Environment and Health

🟢 Lite — Quick Review (1h–1d)

Rapid summary for last-minute revision before your NEET PG exam.

Environment and Health — Key Facts

Water-Related Diseases (Bradley’s Classification) — Very Important

Category	Mechanism	Examples
Waterborne	Pathogen ingested	Cholera, Typhoid, Hepatitis A, Dysentery
Water-washed	Insufficient hygiene	Trachoma, Scabies, Skin infections
Water-based	Parasite uses water host	Schistosomiasis, Dracunculiasis
Water-related vector	Vector breeds in water	Malaria, Dengue, Filariasis

Air Pollution

• PM2.5: Most harmful, reaches alveoli
• WHO limit: PM2.5 < 5 μg/m³ annual average
• AQI categories: Good to Severe (6 categories in India)

BMW Color Coding — Important

• Yellow: Human anatomical waste → Incineration
• Red: Sharps, plastic → Autoclave/Microwave
• White/Blue: Glass, metallic → Autoclave then puncture

⚡ NEET PG High-Yield: Bradley classification of water-related diseases is very commonly asked.

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🟡 Standard — Regular Study (2d–2mo)

Chapter: Environment and Health

1.1 Water and Health

Water Requirements

• Minimum: 20 liters/person/day
• Moderate: 50-100 L/p/d
• Optimal: 150-200 L/p/d

Waterborne Diseases (Bradley Classification)

Waterborne (Pathogen ingested):

• Cholera (Vibrio cholerae): Rice-water stools, severe dehydration
  • Treatment: ORS + Antibiotics (Azithromycin)
  • Prevention: Oral cholera vaccine
• Typhoid (Salmonella typhi): Enteric fever, continuous fever
  • Diagnosis: Blood culture (gold standard)
  • Prevention: Vi polysaccharide vaccine (Typbar)
• Hepatitis A: Self-limiting, fecal-oral, jaundice
• Bacillary Dysentery (Shigella): Bloody diarrhea, tenesmus

Water-washed (Insufficient water for hygiene):

• Trachoma (Chlamydia trachomatis): Prevents eye infection with hygiene
• Scabies, skin infections

Water-based (Parasite uses water intermediate host):

• Schistosomiasis (Bilharzia): Snail as intermediate host
• Dracunculiasis (Guinea worm): Cyclops water flea

Water-related vector (Vector breeds in water):

• Malaria (Anopheles mosquito)
• Dengue (Aedes aegypti)
• Filariasis (Culex)

1.2 Water Quality

Indian Standards (BIS 10500:2012)

• pH: 6.5-8.5
• Fluoride: 1.0 mg/L (deficiency → caries; excess → fluorosis)
• Nitrate: 45 mg/L (max)
• Lead: 0.01 mg/L

Water Purification

1. Coagulation/Flocculation: Alum + lime
2. Sedimentation: Flocs settle
3. Filtration: Rapid sand filter
4. Disinfection: Chlorination

Chlorination

• Breakpoint chlorination: Add chlorine until free residual persists
• Free residual chlorine: 0.2-0.5 mg/L after 30 min

Coliform Testing

• Total coliform: All coliform bacteria
• Fecal coliform (E. coli): Indicates fecal contamination
• Standard: 0 coliform/100 mL for drinking

1.3 Air Pollution

Criteria Pollutants

1. PM2.5 (≤2.5μm): Most harmful, alveolar deposition
2. PM10 (≤10μm): Upper airway
3. SO₂: Respiratory irritant, bronchoconstriction
4. NO₂: Respiratory irritant
5. CO: Carboxyhemoglobin, reduces O₂ carrying capacity
6. O₃: Lung damage
7. Pb: Neurological damage

Health Effects

• Acute: Eye irritation, cough, asthma exacerbation
• Chronic: COPD, lung cancer, cardiovascular disease, stroke

Air Quality Index (AQI) — India

AQI	Category	Impact
0-50	Good	Minimal
51-100	Satisfactory	Minor breathing discomfort
101-200	Moderate	Breathing discomfort to sensitive
201-300	Poor	Breathing discomfort on prolonged exposure
301-400	Very Poor	Respiratory illness
401-500	Severe	Serious health effects

1.4 Indoor Air Pollution

Source: Biomass fuel combustion (wood, crop residue, cow dung) Primary victims: Women and children

Emissions: PM2.5, CO, PAHs, formaldehyde

Health Effects:

• ARI (pneumonia in children)
• COPD, lung cancer, cataracts
• 2.3 million deaths/year globally

Solution: Improved cookstoves (Prakashphal), LPG (PMUY - Pradhan Mantri Ujjwala Yojana)

1.5 Solid Waste Management

Municipal Solid Waste Composition

• Biodegradable: 40-50% (food, garden waste)
• Recyclable: 20-30% (paper, plastic, glass)
• Inert: 30-40% (debris, ash)

Treatment Methods

• Composting: Aerobic/anaerobic
• Incineration: Energy recovery
• Landfill: Sanitary (engineered)

Biomedical Waste (BMW Rules 2016)

Color	Waste Type	Treatment
Yellow	Anatomical, soiled dressings	Incineration
Red	Sharps, plastic	Autoclave/Microwave/Chemical
White/Blue	Glassware, metallic	Autoclave → Puncture/Combine

1.6 Sewage Treatment

Primary Treatment: Physical (screening, sedimentation) Secondary Treatment: Biological (activated sludge) Tertiary Treatment: Chemical (nutrient removal)

1.7 Radiation and Health

• Non-ionizing: Radio waves, UV (less harmful)
• Ionizing: X-rays, gamma rays (harmful)

Effects: Acute radiation syndrome, cancer, cataracts

Protection (Time, Distance, Shielding):

• Minimize exposure time
• Maximize distance (inverse square law)
• Use shielding (lead, concrete)

1.8 Climate Change

Health Impacts:

• Heat-related mortality (heat waves)
• Vector-borne disease range expansion
• Water-borne diseases after floods
• Food insecurity, malnutrition
• Mental health impacts

1.9 Occupational Health

Hazards

• Physical: Heat, noise, radiation, dust
• Chemical: Lead, mercury, benzene, asbestos
• Biological: Bacteria, viruses
• Ergonomic: Repetitive strain

Prevention (Hierarchy of Controls)

1. Elimination
2. Substitution
3. Engineering (ventilation)
4. Administrative
5. PPE (last resort)

Factory Act 1948

• Working hours: ≤48 hrs/week
• IMR: ~28/1000 (India 2023)
• ESI Act 1948: Health insurance for factory workers

1.10 NEET PG High-Yield Points

⚡ Commonly Asked:

1. Bradley classification (4 categories) — Very important
2. Cholera: Rice-water stools, ORS
3. Typhoid: Blood culture gold standard
4. Hepatitis A: Self-limiting, fecal-oral
5. Fluoride: Deficiency → caries; Excess → fluorosis
6. PM2.5: Most harmful pollutant
7. AQI: 6 categories in India
8. Indoor air pollution: Biomass → women/children
9. BMW color coding: Yellow (incineration), Red (autoclave)
10. Sewage treatment: Primary (physical), Secondary (biological)
11. Factory Act 1948: ≤48 hrs/week
12. Occupational hierarchy: Elimination → PPE