Photochemical Smog: Health, Environmental, and Material Damage

Photochemical smog forms when NOₓ and VOCs react in sunlight to produce ozone (O₃), peroxyacetyl nitrate (PAN), aldehydes, and fine particulates.

Health Impacts

• Eye, nose, throat irritation
• Cough, wheezing, dyspnea
• Asthma/COPD exacerbations
• Increased cardiovascular events (MI, stroke)
• Premature mortality (PM₂.₅, O₃)
• Reduced lung development in children

Plant Damage

• Ozone enters stomata → oxidative stress → chlorosis, necrosis, premature senescence
• Reduced photosynthesis, growth, yield (crops, forests)
• PAN causes glazing/bronzing of leaves

Material Degradation

• Rubber cracking (ozone attacks double bonds)
• Fading of dyes, textiles, paints
• Corrosion of metals (enhanced by acidic depositions)
• Deterioration of plastics, polymers

Visibility Reduction

Fine aerosols scatter light → haze → impaired aviation, driving, scenic vistas.

Mitigation

• Reduce NOₓ/VOC emissions (vehicles, industry, solvents)
• Urban planning, public transit, EV adoption
• Air quality alerts for vulnerable populations