In September 2021 which air quality guideline annual mean values of gaseous nitrogen dioxide was set by the WHO to protect the public from the health effects of gaseous nitrogen dioxide?

Correct option is C

In September 2021, the WHO revised its air quality guidelines, setting the annual mean limit for nitrogen dioxide (NO₂) at 10 µg/m³ to better protect public health.

Information Booster

1. Nitrogen dioxide is a major air pollutant emitted by vehicles, power plants, and industries.
2. Long-term exposure to NO₂ increases the risk of respiratory and cardiovascular diseases.
3. WHO's revised guidelines are stricter compared to the previous limit of 40 µg/m³.
4. These guidelines aim to reduce the global burden of diseases caused by air pollution.
5. Countries are urged to adopt these limits for better air quality management.

Additional Knowledge

• 20 µg/m³ (a): Previous interim target set by WHO for developing nations.
• 30 µg/m³ (b): Another interim target in earlier guidelines.
• 40 µg/m³ (d): The previous annual mean limit before revision.