US Air Quality Index

Current Context: As per the latest report of US Air Quality Index, Lahore is marked at most polluted cities in the world.

• As per the report, particulate matter (PM) rating of Lahore was 423.
• The second position is marked by New Delhi with PM of 229. 
• The third position is marked by Kathmandu with PM of 178. 
• As per the United States Environmental Protection Agency, if the value of AQI (Air Quality Index) is under 50, then the air quality is determined to be satisfactory. 

Question: 

Q.1 Which city topped and is marked as most polluted cities in the world as per the latest report of US Air Quality Index?
a. Lahore
b. Kathmandu
c. New Delhi
d. Karachi