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In the context of WHO Air Quality Guidelines, consider the following statements: 1. The 24-hour mean of PMā.ā should not exceed 15 Āµg/mĀ³ and annual mean of PMā.ā should not exceed 5 Āµg/mĀ³. 2. In a year, the highest levels of ozone pollution occur during the periods of inclement weather. 3. PMāā 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?
Explanation
The correct answer is Option 2 (1 and 4 only). This is based on the 2021 WHO Air Quality Guidelines and fundamental atmospheric chemistry.
- Statement 1 is correct: The WHO updated its Global Air Quality Guidelines in 2021, lowering the recommended limits. The annual mean for PMā.ā is now 5 Āµg/mĀ³ and the 24-hour mean is 15 Āµg/mĀ³.
- Statement 2 is incorrect: Surface-level ozone is a photochemical pollutant formed by the reaction of precursors (NOx and VOCs) in the presence of sunlight. Therefore, ozone levels peak during sunny, hot, and stagnant weather, not during "inclement" (stormy or rainy) weather.
- Statement 3 is incorrect: While PMāā can settle deep in the lungs, it is generally too large to cross the blood-air barrier. It is PMā.ā (fine particulate matter) that is capable of penetrating the lung barrier and entering the bloodstream.
- Statement 4 is correct: High concentrations of ozone are potent respiratory irritants. They can cause airway inflammation, reduce lung function, and are well-documented triggers for asthma attacks.
PROVENANCE & STUDY PATTERN
Guest previewThis is a 'Hybrid Trap': it combines a hard data memorization check (Statement 1: WHO 2021 Update) with standard static concepts (Statement 2 & 4: Ozone formation/Health). It punishes aspirants who read news headlines ('WHO updates guidelines') but failed to memorize the specific summary table.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
Web source
Presence: 5/5
"PMā.ā
, Āµg/mĀ³ Annual 35 25 15 10 5
PMā.ā
, Āµg/mĀ³ 24-hour a 75 50 37.5 25 15"
Why this source?
- This is the WHO summary table of recommended 2021 AQG levels showing both annual and 24āhour values for PM2.5.
- It lists the AQG (most stringent) levels: 5 Āµg/mĀ³ (annual) and 15 Āµg/mĀ³ (24āhour).
Web source
Presence: 5/5
"Interim targets set annual average thresholds at 5 Āµg/mĀ³ for PMā.ā
... and 24-hour averages at 15 Āµg/mĀ³ for PMā.ā
"
Why this source?
- This World Bank document cites the WHO targets and repeats the recommended AQG values.
- It explicitly states the annual PM2.5 target is 5 Āµg/mĀ³ and the 24āhour target is 15 Āµg/mĀ³.
- This is the WHO summary table of recommended 2021 AQG levels showing both annual and 24āhour values for PM2.5.
- It lists the AQG (most stringent) levels: 5 Āµg/mĀ³ (annual) and 15 Āµg/mĀ³ (24āhour).
- This World Bank document cites the WHO targets and repeats the recommended AQG values.
- It explicitly states the annual PM2.5 target is 5 Āµg/mĀ³ and the 24āhour target is 15 Āµg/mĀ³.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > c) National Air Quality Index > p. 70
Strength: 4/5
ā(c) National Air Quality Index
. National Air Quality index 'aras launched by the Prime Minister in April, 2015 starting with four cities to disseminate air quality information. The AQI has six categories of air quality, viz Good,
Satisfactory, Moderately Polluted, Poor, Very Poor and Severe. Each of these categories is associated with likely health impacts. AQI considers eight pollutants (PMro, PM 2.S, NOz, SOz, CO, O3, NH3 and Pb) for which (up to z4-hourly averaging period) National Ambient Air Quality Standards are prescribed.ā
Why relevant
States that the National Air Quality Index considers PM2.5 and refers to averaging periods 'up to 24-hourly averaging period', highlighting that PM2.5 guidelines are specified for 24āhour means.
How to extend
A student could use this to focus on WHO guideline values expressed for 24āhour averages and compare national AQI categories to WHO 24āhour limits.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > a) National Air Quality Monitoring Programme > p. 69
Strength: 4/5
ā(a) National Air Quality Monitoring Programme ā¢ e In India, the Central Pollution Control Board (CPCB) has been executing a nationwide programme of ambient air quality monitoring known as National Air Quality Monitoring Programme (NAMP) ā¢ The National Air Quality Monitoring Programme (NAMP) is undertaken in India ā¢ (i) to determine status and trends of ambient air quality; ā¢ (ii) to ascertain the compliance of NAAQS; ā¢ (iii) to identify non-attainment cities; ā¢ (iv) to understand the natural process of cleaning in the atmosphere; and ā¢ (v) to understand the impact of pollution on human health. All Rights Reserved. No part of this rDaterial ma,v be reproduced in any form or by any neans, rvithout permission in lritingā
Why relevant
Describes India's National Air Quality Monitoring Programme (NAMP) and its role in ascertaining compliance with National Ambient Air Quality Standards (NAAQS), implying the practice of comparing measured PM2.5 to defined annual and shortāterm standards.
How to extend
A student could look up WHO AQG numerical annual and 24āhour PM2.5 values to compare against national NAAQS and NAMP monitoring results.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > BS VI norms > p. 72
Strength: 3/5
āAs of April 1, 2020, the current emission standard in India mandates that all newly manufactured, sold, and registered cars in the country must adhere to the BS-VI norms.
ā¢ r BS-VI engines emit particulate matter (PM ā¤ 20 to 4a micrograms per cubic meter) within a range of 20 to 4a micrograms per cubic meter.
ā¢ r The amount of sulfur released into the atmosphere by BS-VI-compliant engines has been significantly reduced, decreasing from 5o parts per million (ppm) to just 10 ppm.ā
Why relevant
Gives numeric particulate emissions for BSāVI engines (20ā40 Āµg/m3), providing a real-world magnitude for PM concentrations used in regulatory contexts.
How to extend
A student could use these magnitudes as a baseline to judge whether WHO guideline values (annual/24āhour) are more or less stringent than typical regulatory/technical emission-related concentrations.
Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 17: Contemporary Issues > ENVIRONMENTAL DEGRADATION > p. 57
Strength: 3/5
āultraviolet B (UV-B) radiation that can increase the occurrence of some forms of skin cancer, cataracts and other diseases of eye (Fig. 17.14). Analysis by Centre for Science and Environment (CSE) reveals that the capital city is experiencing greater ozone pollution. The eight hour standard for ozone exposure is 100 micrograms per cubic meter. The levels of ozone have exceeded by 16% (122 Āµg/m3) as against 5% (106 Āµg/m3) in 2018. Delhi's hotspots have been identified as Najafgarh (92%), Sri Aurbindo Marg (87%), Narela (80%), Bawana (78%), Siri Fort (76%). (Source: T.O.I.; June 20, 2019) (iv) Air, Water, Soil, and Noise Pollution: The quality of air, water, and soil is depleting both in the urban and the rural areas.ā
Why relevant
Provides an example of an air quality standard (8āhour ozone = 100 Āµg/m3), showing that healthābased guidelines are often stated as specific Āµg/m3 limits for defined averaging times.
How to extend
A student could infer that WHO similarly states PM2.5 limits as numeric Āµg/m3 values tied to averaging periods (annual and 24āhour) and seek those specific numbers for direct comparison.
Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 29: Environment Issues and Health Effects > Note; > p. 440
Strength: 2/5
āā¢ T$PM Total Suspended Particulate Matterā¢ RPM Respirable Particulate Matterā¢ YOCs Volatite Organic Compoundsā¢ HCNYapours * Hydrogen Cyanideā
Why relevant
Lists particulate matter (TSP, RPM) as major pollutants, underlining that particulate fractions like PM2.5 are standard categories monitored and regulated.
How to extend
A student could use this to justify searching for standard guideline values specifically for PM2.5 (as a recognized pollutant fraction) expressed for annual and 24āhour means.
States that the National Air Quality Index considers PM2.5 and refers to averaging periods 'up to 24-hourly averaging period', highlighting that PM2.5 guidelines are specified for 24āhour means.
A student could use this to focus on WHO guideline values expressed for 24āhour averages and compare national AQI categories to WHO 24āhour limits.
Describes India's National Air Quality Monitoring Programme (NAMP) and its role in ascertaining compliance with National Ambient Air Quality Standards (NAAQS), implying the practice of comparing measured PM2.5 to defined annual and shortāterm standards.
A student could look up WHO AQG numerical annual and 24āhour PM2.5 values to compare against national NAAQS and NAMP monitoring results.
Gives numeric particulate emissions for BSāVI engines (20ā40 Āµg/m3), providing a real-world magnitude for PM concentrations used in regulatory contexts.
A student could use these magnitudes as a baseline to judge whether WHO guideline values (annual/24āhour) are more or less stringent than typical regulatory/technical emission-related concentrations.
Provides an example of an air quality standard (8āhour ozone = 100 Āµg/m3), showing that healthābased guidelines are often stated as specific Āµg/m3 limits for defined averaging times.
A student could infer that WHO similarly states PM2.5 limits as numeric Āµg/m3 values tied to averaging periods (annual and 24āhour) and seek those specific numbers for direct comparison.
Lists particulate matter (TSP, RPM) as major pollutants, underlining that particulate fractions like PM2.5 are standard categories monitored and regulated.
A student could use this to justify searching for standard guideline values specifically for PM2.5 (as a recognized pollutant fraction) expressed for annual and 24āhour means.
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SIMILAR QUESTIONS
In the cities of our country, which among the following atmospheric gases are normally considered in calculating the value of Air Quality Index? 1. Carbon dioxide 2. Carbon monoxide 3. Nitrogen dioxide 4. Sulfur dioxide 5. Methane Select the correct answer using the code given below.
Which one among the following has been included as a parameter for the first time under the National Ambient Air Quality Standards (NAAQS), based on Central Pollution Control Board and IIT, Kanpur research, WHO guidelines and European Union limits and practices ?
Consider the following statements : 1. Climate and Clean Air Coalition (CCAC) to Reduce Short Lived Climate Pollutants is a unique initiative of G20 group of countries. 2. The CCAC focuses on methane, black carbon and hydrofluorocarbons. Which of the statements given above is/are correct ?
Consider the following statements relating to short notice questions asked in the Legislature:
- These relate to matters of urgent public importance and can be asked for oral answer at a notice less than 10 days.
- Short notice questions can be admissible if the Minister concerned agrees to answer to it.
- Short notice questions are asked during question hour.
Which of the statements given above are correct?