NO₂
Nitrogen Dioxide
What is NO₂?
Nitrogen dioxide (NO₂) is a harmful air pollutant mainly produced by road traffic, generators, and industrial activities.
What do the colours mean?
The colours on the map indicate air quality levels. They are based on measurements of nitrogen dioxide (NO₂), a common air pollutant mainly caused by traffic and burning fuels.
Health warning of emergency conditions. Everyone is more likely to be affected, and serious health effects can occur with continued exposure.
Health alert. The risk of health effects is increased for everyone, especially with longer exposure.
Some members of the general public may experience health effects.Sensitive groups are more likely to experience more serious health effects.
People who are sensitive to air pollution may experience health effects. The general public is less likely to be affected.
Air quality is acceptable. However, there may be a small health risk for people who are unusually sensitive to air pollution.
Air quality is satisfactory and air pollution poses little or no risk to health.
The colour scale ranges from Good (green) to Hazardous (dark purple). Darker colours indicate higher pollution levels and a greater potential impact on health.
WHO guidelines
The World Health Organization (WHO) provides international health-based air quality guidelines. These values indicate levels above which air pollution may harm health. They are not legally binding, but are widely used as a global health reference.
EU limit values
The European Union (EU) sets legally binding air quality limits. These limits are used to assess compliance with environmental regulations and are generally less strict than WHO guidelines.
Measured data
The values shown on this platform are measured NO₂ concentrations at specific locations. They represent average concentrations over a defined period (for example, monthly averages).
Why does this matter for health?
Long-term exposure to elevated NO₂ levels can:
- Irritate the lungs
- Worsen asthma symptoms
- Increase the risk of respiratory and cardiovascular diseases
Especially in busy urban areas.
How are these measurements taken?
NO₂ levels are measured using passive diffusion tubes placed at multiple locations across the city, including roadside, residential, and industrial areas.
