SmogRank / United States / Delaware / Dover
Dover, month by month
Dover has a measured daily mean on 1,270 days since 1 January 2023. Its worst month was June 2023, at 78 US AQI (23.8 µg/m³), 199th of 1,603 cities on that month's world ranking. Its cleanest was October 2025, at 22 US AQI (3.9 µg/m³). 2025 averaged 39 US AQI (7.0 µg/m³), against 36 US AQI (6.5 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 |
|---|---|
| Oct 2026 | 4 of 11 days measured; a month needs 8. The others: 6 with no readings from the monitor, 1 with readings for part of the day (a day needs 18 hours). |
| May 2026 | 19 of 31 days measured; a month needs 22. The others: 12 with under 18 hours of readings or readings that failed our checks. |
| Apr 2026 | 1 of 30 days measured; a month needs 21. The others: 29 with under 18 hours of readings or readings that failed our checks. |
| Nov 2025 | 17 of 30 days measured; a month needs 21. The others: 13 with under 18 hours of readings or readings that failed our checks. |
| Nov 2023 | 16 of 30 days measured; a month needs 21. The others: 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.
Dover's worst months
| Month | US AQI | World rank | Episode |
|---|---|---|---|
| June 2023 | 7823.8 µg/m³ | 199thof 1,603 | Eastern United States and Canada, June and July 2023 Eastern United States and Canada, May and June 2023 |
| July 2026 | 6516.7 µg/m³ | 435thof 2,784 | Northern United States and Canada, July 2026 |
| June 2025 | 5410.7 µg/m³ | 1,091stof 2,508 | Northern United States and Canada, June 2025 |
| February 2026 | 5410.7 µg/m³ | 1,253rdof 2,866 | – |
| July 2023 | 5310.4 µg/m³ | 619thof 1,432 | Eastern United States and Canada, June and July 2023 |
| July 2025 | 529.7 µg/m³ | 1,338thof 2,889 | – |
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.
Dover's worst days
| Day | US AQI | Episode |
|---|---|---|
| 17 Jul 2026 | 210135.0 µg/m³ | Northern United States and Canada, July 2026 |
| 8 Jun 2023 | 207132.0 µg/m³ | Eastern United States and Canada, May and June 2023 |
| 7 Jun 2023 | 186106.0 µg/m³ | Eastern United States and Canada, May and June 2023 |
| 29 Jun 2023 | 16068.9 µg/m³ | Eastern United States and Canada, June and July 2023 |
| 16 Jul 2026 | 15358.7 µg/m³ | Northern United States and Canada, July 2026 |
| 18 Jul 2026 | 14252.2 µg/m³ | Northern United States and Canada, July 2026 |
| 14 Jun 2025 | 12344.5 µg/m³ | Northern United States and Canada, June 2025 |
| 30 Jun 2023 | 12043.4 µg/m³ | Eastern United States and Canada, June and July 2023 |
| 1 Jun 2023 | 10537.0 µg/m³ | Eastern United States and Canada, May and June 2023 |
| 9 Jun 2023 | 9231.0 µg/m³ | Eastern United States and Canada, May and June 2023 |
Daily means, the highest since 1 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, Dover, United States, 1 Jan 2023 – 4 Oct 2026. Monitor data from AirNow, via OpenAQ and from the publisher directly; sources listed at smogrank.com/sources. smogrank.com/us/dover/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.
Dover now: the last 24 hours, its ranks today and the last 12 months day by day.
Updated 2026-10-12 17:07 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).