SmogRank / Slovakia / Bratislava Region / Senec

Senec, month by month

Senec has a measured daily mean on 756 days since 11 January 2023. Its worst month was February 2025, at 74 US AQI (21.4 µg/m³), 456th of 2,633 cities on that month's world ranking. Its cleanest was April 2025, at 39 US AQI (7.1 µg/m³).

Every month since 2023

2026too few days for a mean (a year needs 199)195 days measured
JannoneFebnoneMar16 daysApr53#897May49#1,021Jun56#506Jul52#1,444Aug56#585Sep44#990Oct58#330
202554 for the year277 days measured747th of 2,681 in the world
Jan58#636Feb74#456Mar60#1,031Apr39#2,002May18 daysJun19 daysJul52#1,361Aug54#1,069Sep41#1,524Oct16 daysNov20 daysDec13 days
2024too few days for a mean (a year needs 257)232 days measured
Jan3 daysFeb58#407Mar14 daysApr19 daysMay51#935Jun57#334Jul57#402Aug15 daysSepnoneOct14 daysNov55#683Dec55#735
2023too few days for a mean (a year needs 256)52 days measured
Jan6 daysFeb67#214Mar18 daysApr3 daysMaynoneJunnoneJul1 dayAugnoneSepnoneOctnoneNovnoneDecnone
Each square is a month's mean PM2.5 in US AQI from Senec'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 Senec 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

25 months
MonthWhy
Mar 202616 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks.
Feb 2026No day measured. The others: 28 with under 18 hours of readings or readings that failed our checks.
Jan 2026No day measured. The others: 31 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.
Nov 202520 of 30 days measured; a month needs 21. The others: 10 with under 18 hours of readings or readings that failed our checks.
Oct 202516 of 31 days measured; a month needs 22. The others: 15 with under 18 hours of readings or readings that failed our checks.
Jun 202519 of 30 days measured; a month needs 21. The others: 11 with under 18 hours of readings or readings that failed our checks.
May 202518 of 31 days measured; a month needs 22. The others: 13 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 202415 of 31 days measured; a month needs 22. The others: 16 with under 18 hours of readings or readings that failed our checks.
Apr 202419 of 30 days measured; a month needs 21. The others: 11 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.
Jan 20243 of 31 days measured; a month needs 22. The others: 28 with under 18 hours of readings or readings that failed our checks.
Dec 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Nov 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Oct 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Sep 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
Aug 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Jul 20231 of 31 days measured; a month needs 22. The others: 30 with under 18 hours of readings or readings that failed our checks.
Jun 2023No day measured. The others: 30 with under 18 hours of readings or readings that failed our checks.
May 2023No day measured. The others: 31 with under 18 hours of readings or readings that failed our checks.
Apr 20233 of 30 days measured; a month needs 21. The others: 27 with under 18 hours of readings or readings that failed our checks.
Mar 202318 of 31 days measured; a month needs 22. The others: 2 missing from OpenAQ's archive, 11 with under 18 hours of readings or readings that failed our checks.
Jan 20236 of 31 days measured; a month needs 22. The others: 1 missing from OpenAQ's archive, 14 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.

Senec's worst months

MonthUS AQIDays measuredWorld rankEpisode
February 2025 7421.4 µg/m³22 of 28456thof 2,633Europe, 14 February to 1 March 2025
Europe, 1 to 14 February 2025
February 2023 6717.5 µg/m³24 of 28214thof 1,129Europe, 28 February to 4 March 2023
Europe, 6 to 25 February 2023
March 2025 6014.0 µg/m³24 of 311,031stof 2,862Europe, 14 February to 1 March 2025
February 2024 5813.1 µg/m³29 of 29407thof 2,486Europe, 27 January to 2 February 2024
January 2025 5812.8 µg/m³29 of 31636thof 2,474Germany, France and 19 more countries, January 2025
Europe, 24 December 2024 to 3 January 2025
June 2024 5712.2 µg/m³28 of 30334thof 2,563–

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.

Senec's worst days

DayUS AQIEpisode
10 Feb 2023 12645.7 µg/m³Europe, 6 to 25 February 2023
11 Feb 2023 12043.2 µg/m³Europe, 6 to 25 February 2023
24 Feb 2025 11541.1 µg/m³Europe, 14 February to 1 March 2025
1 Feb 2024 11240.0 µg/m³Europe, 27 January to 2 February 2024
31 Jan 2024 10537.0 µg/m³Europe, 27 January to 2 February 2024
5 Feb 2025 9935.0 µg/m³Europe, 1 to 14 February 2025
16 Feb 2023 9934.8 µg/m³Europe, 6 to 25 February 2023
7 Feb 2025 9934.6 µg/m³Europe, 1 to 14 February 2025
17 Jan 2025 9733.9 µg/m³Germany, France and 19 more countries, January 2025
3 Mar 2023 9532.9 µg/m³Europe, 28 February to 4 March 2023

Daily means, the highest since 11 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, Senec, Slovakia, 11 Jan 2023 – 11 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/sk/senec/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.

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

Updated 2026-10-12 18:07 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).