SmogRank / Ireland / Leinster / Greystones

Greystones, month by month

Greystones has a measured daily mean on 379 days since 21 May 2025. Its worst month was March 2026, at 47 US AQI (8.5 µg/m³), 2,003rd of 2,971 cities on that month's world ranking. Its cleanest was September 2026, at 24 US AQI (4.3 µg/m³).

Every month since 2025

202634 so far248 days measured2,470th of 2,793 in the world

Jan42#1,644 Feb37#2,298 Mar47#2,003 Apr36#2,046 May32#2,028Jun20 daysJul35#2,347 Aug29#2,710 Sep24#2,633 Oct20#2,607

2025too few days for a mean (a year needs 256)131 days measured

JanFebMarAprMay8 daysJun14 daysJul18 daysAug32#2,574Sep11 daysOct7 daysNov29#2,349 Dec43#1,927

Each square is a month's mean PM2.5 in US AQI from Greystones'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 Greystones 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

6 months

Month	Why
Jun 2026	20 of 30 days measured; a month needs 21. The others: 10 with under 18 hours of readings or readings that failed our checks.
Oct 2025	7 of 31 days measured; a month needs 22. The others: 24 with under 18 hours of readings or readings that failed our checks.
Sep 2025	11 of 30 days measured; a month needs 21. The others: 19 with under 18 hours of readings or readings that failed our checks.
Jul 2025	18 of 31 days measured; a month needs 22. The others: 13 with under 18 hours of readings or readings that failed our checks.
Jun 2025	14 of 30 days measured; a month needs 21. The others: 16 with under 18 hours of readings or readings that failed our checks.
May 2025	8 of 31 days measured; a month needs 22. The others: 3 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.

Greystones's worst months

Month	US AQI	Days measured	World rank	Episode
March 2026	478.5 µg/m³	28 of 31	2,003rdof 2,971	Europe, 18 to 25 March 2026
December 2025	437.7 µg/m³	22 of 31	1,927thof 3,006	–
January 2026	427.5 µg/m³	25 of 31	1,644thof 2,617	–
February 2026	376.7 µg/m³	25 of 28	2,298thof 2,866	–
April 2026	366.5 µg/m³	29 of 30	2,046thof 2,941	–
July 2026	356.3 µg/m³	30 of 31	2,347thof 2,784	–

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.

Greystones's worst days

Day	US AQI	Episode
29 May 2026	9834.4 µg/m³	–
21 Mar 2026	9130.8 µg/m³	Europe, 18 to 25 March 2026
20 Mar 2026	7522.0 µg/m³	Europe, 18 to 25 March 2026
27 Aug 2026	7119.8 µg/m³	–
15 Jul 2026	7119.6 µg/m³	–
24 Jul 2025	6918.8 µg/m³	–
4 Mar 2026	6717.6 µg/m³	–
8 Apr 2026	6315.7 µg/m³	–
23 Dec 2025	6315.6 µg/m³	–
5 Feb 2026	6315.6 µg/m³	–

Daily means, the highest since 21 May 2025; 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, Greystones, Ireland, 21 May 2025 – 11 Oct 2026. Monitor data from EEA, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/ie/greystones/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.

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

Updated 2026-10-12 22:07 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).