Environmental Health

1. Environmental Health KEMU 2014

2. SOIL • Upper layer of earths crust derived from disintegration of rocks and decay of animals and plants • Classified as Sand, Gravel, Clay, Humus, Reh, artificial soil • Sand- small sized particles • Gravel: large sized particles • Clay: fine grained earth • Humus: product of animal and vegetable decomposition in various stages of decaying containing high percentage of N2 • Reh: an efflorescence consisting of CO2, SO4, NaCL WITH Ca and Mg salts • Artificial Soil: when holes, grounds or other depressions are filled with rubbish, the resultant site is called manmade / artificial soil

3. Site: • should be dry • should not be filled in rainy season • rubbish should be deposited in layers not exceeding 6 feet and covered on all sides with at least 9 inches of earth • when entirely filled , should be a few feet above surrounding surface • land is used after 40 years • manmade soil is best used for agricultural purposes

4. Nitrogen Cycle • The steps by which N2 is excreted from the nitrates of soil and water incorporated as amino acid and protein in living organism and ultimately re converted to nitrates , constitute the Nitrogen cycle N2 • It is a vital process taking place in soil in disposal and utilization of organic matter • Organic protein buried in soil are decomposed by putrefactive bacteria from which amino acids are formed which are again broken into NH3 and CO2 • Co2 escapes from these compounds in atmosphere • Ammonia in soil is converted to NH4CL and NH4CO3

5. In soil, ammonia is oxidized by nitrifying bacteria into nitrates and then nitrites • Nitrites are taken up by plants which are in turn taken up by animals • If nitrites are found in soil water it indicates pollution and signifies active bacterial action and presence of organic matter. Nitrates alone are the indicator of past pollution only • Significance of Nitrogen cycle: • - organic decomposition • - purification of atmosphere • - fertilization power of soil increases • - (NO3) nitrate containing water is preferred

6. Carbon Cycle‘ The steps by which Carbon (in form of CO2) is extracted from atmosphere by living organisms and ultimately returned to the atmosphere , constitute the carbon cycle’ • Soil and Health : soil contains bacteria and spores eg. Vibrio cholera , salmonella and spores of anthrax and tetanus, worms eg. E histolytica • Soil deficient in iodine results in goiter • Due to organic overload , soil is polluted and results in soil dampness , which is associated with ill health

7. Housing • Housing is a physical structure providing protection and shelter and includes immediate surroundings and relating community services and facilities • WHO prefers to use the term ‘Residential environment’ i.e. a unit where the family can develop and flourish physically , mentally and socially . Also includes services, and facilities for the well being of the family and individual.

8. Climate and Health • Climate: average weather condition throughout a year at a place • Weather: a single event in series of conditions that make up the climate • Meteorology: science concerned with a phenomenon occuring in the environment the elements of meteorology are: • - atmospheric pressure • - air temperature • - humidity • - air velocity • - rainfall • - clouds • - sunshine

9. Atmospheric pressure : at earths surface close to sea level averages 760mmHg . falls as altitude increases and rises as altitude decreases determined by a Barometer • Effects of High Altitude: as altitude increases , atmospheric pressure decreases. This in turn decreases O2 so Hb concentration increases and the heart rate increases too. • Air is less dense at high altitude so partial pressure of oxygen is less. Man cannot survive at an altitude of 25000ft without assisted breathing. When there is sudden exposure to high altitude , following conditions occur: • - Acute Mountain Sickness: characterized by headache, insomnia, nausea, breathlessness , vomiting, impaired vision , tinnitus, palpitation and nose bleed • - High Altitude Pulmonary Edema: initially symptoms are of acute mountain sickness, gradually pts. Develop cough, Cheyenne stokes breathing, confusion and hallucinations. Treatment is to bring the pt. to lower altitude as soon as possible.

10. Effects of Low Altitude • Atmospheric pressure increases by 1 ATM for every 33 feet depth below sea level. This effect is seen in persons working in compressed air chambers or mines: • - Caissons Disease: at high pressure in depth, the gases in air are dissolved in blood. Excess concentration of N2 exerts a narcotic action leading to loss of mental functions. Excess of CO2 increases the action of N2 and leads to convulsions and death. Initial symptoms are fever, tachypnea, bradycardia, fatigue, weakness and hemorrhages.

11. Heat Stress • Effects of heat stress include: • - heat stroke • - hyperpyrexia • - Heat Exhaustion • - Heat Cramps • Heat Stroke: Failure of heat regulating mechanism • Clinical Features: include high body temperature, delirium, convulsions and partial or complete loss of consciousness, dry and hot skin • Death can ensue due to Hyperkalemia • Treatment: includes cooling off the pt. in ice water bath until rectal temperature falls to below 103 F. chlorpromazine is recommended along with rest for several days.

12. Cold Stress • Caused by intense or prolonged exposure to cold • Clinical features include: initial rise and then fall in body temperature, decreased pulse , BP and resp.rate, decreased GFR, shivering, muscular weakness, loss of sensation, numbness, coma and death

13. Solid Waste Disposal • Refuse/waste: term applied to unwanted or discarded waste material from houses and commercial, industrial and agricultural operations. • Sources: • - Street Refuse: collected from streets by cleaning services or scavenging eg. Leaves, paper, straw • - Market Refuse: consisting of animal and vegetable matter • - Industrial refuse: collected from industries ranging from completely inert material eg. CaCO3 to highly toxic waste • - Domestic Refuse: consisting of ash, rubbish and garbage

14. Methods of Refuse Disposal • 1. Dumping: easy . Refuse is dumped in low lying areas and as a result of bacterial action , refuse decreases considerably in volume and is converted to humus • - disadvantages: refuse is exposed to flies and rodents, may be dispersed by wind, is a source of noxious smell and unsightly and drainage from dumps may pollute ground water .WHO condemns dumping as most unsanitary method • Dumping method has now been improved and ‘composting’ is practiced. It has shown that breaking down of cellulose etc. is due to action of fungi and aerobic bacteria but these organisms require combined nitrogen and phosphate and alkaline reaction for their activities. Nitrogen can be supplied by cow dung and urine for these organisms to be activated , as a result of which ‘humus’ or ‘compost’ is formed. • Procedure: • - rubbish is placed in piles 6 ft. wide at the base and 4 ft at top and 2 ft high. Glass, earthenware and stone etc. are separated

15. 2. Controlled tipping: • Refuse is dumped in layers of six feet in depth and covered with a layer of earth to exclude air so that it will decompose without causing a nuisance. The tip should be protected by screens so that light articles like paper and dry leaves cannot be blown out . When one layer settles another is deposited.

16. The pile is trenched along the top and in this trench night soil emulsion is supplied before the trench in the pile is closed • Emulsion to the rubbish pile is applied daily for two weeks till the pile is moist n then every third day…interval depends upon weather conditions. If it rains , increase the strength of emulsion and decrease the rate of application. • When rubbish is a brown humus mass, remove half of the pile and the other can be mixed with raw rubbish and the process starts afresh • 3. Burial of Refuse: done in long trenches, under a layer of earth . Usually done to dispose off organic matter

17. Incineration: • Most satisfactory method, although costly • Where employed, the provision of a modern incinerator (with intelligent stoking) is the chief requirement for complete sterilization of refuse • The difficulty in connection with incineration is the greatly varying character of the refuse to be destroyed • Town refuse can be disposed off in a destructor

18. Collection ,Removal and Disposal of Human Excreta • To place the collection and disposal of human and animal excreta under proper control is one of the first principles of practical sanitation. Various methods used for disposal include: • - Conservancy Systems: In places where , for want of funds, water carriage system cannot be installed i.e. the excreta cannot be carried from the premises by means of sewers , it must be removed otherwise. System has to be efficient otherwise the open excreta can be a health hazard. • - : commonest method employed for collection and disposal of excreta in villages is use of open fields – most unhygienic, unaesthetic and devoid of civic sense

19. Sanitary Latrines : A good latrine need not necessarily have modern sanitary ware, the aim should be to have good maintenance and daily disinfection • The different types of latrines are • - Well or pit latrine • - Bore hole latrine • - water seal type of latrines • - trench latrines

20. Sewered Areas • Designed as water carriage system and sewage treatment • 1. Primary Treatment: • a) Screening: sewage is passed through a metal screen that intercepts large floating objects. Screens can be fixed or moveable and are removed from time to time and refuse is disposed off by burial or trenching • b) Removal of Grit: the grit chambers allow the settlement of heavier solids such as sand and gravel while permitting organic matter to pass through • c) sedimentation: sewage is made to flow through sedimentation tanks at velocity of 1-2 ft/sec. Process involves the separation of solids which can settle down from the liquid portion of sewage and removal of sedimented material. 50-70% of solids settle down here under the influence of gravity and is called sludge.

21. 2. Secondary treatment: include • - a) Artificial Biological Method: can be done by • - Percolating Filters: these consist of circular beds or stones from 5-6 ft deep and up to 200’ diameter, built of clinkers and stones. the effluent after the primary treatment is sprinkled uniformly on the surface of the bed. Bacteria are plentiful in the sewage. In passing through the filter, the sewage rapidly coats the filtering medium with a gelatinous growth of bacteria. When sewage flows over this bacterial growth , the organic matter is adsorbed from the sewage so that the result is a purified effluent. • - Activated Sludge Process: (bio aeration) this is a biological process in which raw sewage is mixed with activated sludge, resulting in flocculent coagulation of the suspended and dissolved solids and colloidal matter aiming at complete clarification of sewage..

22. In both the activated sludge process and the percolating filters , biochemical changes take place under aerobic conditions but the difference is that in the contact beds and filters the effluent passes over clinker and gravel and takes up oxygen but in activated sludge , jets of finely divided air are forced through the sewage , resulting in oxidation of sewage • Advantages of Activated Sludge Process: • - the effluent is fully oxidised, is clear and free of colloids and will not create nuisance if disposed off without further treatment • - no offensive odour as there is no septic decomposition • - the sludge has a high nitrogen value and therefore can be used as a manure • - plant installation requires small space and a skilled attendant with a small staff can easily manage it • - gas produced as a by product can be used for generating electricity

23. 3. Sludge Disposal: all methods of sewage disposal except broad irrigation result in the formation of large quantities of sludge which contains a very large proportion of water. • Since sludge is rich in nitrogen and phosphates, it can be utilized as a valuable manure provided the water can be gotten rid off. • it is therefore dewatered by air drying on sand beds, filtering, centrifuging, floatation and spraying. At times sample places of barren land has been brought under cultivation by irrigation with activated sludge effluent and sludge. • Sludge is scraped from the bottom of sedimentation tanks and pumped into digesters wherein gas is formed and the balance sludge is converted into dry cakes.