Effects of SO2 in hot, humid air Moist atmospheric air at high temperature with elevated sulphur dioxide concentrations most commonly leads to which of the following outcomes?

Introduction / Context:
Sulphur dioxide (SO2) is a classic urban-industrial air pollutant. In warm, moist conditions, SO2 dissolves in surface films and condensed moisture to form acidic species that attack a wide range of materials. Understanding these material damage pathways is key for setting air quality standards and protecting sensitive infrastructure and products.

Given Data / Assumptions:

• Air contains significant SO2 and is warm and humid (e.g., summer).
• Surfaces include metals and dyed textiles exposed to ambient air.
• No specialised protective coatings are assumed.

Concept / Approach:
SO2 in moisture can form sulphurous and sulphuric acids. Acidic films corrode metals (rusting, tarnishing), soil surfaces, and attack organic dyes, leading to fading. Textiles can lose tensile strength due to acid hydrolysis of fibres, especially cellulose-based materials. Thus, multiple types of damage occur concurrently under these conditions, making “All (a), (b) and (c)” the correct choice.

Step-by-Step Solution:

Verification / Alternative check:
Materials-durability studies and pollution damage functions link SO2 exposure to corrosion rates, colour fastness loss, and mechanical property reduction in textiles.

Why Other Options Are Wrong:

• Each individual effect (a), (b), (c) does occur; limiting the answer to one misses the full impact.
• None of these: Contradicted by extensive empirical evidence.

Common Pitfalls:
Underestimating synergistic impacts of temperature and humidity, which accelerate both chemical reactions and diffusion into materials.

Final Answer:
All (a), (b) and (c).