Q44. In the context of WHO Air Quality Guidelines, consider the following statements:
- The 24-hour mean of PM2.5 should not exceed 15 ug/m³ and the annual mean of PM2.5 should not exceed 5 µg/m³.
- In a year, the highest levels of ozone pollution occur during periods of inclement weather.
- PM10 can penetrate the lung barrier and enter the bloodstream.
- Excessive ozone in the air can trigger asthma.
Which of the statements given above are correct?
a) 1, 3 and 4
b) 1 and 4 only
c) 2, 3 and 4
d) 1 and 2 only
Answer – B
- Statement 1 is correct: WHO’s new guidelines recommend air quality levels for six pollutants — particulate matter (PM), ozone (O₃), nitrogen dioxide (NO₂) sulfur dioxide (SO₂), and carbon monoxide (CO) — that are not just health hazards but they also give rise to other damaging pollutants. The recommendation for PM 2.5 is that the annual average should not exceed 5 micrograms per cubic meter or 15 micrograms per cubic meter in a day.
- Statement 2 is not correct: Ozone is one of the main components of photochemical smog at ground level. It is created when pollutants like nitrogen oxides (NOx) from industry and car emissions and volatile organic compounds (VOCs) from vehicles, solvents, and industry react with sunlight (photochemical reaction). Ozone levels are typically highest during the afternoon hours of the summer months when the. influence of direct sunlight is the greatest. Inclement weather is unpleasant, especially with cold wind and rain. So, Ozone pollution will be low during inclement weather.
- Statement 3 is not correct: While particles with a diameter of 10 millimeters or less, or PM10, can enter and lodge deep inside the lungs, particles with a diameter of 2.5 microns or less, or PM2.5, are much more harmful to human health. The lung barrier is permeable, and PM2.5 can get into the bloodstream.
- Statement 4 is correct: The health of people can be significantly impacted by excessive ozone in the air. Breathing issues, asthma attacks, lowered lung function and lung illnesses can all be brought on by it.
For UPSC Prelims Resources, Click here
For Daily Updates and Study Material:
Join our Telegram Channel – Edukemy for IAS
- 1. Learn through Videos – here
- 2. Be Exam Ready by Practicing Daily MCQs – here
- 3. Daily Newsletter – Get all your Current Affairs Covered – here
- 4. Mains Answer Writing Practice – here
Visit our YouTube Channel – here
