In the context of WHO Air Quality Guidelines, consider the following statements: 1. The 24-hour mean of PM₂.₅ 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?

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 24‑hour means.

A student could use this to focus on WHO guideline values expressed for 24‑hour averages and compare national AQI categories to WHO 24‑hour 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 short‑term standards.

A student could look up WHO AQG numerical annual and 24‑hour PM2.5 values to compare against national NAAQS and NAMP monitoring results.

Gives numeric particulate emissions for BS‑VI engines (20–40 µg/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/24‑hour) are more or less stringent than typical regulatory/technical emission-related concentrations.

Provides an example of an air quality standard (8‑hour ozone = 100 µg/m3), showing that health‑based guidelines are often stated as specific µg/m3 limits for defined averaging times.

A student could infer that WHO similarly states PM2.5 limits as numeric µg/m3 values tied to averaging periods (annual and 24‑hour) 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 24‑hour means.

Explains that ground‑level ozone is formed by reactions involving hydrocarbons, nitrogen oxides, heat and sunlight, and contrasts this with winter stagnation of other pollutants under low wind and fog.

A student could combine this rule with the basic fact that inclement weather often brings reduced sunlight and cooler temperatures to infer that ozone peaks are less likely during such periods.

States vehicles and industries emit precursors (NOx, hydrocarbons) and that ozone at ground level is produced (and is a pollutant) — implicitly linking ozone formation to emissions plus atmospheric conditions.

Using typical meteorological knowledge (sunlight-driven photochemistry), a student could infer that sunny, warm, stagnant conditions favor higher ozone rather than inclement (cloudy/rainy) weather.

Provides measured examples of high ground‑level ozone concentrations in urban 'hotspots' and refers to an 8‑hour exposure standard, implying ozone has measurable seasonal/spatial patterns.

A student could compare known seasonal weather patterns of such urban hotspots (e.g., hotter, sunnier months) against pollution records to judge whether peaks align with inclement weather or with fair, warm conditions.

Describes clear seasonal variation of stratospheric ozone (lowest in October) showing that ozone concentrations can follow seasonal cycles.

While this concerns stratospheric ozone, a student could use the general idea that ozone levels vary seasonally and therefore seek seasonal ground‑level ozone data to test whether peaks coincide with inclement weather.

States that the finer suspended particles, when breathed in, can lodge in our lungs and cause lung damage.

A student could combine this with the fact that 'lodging in lungs' implies reach to deep airways and then ask whether particles small enough to lodge might cross into blood vessels.

Explains that alveoli are the lung structures providing the surface where gas exchange occurs (i.e., close contact between air and blood).

A student could use this physiology fact to reason that any particle reaching alveoli could be spatially close enough to capillaries to potentially translocate into the bloodstream, and then seek literature on particle translocation across the alveolar–capillary barrier.

Lists abbreviations including 'RPM Respirable Particulate Matter', implying some particulate fractions are classified by their ability to be inhaled deeply.

A student could use the concept of 'respirable' size classes (e.g., PM10, PM2.5) from standard outside knowledge to ask whether respirable fractions are small enough to reach alveoli and possibly cross into blood.

Describes pneumoconiosis caused by deposit of coal dust in the lungs, an example of particle deposition leading to serious lung disease.

A student could generalize that some inhaled particles deposit and interact with lung tissue, then investigate which particle sizes deposit where and whether deposited particles can translocate to blood.

Notes that small infectious particles (example: SARS‑CoV‑2) can get through the lungs, indicating that very small agents can bypass some lung defenses.

A student could analogize that if viral particles can reach or penetrate lung barriers, similarly small PM fractions might; this would motivate checking WHO/medical sources on particulate translocation.