Smog from combustion of fossil fuels in cool, moist air: when water vapor condenses on smoke particles to form smog, which set of public health and visibility effects typically occurs?

Introduction / Context:
Classical sooty and sulfurous smog arises from combustion of fossil fuels, especially under cool and humid conditions that favor droplet formation around particles. Understanding the combined effects on visibility and health is essential for environmental control planning and public advisories.

Given Data / Assumptions:

• Smoke particles act as condensation nuclei for water vapor.
• Conditions: cool, moist air; often stable atmospheric layers.
• Exposure occurs at ground level in urban areas.

Concept / Approach:
Smog reduces visibility by scattering and absorbing light, leading to sky darkening. It contains irritants (e.g., sulfur oxides, acidic aerosols, fine particulates) that affect eyes and respiratory systems. Thus multiple adverse outcomes occur simultaneously, not just a single effect.

Step-by-Step Solution:

Verification / Alternative check:
Historical smog events have documented simultaneous visibility loss and health impacts, validating that multiple effects co-occur rather than in isolation.

Why Other Options Are Wrong:
Options (a), (b), and (c) each capture only part of the full impact; the comprehensive choice is the combined option.

Common Pitfalls:
Assuming smog only affects visibility; underestimating fine particle health risks; ignoring meteorological trapping that prolongs exposure.

Final Answer:
All of the above (a, b, and c)