Environmental Health Practice Questions

Q: Which of the following chemicals is not included in the WHO's list of 10 chemicals of major public health concern?

Radium. The World Health Organization (WHO) has identified **10 chemicals or groups of chemicals** that constitute a major public health concern due to their widespread use, environmental persistence, and significant toxicity. **Explanation of the Correct Answer:** **D. Radium** is the correct answer because it is **not** included in the WHO’s top 10 list. While radium is a known radioactive hazard (linked to bone cancers and osteosarcoma), it is not considered a global "major public health concern" in the same category as the others, which have more pervasive environmental and industrial exposure routes affecting larger populations. **Explanation of Incorrect Options:** * **A. Arsenic:** Included. It is a major contaminant of groundwater in regions like West Bengal and Bangladesh, leading to chronic arsenicosis and skin/lung cancers. * **B. Asbestos:** Included. All forms of asbestos are carcinogenic, causing mesothelioma, lung cancer, and asbestosis. * **C. Dioxins:** Included. These are persistent organic pollutants (POPs) produced as by-products of industrial processes and waste incineration, known for their immunotoxic and reproductive effects. **High-Yield NEET-PG Facts:** To master this topic, memorize the complete **WHO List of 10 Chemicals of Major Public Health Concern**: 1. **Arsenic** 2. **Asbestos** 3. **Benzene** 4. **Cadmium** 5. **Dioxins and dioxin-like substances** 6. **Inadequate or excess Fluoride** 7. **Lead** (Most common cause of chronic metal poisoning) 8. **Mercury** (Associated with Minamata disease) 9. **Highly hazardous pesticides** 10. **Air pollution** (Specifically particulate matter and gases) **Clinical Pearl:** Note that **Lead** is often cited as the most important environmental toxin for children (neurotoxicity), while **Fluoride** is unique on this list because it is a concern in both deficiency (dental caries) and excess (fluorosis).

Q: In indoor air pollution, what produces carbon monoxide?

All of the above. **Explanation:** Carbon monoxide (CO) is a colorless, odorless, and non-irritating gas produced by the **incomplete combustion** of carbon-containing fuels. In indoor environments, any appliance that burns fuel (biomass, gas, kerosene, or coal) is a potential source of CO, especially if it is poorly ventilated or malfunctioning. * **Combustion equipment:** This is a broad category including internal combustion engines (generators) and furnaces. If operated in enclosed spaces, they rapidly accumulate lethal levels of CO. * **Stoves:** Both gas stoves and traditional biomass "chulhas" produce CO. Biomass fuel is a major contributor to indoor air pollution in rural India, leading to significant respiratory morbidity. * **Gas heaters:** Unvented or faulty gas space heaters are classic culprits for CO poisoning, particularly in poorly ventilated rooms during winter. Since all three categories involve the burning of fuel that can lead to incomplete combustion, **Option D (All of the above)** is the correct answer. **High-Yield Clinical Pearls for NEET-PG:** * **Mechanism of Toxicity:** CO has an affinity for hemoglobin that is **200–250 times greater** than that of oxygen, forming **Carboxyhemoglobin (COHb)**. This causes a leftward shift of the oxygen-dissociation curve, leading to tissue hypoxia. * **Clinical Presentation:** Often presents as "the great mimicker." Early symptoms include headache, dizziness, and nausea. A classic (but rare) sign is **cherry-red skin/mucosa**. * **Indicator of Indoor Air Pollution:** While CO is a major pollutant, **Particulate Matter (PM2.5)** is often considered the best indicator of health risks from biomass smoke. * **Treatment:** 100% High-flow oxygen (reduces COHb half-life from 5 hours to ~80 minutes). Hyperbaric oxygen is used in severe cases.

Q: High air velocity is measured by?

Anemometer. **Explanation:** The correct answer is **B. Anemometer**. In environmental health, monitoring air movement is crucial for assessing ventilation and thermal comfort. An **Anemometer** is the standard instrument specifically designed to measure **high air velocity** (wind speed). There are various types, such as the cup anemometer (common in meteorology) and the vane anemometer. **Analysis of Options:** * **Psychrometer (A):** This instrument consists of two thermometers (dry-bulb and wet-bulb) and is used to measure **humidity** (relative humidity), not air velocity. * **Kata Thermometer (C):** This is a high-yield distractor. While it also measures air velocity, it is specifically used for **low air velocities** (cooling power of air). It is particularly useful for assessing indoor ventilation and stagnant air. * **Hygrometer (D):** This is a general term for instruments used to measure the **moisture content** (humidity) in the atmosphere. **High-Yield Clinical Pearls for NEET-PG:** * **Kata Thermometer:** If the question specifies "low air velocity" or "cooling power of air," Kata Thermometer is the answer. A "Silvered" Kata thermometer is used to eliminate radiation errors. * **Globe Thermometer:** Used to measure **mean radiant temperature** (heat radiation). * **Corrected Effective Temperature (CET):** This index is calculated using the Globe thermometer, Anemometer, and Psychrometer to assess the combined effect of air temperature, humidity, and radiant heat on the human body. * **Comfort Zone:** In India, the ideal indoor temperature for comfort is generally considered to be **25°C to 27°C**.

Q: All of the following are water-borne diseases except?

Scabies. **Explanation:** The classification of water-related diseases is a high-yield topic for NEET-PG. To answer this correctly, one must distinguish between **water-borne** and **water-washed** diseases. **1. Why Scabies is the correct answer:** Scabies is classified as a **water-washed disease**, not a water-borne disease. Water-washed diseases occur due to a lack of adequate water for personal hygiene and washing. When water is scarce, skin and eye infections spread easily through direct contact. Other examples include trachoma and pediculosis. **2. Why the other options are incorrect:** * **Salmonella (Typhoid/Paratyphoid):** These are classic **water-borne diseases**. They are transmitted via the feco-oral route when pathogenic microorganisms are ingested through contaminated drinking water. * **Cholera:** Caused by *Vibrio cholerae*, this is the prototype of water-borne diseases, often leading to explosive outbreaks when a common water source is contaminated. * **Hepatitis A:** This is a viral infection transmitted through the feco-oral route, primarily via contaminated water or food. **Clinical Pearls for NEET-PG:** * **Water-borne:** Ingesting contaminated water (e.g., Cholera, Typhoid, Amoebiasis, Giardiasis, Hepatitis A & E). * **Water-washed:** Lack of water for hygiene (e.g., Scabies, Trachoma, Conjunctivitis). * **Water-based:** Aquatic intermediate host involved (e.g., Schistosomiasis, Guinea worm). * **Water-related (Insect Vector):** Insects breeding in/near water (e.g., Malaria, Filariasis, Dengue). * **Note:** Hepatitis E is the most common cause of epidemic viral hepatitis in India, transmitted via the water-borne route.

Q: All are components of sewer gas except?

SO2. **Explanation:** The composition of **sewer gas** is a high-yield topic in Environmental Health, specifically concerning the anaerobic decomposition of organic matter in sewage systems. **Why SO2 is the correct answer:** Sewer gas is primarily a mixture of gases produced by the action of anaerobic bacteria on waste. **Sulfur Dioxide (SO2)** is typically a byproduct of industrial combustion (like burning fossil fuels) and is not a natural product of organic decomposition in sewers. Therefore, it is not a component of sewer gas. **Analysis of other options:** * **Methane (CH4):** This is a major component of sewer gas. It is highly flammable, odorless, and can lead to explosive hazards in confined spaces. * **Hydrogen Sulfide (H2S):** This is the most characteristic and dangerous component. It gives sewer gas its "rotten egg" odor. It is highly toxic and can cause "olfactory fatigue," where a person loses the ability to smell the gas before reaching lethal concentrations. * **Carbon Dioxide (CO2):** A common byproduct of the microbial breakdown of organic compounds, CO2 displaces oxygen in sewers, contributing to the risk of asphyxiation for sanitation workers. **NEET-PG High-Yield Pearls:** 1. **Primary Hazard:** The most immediate life-threatening gas in sewers is **Hydrogen Sulfide (H2S)**, which acts as a chemical asphyxiant similar to cyanide. 2. **Composition:** Sewer gas consists of Methane (approx. 25%), CO2 (approx. 5%), Nitrogen, and trace amounts of H2S and Ammonia. 3. **Occupational Health:** Workers entering manholes must follow the "Rule of Ventilation" and use gas detectors to check for oxygen deficiency and toxic gas buildup. 4. **Clinical Sign:** H2S poisoning can be identified by the smell of rotten eggs on the breath or clothing of the victim (though this disappears at high concentrations).

Q: Which of the following is NOT a waterborne disease?

Fish tapeworm. ### Explanation The classification of water-related diseases is a high-yield topic in Community Medicine. To answer this correctly, one must distinguish between **water-borne** diseases and **water-based** diseases. **1. Why Fish Tapeworm is the Correct Answer:** Fish tapeworm (*Diphyllobothrium latum*) is classified as a **water-based disease**, not water-borne. In water-based diseases, the pathogen spends part of its life cycle in an intermediate aquatic host (like crustaceans or fish). Humans are infected by **ingesting undercooked fish**, not by drinking contaminated water directly. **2. Analysis of Incorrect Options:** * **Typhoid (Option A):** Caused by *Salmonella typhi*, it is a classic **water-borne** disease transmitted via the feco-oral route through contaminated drinking water. * **Hepatitis A (Option C):** This viral infection is primarily transmitted through the feco-oral route via contaminated water or food, making it a major **water-borne** viral pathogen. * **Cholera (Option D):** Caused by *Vibrio cholerae*, it is the prototype of **water-borne** diseases, often leading to explosive outbreaks when a common water source is contaminated. **3. NEET-PG High-Yield Pearls:** * **Water-borne:** Caused by ingestion of water contaminated by human/animal feces (e.g., Cholera, Typhoid, Amoebiasis, Hepatitis A/E). * **Water-washed:** Due to poor personal hygiene/lack of water (e.g., Scabies, Trachoma). * **Water-based:** Pathogen spends part of its life cycle in aquatic intermediate hosts (e.g., Schistosomiasis, Guinea worm, Fish tapeworm). * **Water-related insect vector:** Diseases spread by insects breeding near water (e.g., Malaria, Filariasis). * **Hepatitis E** is the most common cause of epidemic viral hepatitis in India, transmitted via the water-borne route.

Q: Which gas contributes to global warming but is not considered a greenhouse gas?

Sulfur dioxide (SO2). ### Explanation The core of this question lies in distinguishing between **Greenhouse Gases (GHGs)**, which trap infrared radiation to warm the atmosphere, and other pollutants that influence global temperatures through different mechanisms. **Why Sulfur Dioxide (SO2) is the correct answer:** Sulfur dioxide is **not** a greenhouse gas. In fact, it is primarily known for its **cooling effect** (negative radiative forcing) because it forms sulfate aerosols that reflect sunlight away from the Earth. However, it is considered a "contributor" to global warming in a broader environmental context because it is a precursor to acid rain and influences atmospheric chemistry. In many competitive exams, it is classified as a non-GHG pollutant often found in lists alongside actual GHGs to test this specific distinction. **Analysis of Incorrect Options:** * **Carbon dioxide (CO2):** The most abundant anthropogenic GHG; it is the primary driver of the enhanced greenhouse effect. * **Chlorofluorocarbons (CFCs):** These are potent GHGs with a high global warming potential (GWP) and are also responsible for ozone layer depletion. * **Ozone (O3):** While beneficial in the stratosphere (UV protection), ground-level (tropospheric) ozone is a significant greenhouse gas and a major component of photochemical smog. **High-Yield NEET-PG Pearls:** * **Major GHGs:** CO2, Methane (CH4), Nitrous Oxide (N2O), CFCs, and Water Vapor. * **Kyoto Protocol:** Focuses on reducing GHG emissions to combat climate change. * **SO2 Clinical Link:** It is a potent respiratory irritant causing bronchoconstriction; it is a major trigger for **exacerbations of Asthma and COPD**. * **Acid Rain:** Primarily caused by SO2 and Nitrogen oxides (NOx).

Question 1

Which of the following chemicals is not included in the WHO's list of 10 chemicals of major public health concern?

Accepted Answer

Radium

Answer

Arsenic

Answer

Asbestos

Answer

Dioxin

Question 2

In indoor air pollution, what produces carbon monoxide?

Accepted Answer

All of the above

Answer

Combustion equipment

Answer

Stoves

Answer

Gas heaters

Question 3

What are the proposed guideline values for Radioactivity in drinking water?

Accepted Answer

Gross alpha activity 0.1 Bq/L and Gross beta activity 1.0 Bq/L

Answer

Gross alpha activity 1.0 Bq/L and Gross beta activity 10.0 Bq/L

Answer

Gross alpha activity 1.0 Bq/L and Gross beta activity 0.1 Bq/L

Answer

Gross alpha activity 10 Bq/L and Gross beta activity 1.0 Bq/L

Question 4

High air velocity is measured by?

Accepted Answer

Anemometer

Answer

Psychrometer

Answer

Kata thermometer

Answer

Hygrometer

Question 5

All of the following are water-borne diseases except?

Accepted Answer

Scabies

Answer

Salmonella

Answer

Cholera

Answer

Hepatitis - A

Question 6

All are components of sewer gas except?

Accepted Answer

SO2

Answer

H2S

Answer

CO2

Answer

Methane

Question 7

What is the advantage of a single chamber incinerator?

Accepted Answer

Good disinfection efficiency

Answer

Effective for thermally resistant articles

Answer

Useful for cytotoxic drugs

Answer

Low pollutant emissions

Question 8

Which of the following is NOT a waterborne disease?

Accepted Answer

Fish tapeworm

Answer

Typhoid

Answer

Hepatitis A virus

Answer

Cholera

Question 9

Which of the following statements regarding fluorosis is incorrect?

Accepted Answer

Fluorosis is the most common cause of dental caries in children.

Answer

Fluorosis can cause fluoride deposition in bones.

Answer

Defluoridation can be achieved by the Nalgonda technique.

Answer

Fluorosis can cause genu valgum.

Question 10

Which gas contributes to global warming but is not considered a greenhouse gas?

Accepted Answer

Sulfur dioxide (SO2)

Answer

Carbon dioxide (CO2)

Answer

Chlorofluorocarbon (CFC)

Answer

Ozone (O3)

Environmental Health — MCQs

Environmental Health — MCQs

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