Sulphur Dioxide (SO₂)
A colorless gas with a sharp, irritating smell. Once a major cause of acid rain, SO2 levels have dropped dramatically in Europe but remain problematic near industrial facilities.
Regulatory Limits (µg/m³)
WHO Guideline
40
Most protective standard
EU 2030 Target
50
Directive 2024/2881
EU Current Limit
125
Being replaced in 2030
0 out of 96 tracked European cities currently exceed the EU 2030 SO₂ target.
Where Does SO₂ Come From?
- •Burning coal and oil (power generation)
- •Industrial processes (metal smelting, chemical manufacturing)
- •Shipping (heavy fuel oil)
- •Volcanic emissions
- •Petroleum refining
Health Effects of SO₂
Short-Term Exposure
- •Bronchoconstriction (airway narrowing)
- •Wheezing and shortness of breath
- •Eye and throat irritation
- •Particularly dangerous for asthmatics
Long-Term Exposure
- •Chronic bronchitis
- •Aggravation of existing cardiovascular disease
- •Contributes to particulate formation (secondary PM2.5)
- •Environmental damage (acid rain)
How to Protect Yourself
- 1.Monitor readings if you live near industrial areas or ports
- 2.Keep rescue inhalers accessible if you have asthma
- 3.Avoid outdoor exercise downwind of industrial facilities
- 4.Support clean energy transitions to reduce SO2 at source
Highest SO₂ Levels in Europe
| # | City | Country | PM2.5 | AQI |
|---|---|---|---|---|
| 1 | Plovdiv | Bulgaria | 22.5 | 23 |
| 2 | Sofia | Bulgaria | 20.0 | 20 |
| 3 | Katowice | Poland | 23.0 | 23 |
| 4 | Krakow | Poland | 22.1 | 22 |
| 5 | Lodz | Poland | 17.2 | 17 |
| 6 | Wroclaw | Poland | 16.5 | 17 |
| 7 | Warsaw | Poland | 16.2 | 16 |
| 8 | Bucharest | Romania | 18.8 | 19 |
| 9 | Poznan | Poland | 15.3 | 15 |
| 10 | Timisoara | Romania | 17.2 | 17 |
| 11 | Constanta | Romania | 17.2 | 17 |
| 12 | Gdansk | Poland | 12.4 | 12 |
| 13 | Cluj-Napoca | Romania | 13.4 | 13 |
| 14 | Thessaloniki | Greece | 16.0 | 16 |
| 15 | Athens | Greece | 14.1 | 14 |