, only 12 of the 18 hours a day needs2026-07-23: no daily value, only 16 of the 18 hours a day needs2026-07-24: no daily value, only 12 of the 18 hours a day needs2026-07-25: no daily value, only 15 of the 18 hours a day needs2026-07-26: no daily value, only 8 of the 18 hours a day needs2026-07-27: no daily value, only 14 of the 18 hours a day needs2026-07-28: no daily value, only 16 of the 18 hours a day needs2026-07-29: 3.7 µg/m³2026-07-30: no daily value, only 16 of the 18 hours a day needs2026-07-31: no daily value, only 13 of the 18 hours a day needs2026-08-01: no daily value, only 17 of the 18 hours a day needs2026-08-02: no daily value, only 17 of the 18 hours a day needs2026-08-03: 2.6 µg/m³2026-08-04: no daily value, only 17 of the 18 hours a day needs2026-08-05: no daily value, only 12 of the 18 hours a day needs2026-08-06: no daily value, only 8 of the 18 hours a day needs2026-08-07: no daily value, only 13 of the 18 hours a day needs2026-08-08: no daily value, only 14 of the 18 hours a day needs2026-08-09: no daily value, only 16 of the 18 hours a day needs2026-08-10: no daily value, only 14 of the 18 hours a day needs2026-08-11: no daily value, only 17 of the 18 hours a day needs2026-08-12: no daily value, only 14 of the 18 hours a day needs2026-08-13: no daily value, only 16 of the 18 hours a day needs2026-08-14: 5.2 µg/m³2026-08-15: no daily value, only 17 of the 18 hours a day needs2026-08-16: 4.7 µg/m³2026-08-17: no daily value, only 16 of the 18 hours a day needs2026-08-18: 6.4 µg/m³2026-08-19: 4.3 µg/m³2026-08-20: no daily value, only 17 of the 18 hours a day needs2026-08-21: 4.0 µg/m³2026-08-22: 2.9 µg/m³2026-08-23: 5.9 µg/m³2026-08-24: no daily value, only 17 of the 18 hours a day needs2026-08-25: no daily value, only 14 of the 18 hours a day needs2026-08-26: no daily value, only 12 of the 18 hours a day needs2026-08-27: no daily value, only 14 of the 18 hours a day needs2026-08-28: no daily value, only 16 of the 18 hours a day needs2026-08-29: 1.5 µg/m³2026-08-30: no daily value, only 8 of the 18 hours a day needs2026-08-31: no daily value, only 7 of the 18 hours a day needs2026-09-01: no daily value, only 10 of the 18 hours a day needs2026-09-02: no daily value, only 11 of the 18 hours a day needs2026-09-03: no daily value, only 15 of the 18 hours a day needs2026-09-04: no daily value, only 11 of the 18 hours a day needs2026-09-05: no daily value, only 12 of the 18 hours a day needs2026-09-06: no daily value, only 14 of the 18 hours a day needs2026-09-07: 4.4 µg/m³2026-09-08: no daily value, only 17 of the 18 hours a day needs2026-09-09: 4.2 µg/m³2026-09-10: no daily value, only 16 of the 18 hours a day needs2026-09-11: 4.0 µg/m³2026-09-12: 3.4 µg/m³2026-09-13: no daily value, only 15 of the 18 hours a day needs2026-09-14: no daily value, only 6 of the 18 hours a day needs2026-09-15: no daily value, only 13 of the 18 hours a day needs2026-09-16: no daily value, only 11 of the 18 hours a day needs2026-09-17: no daily value, only 13 of the 18 hours a day needs2026-09-18: 1.5 µg/m³2026-09-19: 1.3 µg/m³2026-09-20: 2.7 µg/m³2026-09-21: no daily value, only 17 of the 18 hours a day needs2026-09-22: no daily value, only 15 of the 18 hours a day needs2026-09-23: 3.0 µg/m³2026-09-24: 4.4 µg/m³2026-09-25: no daily value, only 16 of the 18 hours a day needs2026-09-26: no daily value, only 14 of the 18 hours a day needs2026-09-27: no daily value, only 14 of the 18 hours a day needs2026-09-28: no daily value, only 10 of the 18 hours a day needs2026-09-29: no daily value, only 14 of the 18 hours a day needs2026-09-30: 3.4 µg/m³2026-10-01: no daily value, under 18 hours of readings, or readings that failed our checks2026-10-02: no daily value, no readings from the monitor2026-10-03: no daily value, no readings from the monitor2026-10-04: no daily value, only 1 of the 18 hours a day needs
0 of 98 measured days were over the WHO 24-hour guideline (15 µg/m³). 267 days without a value: 46 with no readings from the monitor, 220 with readings for part of the day (a day needs 18 hours), 1 with under 18 hours of readings or readings that failed our checks; point at a grey square for its reason (why days go blank). One row per month, one square per local day.
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

Last 4 days, hour by hour

15304 Oct 20:00 local, 2026-10-04 20:00 UTC: 2.5 µg/m³Oct 2Oct 3Oct 4Oct 5
Horta's local time; hover a bar for UTC. Dashed line: WHO 24-hour guideline (15 µg/m³).

Where it stood each day

Top 10Top 100#1#10#100#1,000#3,193NovDecJanFebMarAprMayJunJulAugSep#2,776
Its rank on each day's world board, #1 being the most polluted city that day. Higher is worse. Each gridline down is ten times the rank above it (#1, #10, #100, #1,000), so the top places get the most room.

2026 against 2025, month by month

15JanFebMar 2026: 2.5 µg/m³MarApr 2026: 2.1 µg/m³AprMay 2025: 2.5 µg/m³May 2026: 2.1 µg/m³MayJun 2026: 2.4 µg/m³JunJul 2025: 2.7 µg/m³JulAug 2025: 3.3 µg/m³AugSep 2026: 3.2 µg/m³SepOctNovDec
Faded bars: 2025. A month shows once it has 10 measured days.

Monitors

PM2.5 from 1 reference monitor, updated hourly.

StationOperatorType
FaialODC-BYEEAReference

The city's value is the median of its reference monitors each hour, when at least a third of them report (three are always enough); low-cost sensors are listed but not counted when reference monitors exist. Data via OpenAQ; licences as listed. How we rank. Embed this on your site.

Use this page

SmogRank, PM2.5 daily means, Horta, Portugal, 10 Oct 2025 – 30 Sep 2026, smogrank.com/pt/horta (accessed 5 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.

Other cities in Portugal

30-day averages, US AQI. All of Portugal.

Updated 2026-10-05 05:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.