Environmental Health (Water, Air, Sanitation, Radiation, Housing) MCQs

Community Medicine (PSM) · 122 free questions with answers & explanations.

1. As per BIS (Bureau of Indian Standards) and WHO guidelines for drinking water quality, the permissible limit of total coliform in treated piped water supply is:
2. The National Ambient Air Quality Standard (NAAQS) for PM2.5 in India (24-hour mean) is:
3. As per BIS 10500:2012, the PERMISSIBLE limit (in the absence of an alternate water source) for fluoride in drinking water in India is:
4. Sick Building Syndrome (SBS) is most commonly caused by inadequate ventilation combined with accumulation of which indoor pollutants?
5. The WHO permissible limit for fluoride in drinking water is 1.5 mg/L. At concentrations between 3–5 mg/L, which clinical manifestation is most characteristic?
6. A factory chimney releases sulphur dioxide and particulate matter. During a temperature inversion episode, photochemical smog forms when SO₂ reacts with sunlight and atmospheric oxygen. The primary secondary pollutant responsible for the characteristic oxidant smog is:
7. The Biochemical Oxygen Demand (BOD) of a water sample at 20°C after 5 days is 3 mg/L. The National Standards for water quality classify this level as:
8. The Air Quality Index (AQI) in India uses which pollutant as the primary indicator for categorizing air as 'Hazardous' (AQI 401–500)?
9. The National Ambient Air Quality Standard (NAAQS) in India for PM2.5 (24-hour average) is:
10. According to WHO guidelines 2017, the minimum free residual chlorine (FRC) required at the consumer's end in a piped water supply for safe drinking water is:
11. The permissible limit of fluoride in drinking water as per IS:10500 (BIS standards) is 1.0 mg/L. At what level does fluoride cause skeletal fluorosis with radiological changes?
12. The Harza coefficient is used in environmental health to assess:
13. The WHO Air Quality Guidelines (2021) set the annual mean PM2.5 standard at:
14. Trihalomethanes (THMs) in drinking water are formed as a result of:
15. The BIS (Bureau of Indian Standards) standard for drinking water quality specifies the maximum permissible limit of nitrates in drinking water as:
16. The Air Quality Index (AQI) in India is based on ambient concentration of which SIX pollutants as primary indicators?
17. The Swachh Bharat Mission (Grameen) Phase 2 (2020–2025) focuses on which key aspect of sanitation beyond what Phase 1 achieved?
18. According to WHO and BIS standards for drinking water quality, what is the permissible limit of fluoride in drinking water in India, and what is the maximum permissible limit in the absence of an alternative source?
19. The WHO air quality guideline (2021) for PM2.5 was revised downward compared to 2005. The revised 24-hour mean guideline value is:
20. Which chlorination byproduct is the primary concern in drinking water chlorinated with organic matter present, and what is its significance?
21. During chlorination of drinking water, the 'break-point chlorination' refers to the point at which:
22. The Noise Pollution (Regulation and Control) Rules 2000 in India specify daytime (6 AM to 10 PM) ambient noise limit for industrial areas as:
23. Photochemical smog (Los Angeles type smog) is chemically distinct from classical London smog. Which pollutant is the PRINCIPAL secondary pollutant in photochemical smog that causes its characteristic eye and respiratory irritation?
24. Fluorosis in India is related to high fluoride in drinking water. The WHO and BIS permissible limit for fluoride in drinking water is 1.0–1.5 mg/L. Excess fluoride in water PRIMARILY damages which of the following tissues in adults?
25. The 'ALARA' principle in radiation protection stands for 'As Low As Reasonably Achievable.' In practice, which combination of measures best operationalizes ALARA for a diagnostic radiology worker?
26. A village in Rajasthan has groundwater fluoride of 5.2 mg/L. Children aged 8–12 years show mottled enamel and adults show lumbar kyphosis with reduced spinal mobility. The radiological finding expected in advanced skeletal fluorosis is:
27. The permissible fluoride level in drinking water as per Bureau of Indian Standards (BIS: 10500) is:
28. The E. coli standard for piped water supply treated and distributed (not at source) as per Indian standards is:
29. The concept of 'sick building syndrome' is distinct from 'building-related illness'. The defining characteristic of sick building syndrome is that:
30. Under the concept of minimum requirements for healthy housing (Winslow criteria), which is considered the MOST important environmental determinant?
31. The Jal Jeevan Mission (JJM) aims to provide functional household tap connections (FHTC) to all rural households by 2024. Under JJM, what is the drinking water service level standard (per capita per day supply) considered adequate for rural households?
32. The National Ambient Air Quality Standards (NAAQS) in India for PM2.5 are set at what 24-hour average concentration (µg/m³)?
33. In the context of radiation safety, the effective dose to a radiation worker from occupational exposure is limited to 20 mSv per year averaged over 5 years, with no single year exceeding 50 mSv. Which unit correctly represents the SI unit for radiation absorbed dose AND the unit for effective dose (accounting for tissue weighting factors)?
34. A community residing in a flood-prone district uses contaminated groundwater containing high levels of fluoride (7 ppm). The permissible limit of fluoride in drinking water as per BIS/Indian standards is 1.0 mg/L (1 ppm), and the maximum permissible in absence of alternative is 1.5 mg/L. Long-term consumption above 3–6 ppm causes skeletal fluorosis. Which other element in Indian groundwater, especially in Indo-Gangetic plains, co-occurs geochemically with fluoride and also causes chronic toxicity?
35. The World Health Organisation's revised guideline value for arsenic in drinking water is 10 μg/L. Chronic arsenicosis from groundwater contamination in West Bengal produces which dermatological manifestation considered pathognomonic for advanced exposure?
36. In air quality assessment, PM2.5 is considered more hazardous than PM10 primarily because:
37. Fluorosis in endemic areas of Rajasthan is caused by ingestion of groundwater containing fluoride exceeding __ mg/L, and the earliest clinical manifestation is:
38. The Minamata disease epidemic in Japan (1956) exemplified a specific environmental health principle concerning biomagnification. The causative agent and the principle best illustrated are:
39. In the context of ionising radiation protection, the concept of 'ALARA' specifically implies that radiation exposure should be:
40. A district faces an outbreak of methemoglobinaemia ('blue-baby syndrome') in infants receiving formula made with well water. The most likely contaminant responsible is:
41. The National Ambient Air Quality Standards (NAAQS) in India set the 24-hour average standard for PM2.5 (fine particulate matter) at:
42. A community's water supply has a residual chlorine level of 0.2 mg/L at the point of consumption after municipal treatment. Which conclusion is MOST correct?
43. A uranium mine worker undergoes periodic health surveillance for radon exposure. The unit used to quantify radiation dose received by body tissues in occupational health monitoring is:
44. A municipal corporation measures a Biochemical Oxygen Demand (BOD) of 250 mg/L in a river receiving industrial effluent. This value indicates:
45. BIS standard IS 10500:2012 permits a maximum permissible limit of arsenic in drinking water of 0.01 mg/L. In districts of West Bengal with groundwater arsenic above 0.05 mg/L, long-term exposure most characteristically causes:
46. The WHO Air Quality Guidelines (AQG) 2021 reduced the annual mean PM2.5 standard to 5 µg/m³. The primary reason PM2.5 is more hazardous than PM10 is:
47. A community well used by 500 families tests positive for coliform organisms. Shock chlorination is performed. The concentration of free residual chlorine that must be maintained at the consumer's tap after distribution to ensure microbiological safety is:
48. In the context of non-ionising radiation, extremely low frequency (ELF) electromagnetic fields (from power lines) have been classified by IARC as Group 2B (possibly carcinogenic). The specific malignancy with strongest epidemiological evidence is:
49. The WHO Air Quality Guidelines (AQG) 2021 set a 24-hour mean concentration limit for PM2.5 at:
50. A community health officer inspects a village well. The 'sanitary survey score' approach to water quality assurance evaluates risk based on:
51. Regarding radiation safety, the annual occupational dose limit for radiation workers (effective dose) as per AERB regulations in India is:
52. The Bureau of Indian Standards (BIS IS 10500:2012) specifies a permissible limit for fluoride in drinking water of 1.0 mg/L (desirable) and 1.5 mg/L (permissible in absence of alternative). Chronic exposure above 1.5 mg/L primarily causes:
53. The WHO Air Quality Guidelines (2021 update) revised the annual PM2.5 guideline value downward from 10 µg/m³ to:
54. A cluster of cases of infant methemoglobinemia ('blue baby syndrome') is reported in a village. Investigations reveal contamination of shallow wells with agricultural runoff. The most likely contaminant causing this condition is:
55. Radon (Rn-222), a naturally occurring radioactive gas, is the second leading cause of lung cancer after tobacco smoking. Its primary source in indoor environments is:
56. The National Ambient Air Quality Standards (NAAQS) in India set the 24-hour average PM2.5 standard at:
57. Minamata disease was caused by contamination of the food chain (fish and shellfish) with:
58. The Chernobyl accident (1986) increased population exposure to which radioiodine isotope, resulting in a surge of which cancer in the subsequent decade?
59. The Vernier scale (Wentworth grading) is used to classify drinking water quality based on turbidity measured in Nephelometric Turbidity Units (NTU). The maximum permissible turbidity for treated piped water supply in India according to BIS IS:10500 is:
60. The 'most probable number' (MPN) method is used in water quality assessment to detect:
61. The National Ambient Air Quality Standards (NAAQS) in India set the 24-hour mean PM2.5 standard at:
62. The 'Oldt' formula is used to estimate the number of latrines required in a camp situation. Which parameter does it incorporate?
63. Trihalomethanes (THMs) in drinking water are formed when:
64. The 'effective dose' in radiation protection is measured in sieverts (Sv) and accounts for:
65. The 'over-crowding' in housing is measured by the standard of cubic feet of air space per person. The minimum recommended air space per adult in a sleeping room is:
66. Under BIS standard IS:10500:2012 (revised), the permissible limit of arsenic in drinking water in India is:
67. The ambient air quality standard for PM2.5 (24-hour average) as per National Ambient Air Quality Standards (NAAQS 2009, CPCB India) is:
68. In water purification, slow sand filtration removes pathogens primarily through which mechanism?
69. The WHO permissible limit for arsenic in drinking water is 0.01 mg/L. Chronic arsenic toxicity from groundwater in Bangladesh and West Bengal most characteristically causes:
70. The 'Biological Oxygen Demand' (BOD) of water is used to assess:
71. Under the Jal Jeevan Mission (JJM), the target is to provide tap water connections to every rural household. The minimum service level standard for individual household connections under JJM is:
72. PM2.5 (particulate matter ≤ 2.5 µm diameter) is considered more harmful than PM10 primarily because:
73. The IS:10500 (BIS, 2012) standard for drinking water in India specifies the permissible limit of fluoride in the absence of an alternative source as:
74. A city monitors ambient air quality under India's National Ambient Air Quality Standards (NAAQS, 2009). The 24-hour average standard for PM2.5 is:
75. Minamata disease is caused by chronic exposure to which environmental pollutant through consumption of contaminated fish?
76. The 'Overcrowding Standard' for housing as per the National Building Code recommends a minimum floor space of how many square metres per person for healthy living?
77. The WHO and BIS standard for residual free chlorine in treated piped water supply at consumer's tap is:
78. Arsenicosis (chronic arsenic poisoning from groundwater) in India is most prevalent in which states?
79. PM2.5 particles in ambient air are more harmful than PM10 because they:
80. The Swachh Bharat Mission (SBM) declared India 'Open Defecation Free' (ODF) in 2019 based on toilet coverage reaching nearly 100%. Which indicator BEST measures sanitation impact beyond toilet construction?
81. The WHO guideline value for arsenic in drinking water is 10 μg/L. Chronic exposure to arsenic in drinking water at levels above this threshold is MOST strongly associated with:
82. PM2.5 refers to particulate matter with aerodynamic diameter of 2.5 μm or less. The primary reason PM2.5 is more hazardous than PM10 is that PM2.5:
83. The Jal Jeevan Mission (JJM) launched in 2019 aims to provide Functional Household Tap Connections (FHTC) to all rural households by 2024. A 'functional' tap connection under JJM is defined as providing water at what minimum standard?
84. According to WHO standards, the permissible limit of fluoride in drinking water is:
85. The measure of air pollution that has the greatest impact on human respiratory health due to its ability to penetrate deep into alveoli is:
86. The Swachh Bharat Mission (Gramin) Phase 2 targets achieving which status across all villages in India?
87. The Bureau of Indian Standards (BIS) acceptable limit for nitrate in drinking water (IS:10500) and the WHO guideline value are respectively:
88. The Minamata disease outbreak in Japan was caused by environmental pollution with which heavy metal, leading to which type of pathology?
89. Biochemical Oxygen Demand (BOD) of a water sample measures:
90. The WHO Global Air Quality Guidelines (2021) revised the annual mean PM2.5 standard to:
91. Fluorosis from excess fluoride in drinking water presents with dental fluorosis at fluoride levels above which threshold?
92. The HEPA (High-Efficiency Particulate Air) filter used in hospital isolation rooms is designed to remove particles of what size with ≥99.97% efficiency?
93. The WHO guideline value for arsenic in drinking water is 10 μg/L. Chronic arsenic poisoning from drinking water primarily causes which skin manifestation?
94. The 'health of housing' indicator that measures the number of persons per room in a dwelling is called:
95. The maximum permissible limit (MPL) for fluoride in drinking water as per BIS (Bureau of Indian Standards) IS 10500:2012 is:
96. The WHO guideline value for fluoride in drinking water is 1.5 mg/L. In India, endemic fluorosis is characterized by dental fluorosis at fluoride levels above:
97. Minamata disease is caused by contamination of water and marine food with:
98. The National Ambient Air Quality Standards (NAAQS) in India set a 24-hour average PM2.5 standard of:
99. As per BIS (Bureau of Indian Standards) IS 10500:2012, the permissible limit for arsenic in drinking water in India is:
100. Which indicator organism is used to assess faecal contamination of drinking water in India's water quality surveillance under NITI Aayog and BIS standards?
101. In photochemical smog, the primary pollutant responsible for the secondary formation of peroxyacetyl nitrate (PAN) and ozone in the atmosphere is:
102. The 'Swachh Bharat Mission (Gramin)' Phase 2 (2020–2025) focuses on which sustainability goal beyond the Phase 1 achievement of Open Defecation Free (ODF) status?
103. The Biochemical Oxygen Demand (BOD) of water is a measure of:
104. The WHO guideline value for arsenic in drinking water is:
105. The Jal Jeevan Mission (JJM) aims to provide safe and adequate drinking water through individual household tap connections by the year:
106. Latent heat of vaporization of water (used in Kata thermometer calculation to measure effective temperature) is used to assess which environmental parameter?
107. The permissible limit of fluoride in drinking water as per BIS (IS:10500:2012) is:
108. Sick Building Syndrome (SBS) is MOST characteristically caused by:
109. Biochemical Oxygen Demand (BOD) is BEST used to assess:
110. The Air Quality Index (AQI) threshold above which outdoor physical activity should be avoided for sensitive groups (children, elderly, those with respiratory disease) is:
111. The WHO guideline value for arsenic in drinking water is 10 μg/L. The permissible limit set by BIS (Bureau of Indian Standards) for drinking water is:
112. The CPCB (Central Pollution Control Board) National Ambient Air Quality Standard for PM2.5 in India is:
113. Slow sand filtration (biological filtration) differs from rapid sand filtration primarily because:
114. The WHO guideline value for arsenic in drinking water is 10 µg/L; however, India's IS 10500 standard permits up to 50 µg/L as the permissible limit. Chronic arsenic exposure at levels >50 µg/L MOST characteristically causes which triad?
115. Under the Swachh Bharat Mission (Grameen) Phase II, what is the PRIMARY focus area distinguishing it from Phase I?
116. The Ringelmann chart is used to assess which type of environmental pollution?
117. The BIS (Indian Standard) acceptable limit for fluoride in drinking water is 1.0 mg/L, and the permissible limit (in absence of alternative) is 1.5 mg/L. Fluoride concentration above 1.5 mg/L for prolonged periods causes which condition?
118. The National Ambient Air Quality Standards (NAAQS) in India for PM2.5 (24-hour average) is:
119. Chlorination of water kills most bacteria and viruses but is INEFFECTIVE against which pathogen at standard doses used in community water treatment?
120. The Swachh Bharat Mission (Gramin) Phase II focuses primarily on achieving which sanitation goal?
121. Sick Building Syndrome (SBS) is primarily associated with which indoor air pollutant or condition?
122. Threshold Limit Value-Ceiling (TLV-C) in occupational exposure is defined as: