Detailed Explanation:

Answer: Option 1 — 1, 2 and 3 only

Benzene is a colorless, volatile organic compound and a known carcinogen present in the environment through various natural and anthropogenic sources. The main sources of benzene exposure include automobile exhaust (as benzene is present in petrol), tobacco smoke (both active and passive), and wood burning (due to incomplete combustion). Varnished wooden furniture and polyurethane products are not significant sources of benzene pollution.

✅ Statement 1 – Correct: Automobile exhaust, especially from petrol-driven vehicles, is a major source of benzene as it is a component of petroleum products.
✅ Statement 2 – Correct: Tobacco smoke contains benzene and is a significant source of exposure for both smokers and passive smokers.
✅ Statement 3 – Correct: Wood burning releases benzene through incomplete combustion, along with other pollutants like polycyclic aromatic hydrocarbons (PAHs).
❌ Statement 4 – Incorrect: Varnished wooden furniture may emit benzene during application but once cured, it is not a significant source of benzene pollution.
❌ Statement 5 – Incorrect: Polyurethane products are primarily associated with other volatile organic compounds (VOCs), not benzene.

📝 Short Notes: Benzene Pollution

• Nature: Benzene (C₆H₆) is a colorless, highly flammable liquid with a sweet odor, classified as a Group 1 carcinogen by IARC.
• Major Sources: Automobile emissions (petrol combustion), tobacco smoke, industrial processes, petroleum refineries, and incomplete combustion of organic materials (wood, coal).
• Health Effects: Prolonged exposure causes blood disorders, anemia, leukemia, immune system suppression, and reproductive health issues.
• Indoor Sources: Tobacco smoke, attached garages (vehicle emissions), and certain paints/solvents during application.
• Occupational Exposure: Workers in petroleum refineries, chemical plants, rubber manufacturing, and printing industries face higher risks.
• Regulatory Standards: WHO air quality guideline for benzene is minimal (no safe level); ambient air standards vary by country to limit exposure.