1. By Dr. Khalid El Tohami Introduction to Environmental Medicine (1)

2. At the end of the session the student should be able to: * Describe water supply and water pollution * Explain methods of purification of water * Enumerate environmental pollutants and hazards

3. * Environment : = The external factors (living – non living – material – non material) which surrounds man. * Descriptive classification: Physical: water, air, housing, etc. Biological: animal, plant, etc. Social: customs, income, etc. * Bad or poor environment leads to ill-health * Man responsible for pollution

4. * = The science of safeguarding health * N.S.F.(USA) definition: “Is a way of life, it is quality of living that is expressed in the clean home, clean farm, clean business, the clean neighborhood, and the clean community. Being away of life it must come from within the people, it is nourished by knowledge & grows as an obligation and ideal in human relations”

5. WHO definition: “ The control of all those factors in man’s physical environment which exercise or may exercise a deleterious effect on his physical development, health & survival.” * So now it called ENVIROMENTAL HEALTH * Its purpose is to create & maintain ecological conditions that will promote health & prevent disease * It is complex, needs a multi-disciplinary programme of action

7. * One of the essential public health care element is safe drinking water & sanitation. * Water is one of the physical component of the environment * It is not only a vital environmental factor to all forms of life, but has a great role in socio-economic development.

8. * Free from pathogenic agents * Free from harmful chemical substances * Free from color and taste * Usable for domestic purposes If not so we call it polluted or contaminated water

9. * Basic physiological requirement = 2 liters/head/day * Public health (domestic purposes) = 150-200 liters/head/day

10. 1. Domestic use 2. Public purposes 3. Industrial purposes 4. Agricultural purposes 5. Power production 6. Carrying away waste

11. Water source must be: a) Sufficient in quantity b) Acceptable in quality Three main sources: * Rain * Surface water Impounding Reservoirs Rivers & Streams Tanks, Ponds, & Lakes * Ground water Shallow Wells Deep Wells Springs

12. * Prime source of water * It has a cycle Characteristics: Physically : Purest water – clear –bright – sparkling Chemically: soft (only 0.0005 dissolved solids) Bacteriologically: from clean districts free from pathogenic agents

13. Impurities Dust – soot – microorganisms – carbon dioxide – nitrogen – oxygen & ammonia Acid rains ( gaseous sulphur – nitrogen oxide)

14. * Originate from rain water * Include : rivers, tanks, lakes, wades, sea, man made reservoirs * It prone to contamination so it never safe without sanitary protection & purification.

15. * Rivers: always grossly polluted unfit for drinking without treatment Characteristics: clear, turbid during rainy seasons, contains dissolved & suspended impurities of all kinds, high bacterial count including( human intest. Organisms), Impurities: from surface washing, sewage, industrial & trade waste, agricultural drainage, customs. Self-purification: dilution, sedimentation, aeration, oxidation, sunlight.

16. * Sea water: - Plentiful - Contains 3.5 % of salts in solution - Salt concentration of 30-36 g/liter of solids including chloride, sodium, magnesium - Desalting & demineralization is of high cost

17. * Rain water percolate into ground Advantages : - cheap - free from pathogens, - usually requires no treatment, - certain supply, - less subjected to surface contamination. Disadvantages: - hard, - require pumping

18. * Is the presence of offensive material in water. * May be natural or man made. * Industrial waste is a big problem in developed countries. * 70% of surface water is heavily polluted.

19. Natural pollutantsMan made pollutants Dissolved gases eg. Nitrogen, carbon dioxide, hydrogen sulphide Sewage (decompensated organic matters and pathogenic agents) Dissolved minerals eg. Salts of calcium, magnesium, sodium Industrial and trade waste (toxic agents, metal salts, organic chemicals) Suspended impurities eg. Clay, silt, sand, mud Agricultural pollutants (fertilizers, pesticides) Microscopic organismsPhysical pollutants ( heat, radiation)

20. * Water related diseases are human tragedies. * 2.3 billions in the world suffer from diseases related to water. * 60% of infant mortality are due to diseases related to water.

21. * On large scale - Storage - Filtration - Disinfection * On small scale - Household purification of water - Disinfection of wells

22. * during which some natural purification take place physical: impurities settle by gravity chemical: oxidation = decrease. ammonia & increase. nitrates biological: death of 90% of microorganisms in 5-7 days. (optimum=10-14)

23. * Slow sand or biological filters Simple, easy, cheap, high quality treatment * Rapid sand or mechanical filters Deals directly with raw water, less space, rapid, more flexible, easy washing

24. * Criteria of useful water disinfectant - powerful within time & not affected by water properties - no product of reaction - cheap, safe, with accurate application to water - property of leaving residual concentration - easy detectable by rabid simple techniques * Chlorination * Ozonation * Ultraviolet irradiation

25. 1. Household purification * boiling: * chemical disinfection: (bleaching powder, chlorine solution, hypochlorite, chlorine tablets, iodine, potassium permanganate) * filtration: 2. Disinfection of wells

26. Is the presence in the ambient (surrounding) atmosphere of substances (e.g. gases, mixtures, and particulate matter) generated by the activities of man in concentrations that interfere with human health, safety, or are injurious to vegetation and animals and other environmental media.

27. Sources of air pollution * Motor vehicles, especially in urban areas. They emit: -hydrocarbons, nitrogen oxides -carbon monoxide, lead, black smoke and malodorous fumes.

28. * Industries: * Smoke, sulphur dioxide, nitrogen oxides and ash * Hydrogen fluoride, hydrochloric acid, CO, CO2 * Domestic source: * Domestic combustion of coal, wood, or oil leading to smoke, dust, sulphur dioxide. * tobacco smoke “passive smoking” * Miscellaneous: * Burning refuse, incinerators, pesticide spraying, wind borne dust, * nuclear radiation, noise.

29. * Exposes more people to air pollutants than air pollution in outdoor air. * Women and young children have the greatest exposure (esp. in developing countries, rural areas) * It contributes to ARI in children, chronic lung disease and cancer in adults, and adverse pregnancy outcomes (stillbirth) * Studies revealed that improvement in indoor air quality :reduces ARI by 15% and reduces cancer by 10%.