Q44.
In the context of WHO Air Quality Guidelines, consider the following statements: 1. The 24-hour mean of PM 2.5 should not exceed 15 µg/m3 and annual mean of PM2.5 should not exceed 5 µg/m3. 2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather. 3. PM10 can penetrate the lung barrier and enter the bloodstream. 4. Excessive ozone in the air can trigger asthma. Which of the statements given above are correct?
Answer
B
Explanation
Statement 1 is correct: According to WHO guidelines, the annual average for PM2.5 should not exceed 5 micrograms per cubic metre, and the 24-hour average should not exceed 15 micrograms per cubic metre. Statement 2 is incorrect: Highest levels of ozone pollution occur during periods of SUNNY weather (not inclement weather), as ozone is formed by photochemical reactions with sunlight. Statement 3 is incorrect: PM2.5 (not PM10) can penetrate the lung barrier and enter the bloodstream. PM10 can penetrate deep into lungs but PM2.5 goes further to enter blood. Statement 4 is correct: Excessive ozone can cause breathing problems, trigger asthma, and reduce lung function.