Which of the following conditions is least likely to be caused by long-term exposure to air pollution in urban areas?

Question

Which of the following conditions is least likely to be caused by long-term exposure to air pollution in urban areas?

1. A. Chronic bronchitis
2. B. Ischemic heart disease
3. C. Vitamin-D deficiency (Correct answer)
4. D. Asthma exacerbations

Correct Answer

Option C — Vitamin-D deficiency

Detailed Solution & Explanation

The correct answer is Vitamin-D deficiency.

Key Points

• The question asks which condition is least likely to be *caused* by long-term urban air pollution. The other three are established respiratory and cardiovascular outcomes of chronic exposure:
  • Chronic bronchitis, from sustained irritation of the airways by particulates and $\text{SO}_2$,
  • Ischemic heart disease, through the systemic inflammation and vascular effects of fine particulate matter,
  • Asthma exacerbations, triggered by $\text{PM}_{2.5}$, $\text{NO}_2$ and ozone.
• Vitamin-D deficiency is primarily a consequence of insufficient sunlight exposure, diet and skin pigmentation. It is a nutritional and lifestyle condition rather than a direct toxicological effect of polluted air.

Additional Information

• The nuance worth knowing is that heavy smog can reduce ultraviolet-B reaching the ground, so severe pollution is sometimes cited as an indirect contributor to low vitamin D. The question says *least likely to be caused by*, and an indirect, secondary pathway is still the weakest of the four.
• $\text{PM}_{2.5}$ is the pollutant of greatest health concern because particles under 2.5 micrometres penetrate deep into the alveoli and cross into the bloodstream; $\text{PM}_{10}$ is largely trapped in the upper airway.
• The WHO attributes millions of premature deaths annually to ambient and household air pollution, with ischemic heart disease and stroke — not lung disease — the largest single share.
• India's response includes the National Clean Air Programme (NCAP), launched in 2019 to cut particulate concentrations in identified non-attainment cities.