Environmental and Occupational Health

Water

• Requirement: WHO minimum 15–20 L/person/day; JJM rural 55 lpcd (FHTC); urban 135 lpcd (sewered).
• Sanitary well: ≥ 15 m from latrines, lined ≥ 6 m, parapet ≥ 70–75 cm, platform, cover, hand pump.
• Large‑scale: storage → coagulation (alum) → sedimentation → filtration → chlorination. Slow sand: schmutzdecke, scraping, 99.9% bacteria. Rapid sand: alum, backwashing, 40–50× faster.
• Chlorine: HOCl (70–80× OCl⁻), best at pH ≈ 7; breakpoint; free residual 0.5 mg/L after 1 h; consumer end ≥ 0.2 mg/L. Doesn't reliably kill spores, Cryptosporidium, hepatitis A/E at usual doses. OT/OTA/DPD tests. Double‑pot method; Horrocks' apparatus.
• BIS IS 10500:2012: turbidity 1 (5) NTU; pH 6.5–8.5; TDS 500 (2,000); fluoride 1.0 (1.5); nitrate 45; arsenic 0.01 mg/L; **E. coli not detectable in 100 mL**.

Air, housing, noise, radiation, heat

• WHO AQG 2021: PM₂.₅ 5 annual / 15 24‑h; PM₁₀ 15/45. NAAQS: PM₂.₅ 40/60; PM₁₀ 60/100. AQI 0–500 in 6 bands. NCAP 2019 (131 cities); Ujjwala 2016; BS‑VI 2020.
• Ventilation: 3,000 ft³/person/hour; AIIR ≥ 12 ACH. CET comfort 25–27 °C. WBGT for work.
• Overcrowding: 1 room 2, 2 rooms 3, 3 rooms 5, 4 rooms 7, 5+ rooms 10 (+2 each); infants not counted, 1–10 years = ½.
• Noise: occupational 90 dB(A) × 8 h (action 85); NIHL notch at 4 kHz; silence zone 50/40 dB within 100 m of hospitals.
• Radiation: ICRP/AERB 20 mSv/year (workers, 5‑year average), 1 mSv/year (public); justification, ALARA, limits; time, distance, shielding; TLD badges.
• Heatstroke: > 40 °C + CNS dysfunction → cool first. IMD heat wave: ≥ 40 °C plains with departure ≥ 4.5 °C, or ≥ 45 °C. NPCCHH 2019; Ahmedabad HAP 2013.

Sanitation and waste

• F‑diagram: sanitation = primary barrier. JMP ladder → safely managed.
• Twin‑pit pour‑flush (rural India); septic tank (24 h retention); trench latrines in camps.
• Sewage: preliminary → primary sedimentation → secondary (activated sludge, trickling filter, oxidation pond) → tertiary. BOD₅ (5 days, 20 °C).
• SBM 2014; ODF (rural) 2019; ODF Plus; manual scavenging banned (2013); NAMASTE.
• SWM Rules 2016: wet, dry, domestic hazardous. Composting: Indore (aerobic), Bangalore (anaerobic).
• BMW Rules 2016: yellow (anatomical, soiled, medicines, chemical, lab pre‑treated → incineration), red (contaminated plastics → autoclave + shred), white (sharps → puncture‑proof), blue (glass, metal implants). Storage ≤ 48 h; bar codes; no chlorinated bags.

Hospital IPC and occupational health

• HAI ≥ 48 h after admission: CAUTI, CLABSI, VAP, SSI. WHO 5 moments; ABHR 20–30 s. Standard + contact/droplet/airborne precautions. Bundles. Kayakalp 2015; NAP‑AMR 2017.
• Hazards: physical, chemical, biological, mechanical, ergonomic, psychosocial. Hierarchy: eliminate → substitute → engineer → administer → PPE.
• Silicosis (upper zones, eggshell calcification, ↑ TB); asbestosis (lower zones, plaques, mesothelioma); byssinosis (Monday tightness); bagassosis and farmer's lung (HP).
• Lead: colic, anaemia with basophilic stippling, Burton's line, wrist drop; BLL; no safe level; CDC child reference 3.5 µg/dL.
• 🆕 Four labour codes in force 21 November 2025 (OSH Code, Social Security Code, IR Code, Wages Code). ESI benefits: medical, sickness (70% × 91 days), maternity (26 weeks), disablement (90%), dependants', funeral, unemployment.