SmogRank / Romania / Cluj County

Air quality in Dej

Cluj County, Romania. PM2.5 from 2 reference monitors, updated hourly.

12.0 µg/m³
Moderate

Mean for 30 Sept, the most recent day with readings, 0.8× the WHO 24-hour guideline. No hourly readings have reached us since; some networks publish days late.

Rank

24 h
–
not enough data
7 days
#381
of 2,333 · 11.7 µg/m³
30 days
#452
of 2,331 · 9.3 µg/m³
Year
#203
of 2,173 · 23.0 µg/m³

Why it ranks here

Seasonal. Over the past year its worst months were January, averaging up to 82.3 µg/m³ against 8.6 in its cleanest month. Seasonal peaks usually come from heating, crop burning, fire or dust seasons.

Based on Dej's own measurements; causes are the usual kinds for a pattern like this, not a confirmed source.

Hour by hour

No hourly readings in the last few days. The chart returns when the monitors' data arrives.

Every day for a year

SepNovDecJanFebMarAprMayJunJulAugSepMonWedFri2025-09-29: 11.5 µg/m³2025-09-30: no data2025-10-01: no data2025-10-02: no data2025-10-03: 8.4 µg/m³2025-10-04: 7.4 µg/m³2025-10-05: 11.2 µg/m³2025-10-06: no data2025-10-07: no data2025-10-08: 10.0 µg/m³2025-10-09: 15.3 µg/m³2025-10-10: 12.9 µg/m³2025-10-11: 6.6 µg/m³2025-10-12: 5.8 µg/m³2025-10-13: 8.0 µg/m³2025-10-14: 12.8 µg/m³2025-10-15: no data2025-10-16: no data2025-10-17: no data2025-10-18: 24.6 µg/m³2025-10-19: 9.2 µg/m³2025-10-20: 19.0 µg/m³2025-10-21: 26.5 µg/m³2025-10-22: 38.1 µg/m³2025-10-23: 28.3 µg/m³2025-10-24: 13.1 µg/m³2025-10-25: 12.4 µg/m³2025-10-26: 14.6 µg/m³2025-10-27: 14.6 µg/m³2025-10-28: 25.4 µg/m³2025-10-29: 17.5 µg/m³2025-10-30: 28.7 µg/m³2025-10-31: 38.3 µg/m³2025-11-01: 29.9 µg/m³2025-11-02: 30.1 µg/m³2025-11-03: 26.6 µg/m³2025-11-04: 13.3 µg/m³2025-11-05: 36.2 µg/m³2025-11-06: no data2025-11-07: no data2025-11-08: 48.0 µg/m³2025-11-09: 27.9 µg/m³2025-11-10: 17.1 µg/m³2025-11-11: 16.5 µg/m³2025-11-12: 21.3 µg/m³2025-11-13: 35.3 µg/m³2025-11-14: no data2025-11-15: no data2025-11-16: no data2025-11-17: no data2025-11-18: no data2025-11-19: no data2025-11-20: no data2025-11-21: no data2025-11-22: 17.4 µg/m³2025-11-23: 5.2 µg/m³2025-11-24: no data2025-11-25: 19.1 µg/m³2025-11-26: no data2025-11-27: 10.8 µg/m³2025-11-28: no data2025-11-29: no data2025-11-30: no data2025-12-01: no data2025-12-02: no data2025-12-03: 22.3 µg/m³2025-12-04: 31.3 µg/m³2025-12-05: 20.7 µg/m³2025-12-06: 43.4 µg/m³2025-12-07: 45.5 µg/m³2025-12-08: 42.6 µg/m³2025-12-09: no data2025-12-10: 53.0 µg/m³2025-12-11: 34.6 µg/m³2025-12-12: 11.1 µg/m³2025-12-13: 12.5 µg/m³2025-12-14: 15.3 µg/m³2025-12-15: 22.3 µg/m³2025-12-16: 64.7 µg/m³2025-12-17: 82.4 µg/m³2025-12-18: no data2025-12-19: no data2025-12-20: 47.9 µg/m³2025-12-21: 62.7 µg/m³2025-12-22: 27.5 µg/m³2025-12-23: 16.1 µg/m³2025-12-24: 15.2 µg/m³2025-12-25: 20.6 µg/m³2025-12-26: 31.7 µg/m³2025-12-27: no data2025-12-28: 12.1 µg/m³2025-12-29: 14.6 µg/m³2025-12-30: 21.8 µg/m³2025-12-31: 11.8 µg/m³2026-01-01: no data2026-01-02: 39.6 µg/m³2026-01-03: 45.3 µg/m³2026-01-04: no data2026-01-05: 55.3 µg/m³2026-01-06: 44.9 µg/m³2026-01-07: no data2026-01-08: no data2026-01-09: no data2026-01-10: 45.1 µg/m³2026-01-11: no data2026-01-12: 70.0 µg/m³2026-01-13: 60.6 µg/m³2026-01-14: 59.6 µg/m³2026-01-15: 52.7 µg/m³2026-01-16: no data2026-01-17: no data2026-01-18: 126.5 µg/m³2026-01-19: no data2026-01-20: 152.0 µg/m³2026-01-21: 162.0 µg/m³2026-01-22: 167.0 µg/m³2026-01-23: 135.5 µg/m³2026-01-24: 116.0 µg/m³2026-01-25: 98.1 µg/m³2026-01-26: 65.0 µg/m³2026-01-27: 66.8 µg/m³2026-01-28: 43.2 µg/m³2026-01-29: 68.4 µg/m³2026-01-30: 95.1 µg/m³2026-01-31: 42.4 µg/m³2026-02-01: 31.4 µg/m³2026-02-02: 24.9 µg/m³2026-02-03: 28.4 µg/m³2026-02-04: 47.5 µg/m³2026-02-05: no data2026-02-06: 29.0 µg/m³2026-02-07: 38.1 µg/m³2026-02-08: 19.2 µg/m³2026-02-09: 14.6 µg/m³2026-02-10: 14.3 µg/m³2026-02-11: no data2026-02-12: 29.7 µg/m³2026-02-13: 30.7 µg/m³2026-02-14: 33.1 µg/m³2026-02-15: 25.0 µg/m³2026-02-16: 20.1 µg/m³2026-02-17: 26.5 µg/m³2026-02-18: 23.1 µg/m³2026-02-19: no data2026-02-20: no data2026-02-21: 14.0 µg/m³2026-02-22: 22.5 µg/m³2026-02-23: 23.4 µg/m³2026-02-24: 18.5 µg/m³2026-02-25: 8.1 µg/m³2026-02-26: 23.8 µg/m³2026-02-27: 45.1 µg/m³2026-02-28: 52.4 µg/m³2026-03-01: 53.2 µg/m³2026-03-02: 59.8 µg/m³2026-03-03: 55.4 µg/m³2026-03-04: 47.0 µg/m³2026-03-05: 40.7 µg/m³2026-03-06: 28.1 µg/m³2026-03-07: 42.9 µg/m³2026-03-08: 39.8 µg/m³2026-03-09: 29.7 µg/m³2026-03-10: 27.9 µg/m³2026-03-11: 33.1 µg/m³2026-03-12: 43.0 µg/m³2026-03-13: no data2026-03-14: no data2026-03-15: no data2026-03-16: no data2026-03-17: 43.1 µg/m³2026-03-18: 23.4 µg/m³2026-03-19: 17.0 µg/m³2026-03-20: 23.4 µg/m³2026-03-21: 23.7 µg/m³2026-03-22: 19.4 µg/m³2026-03-23: 24.6 µg/m³2026-03-24: 26.3 µg/m³2026-03-25: 32.8 µg/m³2026-03-26: 28.4 µg/m³2026-03-27: 17.7 µg/m³2026-03-28: no data2026-03-29: no data2026-03-30: no data2026-03-31: 11.8 µg/m³2026-04-01: no data2026-04-02: 20.4 µg/m³2026-04-03: 27.5 µg/m³2026-04-04: 20.6 µg/m³2026-04-05: 23.6 µg/m³2026-04-06: 16.6 µg/m³2026-04-07: 6.7 µg/m³2026-04-08: 5.3 µg/m³2026-04-09: no data2026-04-10: 22.2 µg/m³2026-04-11: 21.6 µg/m³2026-04-12: no data2026-04-13: 21.6 µg/m³2026-04-14: 11.3 µg/m³2026-04-15: 18.0 µg/m³2026-04-16: no data2026-04-17: 16.4 µg/m³2026-04-18: 10.5 µg/m³2026-04-19: no data2026-04-20: 14.7 µg/m³2026-04-21: no data2026-04-22: 10.3 µg/m³2026-04-23: 10.8 µg/m³2026-04-24: 8.1 µg/m³2026-04-25: 15.8 µg/m³2026-04-26: 10.3 µg/m³2026-04-27: 6.9 µg/m³2026-04-28: 12.0 µg/m³2026-04-29: 9.7 µg/m³2026-04-30: 7.7 µg/m³2026-05-01: 9.9 µg/m³2026-05-02: 9.7 µg/m³2026-05-03: 13.6 µg/m³2026-05-04: no data2026-05-05: 9.9 µg/m³2026-05-06: 10.9 µg/m³2026-05-07: 13.4 µg/m³2026-05-08: 7.3 µg/m³2026-05-09: no data2026-05-10: 7.7 µg/m³2026-05-11: no data2026-05-12: 7.0 µg/m³2026-05-13: 6.0 µg/m³2026-05-14: 8.3 µg/m³2026-05-15: 8.6 µg/m³2026-05-16: 9.5 µg/m³2026-05-17: 7.3 µg/m³2026-05-18: 7.7 µg/m³2026-05-19: no data2026-05-20: 9.4 µg/m³2026-05-21: 11.1 µg/m³2026-05-22: 8.5 µg/m³2026-05-23: 7.6 µg/m³2026-05-24: no data2026-05-25: no data2026-05-26: no data2026-05-27: 9.3 µg/m³2026-05-28: no data2026-05-29: 3.9 µg/m³2026-05-30: 5.6 µg/m³2026-05-31: 5.7 µg/m³2026-06-01: 8.0 µg/m³2026-06-02: 6.8 µg/m³2026-06-03: 8.9 µg/m³2026-06-04: no data2026-06-05: no data2026-06-06: 8.4 µg/m³2026-06-07: 6.5 µg/m³2026-06-08: no data2026-06-09: no data2026-06-10: no data2026-06-11: no data2026-06-12: no data2026-06-13: no data2026-06-14: 5.9 µg/m³2026-06-15: no data2026-06-16: no data2026-06-17: 9.1 µg/m³2026-06-18: 8.2 µg/m³2026-06-19: no data2026-06-20: 11.7 µg/m³2026-06-21: no data2026-06-22: no data2026-06-23: no data2026-06-24: 11.6 µg/m³2026-06-25: 11.8 µg/m³2026-06-26: 11.5 µg/m³2026-06-27: 13.8 µg/m³2026-06-28: no data2026-06-29: no data2026-06-30: 20.6 µg/m³2026-07-01: 16.7 µg/m³2026-07-02: 15.2 µg/m³2026-07-03: 9.4 µg/m³2026-07-04: no data2026-07-05: 6.9 µg/m³2026-07-06: 7.6 µg/m³2026-07-07: 8.7 µg/m³2026-07-08: 8.7 µg/m³2026-07-09: 6.4 µg/m³2026-07-10: 7.4 µg/m³2026-07-11: 7.0 µg/m³2026-07-12: 7.8 µg/m³2026-07-13: 6.9 µg/m³2026-07-14: 8.6 µg/m³2026-07-15: 10.2 µg/m³2026-07-16: no data2026-07-17: no data2026-07-18: 13.2 µg/m³2026-07-19: 11.5 µg/m³2026-07-20: no data2026-07-21: no data2026-07-22: 8.8 µg/m³2026-07-23: 7.2 µg/m³2026-07-24: 6.3 µg/m³2026-07-25: 4.9 µg/m³2026-07-26: 6.6 µg/m³2026-07-27: no data2026-07-28: 5.8 µg/m³2026-07-29: 7.5 µg/m³2026-07-30: 8.4 µg/m³2026-07-31: 9.2 µg/m³2026-08-01: 10.8 µg/m³2026-08-02: no data2026-08-03: no data2026-08-04: no data2026-08-05: 14.0 µg/m³2026-08-06: 15.8 µg/m³2026-08-07: 10.1 µg/m³2026-08-08: 10.7 µg/m³2026-08-09: no data2026-08-10: 8.9 µg/m³2026-08-11: 10.7 µg/m³2026-08-12: 11.9 µg/m³2026-08-13: 8.9 µg/m³2026-08-14: 7.1 µg/m³2026-08-15: no data2026-08-16: no data2026-08-17: 11.8 µg/m³2026-08-18: no data2026-08-19: 7.2 µg/m³2026-08-20: 8.6 µg/m³2026-08-21: 14.7 µg/m³2026-08-22: 12.3 µg/m³2026-08-23: no data2026-08-24: 5.4 µg/m³2026-08-25: 7.7 µg/m³2026-08-26: 10.5 µg/m³2026-08-27: no data2026-08-28: no data2026-08-29: 9.1 µg/m³2026-08-30: no data2026-08-31: 9.1 µg/m³2026-09-01: 9.6 µg/m³2026-09-02: no data2026-09-03: 6.2 µg/m³2026-09-04: 7.0 µg/m³2026-09-05: 7.8 µg/m³2026-09-06: no data2026-09-07: 4.9 µg/m³2026-09-08: no data2026-09-09: 7.4 µg/m³2026-09-10: 9.7 µg/m³2026-09-11: 9.8 µg/m³2026-09-12: 7.1 µg/m³2026-09-13: no data2026-09-14: no data2026-09-15: 8.7 µg/m³2026-09-16: 9.1 µg/m³2026-09-17: no data2026-09-18: 14.9 µg/m³2026-09-19: 10.9 µg/m³2026-09-20: no data2026-09-21: 6.5 µg/m³2026-09-22: 4.3 µg/m³2026-09-23: 7.7 µg/m³2026-09-24: 8.9 µg/m³2026-09-25: 12.8 µg/m³2026-09-26: 11.0 µg/m³2026-09-27: 13.3 µg/m³2026-09-28: 11.5 µg/m³2026-09-29: 12.5 µg/m³2026-09-30: 12.0 µg/m³
Good 0–9.0Moderate 9.1+Unhealthy for sensitive groups 35.5+Unhealthy 55.5+Very unhealthy 125.5+Hazardous 225.5+No data

122 of 263 measured days were over the WHO 24-hour guideline.

Daily world rank

#1#1935NovDecJanFebMarAprMayJunJulAugSep

Rank on each day's board (1 = most polluted city that day).

2026 against 2025, month by month

15Jan 2025: 46.1 µg/m³Jan 2026: 82.3 µg/m³JanFeb 2025: 52.6 µg/m³Feb 2026: 26.8 µg/m³FebMar 2025: 33.1 µg/m³Mar 2026: 33.0 µg/m³MarApr 2025: 12.5 µg/m³Apr 2026: 14.5 µg/m³AprMay 2025: 7.8 µg/m³May 2026: 8.6 µg/m³MayJun 2025: 9.4 µg/m³Jun 2026: 10.2 µg/m³JunJul 2025: 8.2 µg/m³Jul 2026: 8.7 µg/m³JulAug 2025: 9.2 µg/m³Aug 2026: 10.3 µg/m³AugSep 2025: 9.7 µg/m³Sep 2026: 9.3 µg/m³SepOct 2025: 17.0 µg/m³OctNov 2025: 23.6 µg/m³NovDec 2025: 31.3 µg/m³Dec

Faded bars: 2025. A month shows once it has 10 measured days.

This week against past years

This weekThis week: 11.7 µg/m³11.720252025: 9.7 µg/m³9.72024no data2023no data

Mean PM2.5 for 24 Sept to 30 Sept in each year. Dashed line: WHO 24-hour guideline.

Monitors

StationOperatorType
CJ-5ODC-BYEEAReference
CJ-5ODC-BYEEAReference

The city's value is the median of its reference monitors each hour; 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.

Other cities in Romania

Suceava 14.2Târgu Mureş 13.1Calafat 10.0Sighetu Marmaţiei 9.5Popeşti-Leordeni 9.4Craiova 9.4Iaşi 9.3Târgu Jiu 9.1Buftea 8.5Voluntari 8.2Bucharest 7.9Braşov 7.9

30-day averages, µg/m³. All of Romania →

Updated 2026-10-01 10:07 UTC. Values are PM2.5 in µg/m³ (fine particles), the median of each city's monitors.