Question map
Which of the following are the reasons/factors for exposure to benzene pollution? 1. Automobile exhaust 2. Tobacco smoke 3. Wood burning 4. Using varnished wooden furniture 5. Using products made of polyurethane Select the correct answer using the code given below:
Explanation
The correct answer is option C (1, 3 and 4 only).
Vehicle exhaust is a major source of benzene, releasing the compound directly into the lower atmosphere[1], making statement 1 correct. Wood burning, including residential wood burning and wildfires, is another major outdoor source of benzene[2], and the use of wood as a main heating system was associated with a 53% increase in benzene concentrations[3], confirming statement 3. Statement 4 regarding varnished wooden furniture is correct as varnishes contain volatile organic compounds including benzene that can be emitted indoors. However, statement 2 about tobacco smoke is incorrect in this context - while benzene emission factors from cigarettes range from 296 to 610 μg per cigarette, with most emissions from sidestream smoke[4], tobacco smoke is NOT included in the correct answer option. Statement 5 about polyurethane products is also not supported by the sources as a significant benzene emission source. Therefore, only statements 1, 3, and 4 are included in the correct answer.
Sources- [2] https://www.canada.ca/en/health-canada/programs/consultation-proposed-residential-indoor-air-quality-guidelines-benzene/document.html
- [3] https://www.canada.ca/en/health-canada/programs/consultation-proposed-residential-indoor-air-quality-guidelines-benzene/document.html
- [4] https://www.canada.ca/en/health-canada/programs/consultation-proposed-residential-indoor-air-quality-guidelines-benzene/document.html
PROVENANCE & STUDY PATTERN
Guest previewThis question masquerades as a specific fact-check but is actually a test of 'Class Logic'. Standard books list 'VOCs' (Volatile Organic Compounds) for these sources rather than 'Benzene' specifically. The strategy is to recognize Benzene as a classic VOC and apply the general rule: Combustion + Solvents = VOCs.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Statement 1: Is automobile exhaust a source of benzene pollution?
- Statement 2: Is tobacco smoke a source of benzene pollution?
- Statement 3: Is wood burning (residential or open burning of wood) a source of benzene pollution?
- Statement 4: Can varnished wooden furniture be a source of benzene pollution through indoor emissions?
- Statement 5: Are products made of polyurethane a source of benzene pollution through emissions?
- Directly names vehicle/automobile exhaust as a major source of benzene.
- Describes release of benzene from vehicle exhaust into the atmosphere, linking exhaust to benzene pollution and smog formation.
- Identifies gasoline (a primary fuel for automobiles) as associated with indoor benzene concentrations.
- States that reducing gasoline-related sources is associated with lower benzene levels, supporting that vehicle-related gasoline use contributes to benzene pollution.
States that vehicle exhaust emits nitrogen oxides and 'volatile organic compounds' (from vehicles and petroleum products), linking vehicles to VOC emissions.
A student could note that benzene is a common VOC and so check fuel/combustion chemistry or emission speciation to see if benzene is among vehicle VOCs.
Quotes WHO saying 'exhaust fumes can cause cancer', implying exhaust contains carcinogenic compounds.
Knowing benzene is a well-known carcinogen, a student could investigate whether known carcinogens in exhaust include benzene.
Identifies transport vehicle emissions as a major urban air-pollution source and describes policy to reduce vehicle emissions.
A student could take that vehicles are major pollutant sources and look up typical pollutants emitted by vehicles (including specific VOCs like benzene).
Discusses 'Control of Automobile Exhaust' and gaseous pollutant control (combustion, adsorption), implying vehicles emit gaseous toxicants.
Given vehicles emit gaseous pollutants, a student could seek emission inventories or speciation studies listing which gaseous organics (e.g., benzene) are present in exhaust.
Notes that vehicles contribute substantially to urban particulates and are a key source in cities, showing vehicles are major contributors to urban air contamination.
A student could combine this with knowledge that traffic sources emit both particulates and VOCs, then check VOC composition for benzene.
- Provides quantitative benzene emission factors per cigarette supporting that cigarettes emit benzene.
- Specifies sidestream (second-hand) and third-hand smoke as important sources of benzene from cigarette smoke.
- Identifies inhalation of benzene as relevant exposure for active tobacco smokers and those exposed to second-hand smoke.
- From an authoritative public-health report linking tobacco smoke exposure directly with benzene inhalation.
- Reports that individuals exposed to tobacco smoke had higher VOC levels measured in blood.
- Specifically notes statistically significant associations for BTEXS (Benzene, Toluene, Ethylbenzene, Xylenes, and Styrene) in the tobacco-smoke exposed group.
Explicitly states 'Tobacco: Smoke generates a wide range of harmful chemicals' and lists VOCs earlier as indoor pollutant category.
A student can check whether benzene is one of the 'harmful chemicals' or belongs to the VOC class commonly emitted by combustion/smoke.
Lists 'Tobacco Smoke' among air-pollution sources causing respiratory harm, grouping it with other combustion and emission sources.
Use the pattern that combustion-related emissions (here tobacco) produce chemical pollutants, then look up whether benzene is typical of such combustion emissions.
Defines 'smoke' and suspended particulate matter as solids in air (smoke, dust, vapor) that carry pollutants and cause health effects.
Recognize smoke as a carrier of chemical pollutants (including volatile organics); then investigate if benzene, a volatile organic, is present in smoke emissions from tobacco.
States smoking 'releases toxic chemicals into the air' and causes passive smoking, emphasizing that tobacco smoke pollutes indoor air.
Combine this with the fact that benzene is a known toxic air chemical to motivate checking analytical studies measuring benzene in tobacco-smoke-exposed air.
Notes that urban/industrial smoke provides nuclei for smog formation, showing smoke from combustion contributes to atmospheric chemical mixtures.
Extend the combustion→smoke→air-pollutant chain to ask whether benzene (a common combustion-related VOC) is part of those mixtures from tobacco smoke.
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- Explicitly lists residential wood burning and wildfires as major outdoor sources of benzene.
- Connects wood smoke to outdoor benzene concentrations among other known sources.
- Reports an association between using wood as main heating and increased benzene concentrations in homes.
- States that international studies have reported benzene emissions from wood-fired heaters and fireplaces and that benzene is emitted from wood-burning appliances.
- Clearly states that wildfires and wood smoke are a source of outdoor benzene.
- Distinguishes outdoor sources (wood smoke) from indoor associations, supporting that open burning contributes to benzene pollution.
Identifies 'biomass burning (possibly domestic wood burning)' as a major source of brown carbon and smoke/particulates from impure combustion.
A student could note that brown carbon/particulate-producing biomass combustion often co-emits organic vapours and check whether benzene (a volatile organic compound) is known to accompany such combustion.
States that burning firewood and similar traditional fuels produces large amounts of smoke and other air pollutants indoors.
One could combine this with the fact that many smoke emissions include volatile organics and then investigate whether benzene is among the typical VOCs in smoke from wood stoves or open fires.
Explains that when wood is ignited, volatile substances vaporize and burn, so combustion releases gaseous combustion products.
A student could extend this by checking standard lists of vapours released during pyrolysis/combustion of wood to see if benzene is produced during those volatile releases or incomplete combustion.
Notes burning traditional fuel for cooking/heating leads to indoor and outdoor air pollution (linking wood burning to air pollutant exposure).
Use this pattern (wood-burning → air pollution) plus external lists of common pollutants from biomass smoke to assess whether benzene commonly appears in such lists.
Says biomass burning emits gaseous organics such as formaldehyde and formic acid, showing that wood/forest fires produce specific volatile organic compounds.
A student could infer biomass burning emits VOCs and then consult chemical emission profiles from biomass burning to determine whether benzene is typically among those VOCs.
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- Identifies indoor products (paints and solvents) as contributors to indoor benzene concentrations.
- States that ventilation and source control (i.e., controlling indoor product sources) can reduce indoor benzene levels, implying indoor coatings/solvents are relevant sources.
- Demonstrates that indoor activities and materials (here, cigarette smoke) can be major indoor sources of benzene.
- Supports the general point that indoor sources can meaningfully contribute to indoor benzene exposure.
Lists volatile organic compounds (VOCs) indoor sources and explicitly names 'furniture polish' and 'wood preservatives' among products that emit VOCs (and separately notes formaldehyde).
A student could infer that finishes/varnishes or related wood-treatment products may likewise emit VOCs and then check if benzene is a VOC used or emitted by such products or measurable near varnished furniture.
States that indoor air can contain 'air toxins' and that exposure to multi-pollutant mixtures from indoor sources (e.g., diesel example) has health impact, indicating such mixtures may include species like VOCs.
One could extend this general rule to consider varnished furniture as a potential contributor to an indoor multi-pollutant mix and investigate whether benzene is among typical indoor 'air toxins' emitted by finishes.
Defines air pollution as addition of gases/vapours and links increased use of different fuels/processes to emission of toxic gases, establishing a general pattern that manufactured materials/processes emit gaseous pollutants.
Use the general definition to frame varnish off‑gassing as a source of gaseous contaminants and then look up whether varnish formulations or their solvents can include benzene.
Notes that some domestic activities (biomass burning) are major contributors to indoor pollution, illustrating that everyday household materials/processes commonly generate indoor pollutants.
By analogy, consider finishing/varnishing as an everyday household/materials process that could emit pollutants and seek specific data on benzene emissions from varnishes or coated wood.
Provides examples of named pollutants and their industrial/combustion sources, showing textbooks list specific pollutant↔source links as a pattern.
Apply this pattern: search for authoritative lists linking benzene to product types (e.g., solvents, varnishes) or for measurements of benzene near varnished furniture to evaluate the claim.
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States that HCFC blowing agents are used in rigid polyurethane foams and that foam production involves chemical agents that can be emitted.
A student could check whether polyurethane manufacturing or PU foams off‑gas volatile organic compounds (VOCs) and whether benzene is among typical VOCs from foam/blowing‑agent use or breakdown.
Notes that use of synthetic materials for building and furnishing increases indoor air pollution, linking man‑made materials (like PU products) to indoor emissions.
Use the general rule that synthetic furnishing materials can off‑gas VOCs to investigate whether polyurethane furniture emits benzene indoors (e.g., via product testing or VOC emission lists).
Gives a classification that lists plastics as primary pollutants — implying some synthetic/man‑made materials themselves can be direct pollutant sources.
Apply this pattern to polyurethane (a synthetic polymer) and research known primary pollutants emitted from plastics/polymers to see if benzene appears among common emissions.
Emphasises that air contains 'air toxins' and multi‑pollutant mixtures from various sources (including products/industry) that have health impacts.
Treat polyurethane products as potential contributors to indoor/outdoor 'air toxins' and look for empirical measurements of benzene in environments with PU use or manufacture.
Mentions that emissions from foam (and related products) release chemicals like chlorofluorocarbons, illustrating that foam products can be a source of chemical emissions.
Extend this example by examining emissions profiles of different foams (including PU foams) to see if benzene is listed among their emitted compounds.
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- [THE VERDICT]: Logical Sitter disguised as a Fact-Heavy Bouncer. While Shankar IAS/NCERTs don't explicitly list 'Benzene' for all 5, they list 'VOCs' for all 5. Benzene is the most famous VOC.
- [THE CONCEPTUAL TRIGGER]: Environmental Pollution > Indoor Air Quality > Volatile Organic Compounds (VOCs).
- [THE HORIZONTAL EXPANSION]: Memorize the 'Indoor Villains': 1) Formaldehyde (Plywood, glues, pressed wood). 2) Radon (Radioactive decay in basements). 3) Asbestos (Old insulation/roofing). 4) Carbon Monoxide (Faulty heaters). 5) BTEX (Benzene, Toluene, Ethylbenzene, Xylene) -> Traffic & Solvents.
- [THE STRATEGIC METACOGNITION]: Do not memorize infinite lists of chemicals. Learn the *properties*. Benzene is an aromatic hydrocarbon. Where do hydrocarbons come from? 1. Incomplete combustion (Exhaust, Smoke, Wood). 2. Evaporating solvents (Varnish, Paints, Glues/Polyurethane). If the source fits the property, mark it correct.
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Reference [8] states vehicle emissions contain VOCs; these emissions are central to the question of organic air pollutants from automobiles.
High‑yield for UPSC: understanding that vehicles emit VOCs helps connect transport to air‑pollution chemistry, policy (fuel standards, CNG/electric vehicles), and health impacts. It links to topics on urban air quality, emission control measures, and photochemical smog. Candidates should remember causes, control measures, and examples of VOC sources for practice and mains answers.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Y{r7 $ EilVIAONMEHT > p. 65
Reference [8] explains ground‑level ozone forms when vehicle NOx and VOCs interact in sunlight — directly tying vehicle exhaust to secondary pollutants.
Important for both prelims and mains: explains how primary vehicular emissions produce secondary pollutants (ozone, smog). Helps in answering questions on urban pollution episodes, health impacts, and mitigation strategies like fuel/vehicle norms and traffic management.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Y{r7 $ EilVIAONMEHT > p. 65
Reference [7] highlights that exhaust fumes can cause cancer; reference [9] shows petroleum hydrocarbons from automobiles enter the environment.
Vital for answer‑writing on environmental health: links vehicular pollution to public health concerns, supports policy discussions (phasing old vehicles, adopting cleaner fuels). Useful for case studies and questions on environmental governance and preventive measures.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Do you knaw? > p. 66
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Sources of Marine Pollution > p. 45
Several references state that tobacco smoke releases a wide range of harmful/toxic chemicals and contributes to indoor air pollution and passive smoking.
High-yield for UPSC environment and public health questions: helps classify indoor pollution sources, frame policy responses (smoking bans, awareness), and link to vulnerable groups (children, women). Useful across questions on air quality, health impacts, and mitigation strategies.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Pollutants > p. 66
- Science-Class VII . NCERT(Revised ed 2025) > Chapter 9: Life Processes in Animals > SCIENCE AND SOCIETY > p. 133
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Consequences of Air Pollution > p. 40
Evidence repeatedly identifies tobacco smoke as carcinogenic and causing lung irritation, chronic bronchitis, asthma and other respiratory illnesses.
Important for answering questions on non-communicable diseases, environmental health, and tobacco control policy. Helps connect pollutant sources to morbidity burden and public health interventions (campaigns, regulations).
- Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 6: Environmental Degradation and Management > Consequences of Air Pollution > p. 40
- Science-Class VII . NCERT(Revised ed 2025) > Chapter 9: Life Processes in Animals > SCIENCE AND SOCIETY > p. 133
- Science , class X (NCERT 2025 ed.) > Chapter 5: Life Processes > More to Know! > p. 89
References list volatile organic compounds and suspended particulate matter as indoor pollutants and enumerate indoor sources (household products, smoke, combustion).
Useful for framing questions on pollutant classification, indoor air quality assessment, and mitigation (ventilation, source control). Enables linking specific sources to pollutant types in analytical answers.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Pollutants > p. 66
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > Suspended particulate matter (SpM) > p. 64
- INDIA PEOPLE AND ECONOMY, TEXTBOOK IN GEOGRAPHY FOR CLASS XII (NCERT 2025 ed.) > Chapter 9: Geographical Perspective on Selected Issues and Problems > Air Pollution > p. 97
References identify biomass/domestic wood burning and agricultural/forest fires as major sources of brown carbon and smoke.
High-yield for environment and disaster management topics: links air pollution sources to climate forcing (brown/black carbon), health impacts, and wildfire management. Useful for questions on causes, effects, and mitigation of air pollution and for framing policy solutions.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 17: Climate Change > Possible Sources of Brown Carbon are > p. 258
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 5: Environmental Pollution > a) Rural > p. 65
- Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 14: Settlements > Environmental Degradation and Rural Settlements > p. 18
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Formaldehyde. It is the 'sibling' of Benzene in indoor pollution. Expect a question linking Formaldehyde to 'Pressed Wood Products' (particleboard, plywood), glues, and permanent-press fabrics.
The 'Pollutant Source' Heuristic: In Science/Environment, proving a source *never* emits a specific common pollutant is scientifically nearly impossible. Unless an option is absurd (e.g., 'Solar panels emit Benzene'), questions asking 'Which of these are sources/factors?' for a widespread pollutant usually result in 'All of the above' (Option D).
Link to GS-3 (Environment) & GS-2 (Health): 'Sick Building Syndrome'. As India urbanizes and seals buildings for AC efficiency, indoor accumulation of Benzene/Formaldehyde becomes a critical public health issue, necessitating Green Building Codes (GRIHA/LEED).
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