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Local knowledge is critical for understanding toxic threats and sources of dangerous pollution. Here are some examples of risks to look out for:

• contamination of ground water by arsenic

• contamination of surface or ground water by chemical fertilisers

and pesticides, sewage, and waste materials

• accumulations of carbon monoxide emitted by vehicles,

generators, or stoves

• lead-based paints and glazes

• abandoned gem mines or mineral mines

• depleted uranium weapons

• dust raised by wind or vehicles

• acid from leaking batteries, particularly from vehicles

• oil leaking from vehicles, machinery, and storage facilities

• burning vegetation on the land, in yards, or in stoves for heat

and cooking (7.6.8, 7.6.9).

Further information on health and safety issues will be found in section 6.5.1; section 6.7 contains information on construction materials and finishes.

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Making food stores rodent-proof is particularly important. Buildings can be protected by closing all holes greater than 6mm in diameter: this is the smallest hole that a young mouse can enter. The holes should be blocked with strong material such as cement, mortar, or metal plates. Rats can chew through rope or light wire such as chicken wire.

A rodent-proof building will probably be monkey-proof as well, but primates are highly intelligent and, like racoons and a few birds, have been known to open doors and undo zip fasteners.

figure 6.3(b): rodent-proof building

rodent screen made around stilts from old tin cans

rodent screen made from flat stones on top of stilts

area under building kept clear so that rodents cannot climb up

Diesel is sometimes poured on the ground around the outside of tents to keep snakes at bay, but it needs to be reapplied frequently.

6.3.6 fire

Fire is a common hazard in transitional settlements. The risk is particularly high in dry areas where forest fires or wildfires are common, and in cold or temperate climates where cooking and heating stoves are used inside shelters.

Fires inside a building are generally started by people acting carelessly: for example, using a poorly designed stove, dropping a The dangers of malaria and other insect-borne diseases, including

sleeping sickness, dengue fever, yellow fever, leishmaniasis, and encephalitis, should be considered when selecting sites for transitional settlements. Mosquitoes, for example, tend to breed in stagnant or still water; so site managers are advised to fill in pits, remove discarded tyres and tins which could collect water, cover water-collection and storage facilities, and fill in potholes in roads and tracks. Mosquitoes can travel 3km or more from their breeding site, so you need to take into consideration a large area around the settlement.

Flies and rodents, such as rats, which can carry leptospirosis, can be tackled by proper management of waste and sanitation. Appropriate personal hygiene will reduce the risk of lice, fleas, and ticks taking hold in a settlement; this in turn will help to prevent diseases such as plague and rickettsial infections. Similarly, soil-borne diseases and parasites, such as anthrax, tetanus, ascariasis, and trichuriasis, cannot be eliminated from a settlement or area, but they can be avoided by paying attention to personal hygiene and proper food preparation.

Dust can become a disease vector: for example, by carrying faeces from fleas which have typhus. Planning for transitional settlement should consider how to reduce the spread of dust by wind, vehicles, and pedestrians.

Other vectors require more careful planning, or simply efforts to increase awareness of risks among the population. Monkeys are known to enter settlements and steal fruit or other food; they can carry hepatitis and possibly haemorrhagic fever viruses, such as Ebola or Marburg. Mammals such as monkeys and bats can carry rabies.

Due to the wide variety of diseases, vectors, and other threats, local knowledge is usually essential in order to identify the most prevalent threats and techniques of dealing with them (Thomson 1995).

buildings Treated mosquito nets (7.6.4) effectively protect sleeping people against mosquitoes. Additionally, mosquito nets or fine wire mesh can be stretched over windows and door frames to keep insects out. Some sprays are toxic to humans and other animals, so spraying should be conducted with care.

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define firebreaks

The need for firebreaks should be taken into account in all camp planning, and they should be installed in any self-settled camps as soon as possible. UNHCR standards for ‘Fire prevention’ are as follows.

66. As a rule of thumb a firebreak (area with no buildings) 30 m wide is recommended for approximately every 300 m of built-up area. In modular camps firebreaks should be situated between blocks. This area will be ideal for growing vegetables or recreation. If space allows, the distance between individual buildings should be great enough to prevent collapsing, burning buildings from touching adjacent buildings. The distance between structures should therefore be a minimum of twice the overall height of any structure; if building materials are highly inflammable (straw, thatch, etc.) the distance should be increased to 3 to 4 times the overall height. The direction of any prevailing wind will also be an important consideration.

UNHCR (2000), chapter 12, p.143

buildings For all transitional settlements, basic fire safety in building design needs to be observed. The longest distance to a fire escape should be no greater than 18m. This standard is based on average escape times from burning buildings. Extra time is required for vulnerable groups, and in buildings such as hospitals and schools. Fire exits should be planned, kept open, and clearly marked. Assembly points well away from the building should be identified and made known. Consider locating disabled people on the ground floor whenever possible.

figure 6.3(d): recommended (maximum) distance to a fire escape

Heat and flames kill and injure, but smoke and toxic gases are equally dangerous. Smoke and toxic gases can cause casualties outside the building as well.

Smoke from fires is dangerous not only in an emergency but in day- to-day activities, such as the burning of vegetation and dung in a building for cooking.

cigarette butt, failing to keep watch on burning embers or candles, not mending faulty electrical supplies or goods, and improperly using or storing flammable or combustible substances such as gasoline. Risk prevention and risk awareness are vital. External fires, such as wildfires, can be started by people, either through carelessness, or by trying to burn vegetation or rubbish; but they can also be started naturally by lightning.

Fire needs oxygen, fuel, and a high temperature to propagate itself. Removing any one of these ingredients will stop a fire. Oxygen can be removed by smothering the blaze: for example, by placing a specially treated fire blanket over a burning pot of grease. The temperature could be reduced by dousing the flames in water (depending on the type of fire).

settlements Planning transitional settlements with firebreaks helps to stop fires from spreading. Designing and locating settlements to reduce the impact of wind (6.3.10) can also help to reduce the spread of a large fire. Large settlements will require fire-fighting teams to be based within each compound. Consider providing water points and fire beaters at strategic points. Firebreaks alone generally do not stop a fire spreading: they merely slow it down and give time for fire-fight- ing teams to respond and for people to be evacuated.

As a rough guide, buildings should be twice as far apart as they are tall, in order to prevent fire from spreading from building to building (UNHCR 2000). Wind, however, can cause fire to jump large distances, particularly when flying embers are produced.

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settlements In earthquake zones, settlements should avoid alluvial plains, unstable slopes, steep slopes, unstable soils, or reclaimed areas where the ground has not been properly engineered. In earthquake zones it is important to be aware of areas liable to landslide, rock slide, avalanche, and liquefaction. Buildings should be spaced so that if one collapses it will not destroy another one. Such a layout will also help to avoid the spread of post-earthquake fires.

buildings Several techniques can be used to make buildings withstand earth- quakes better or, at least, to provide the occupants with a chance of escaping from the building or finding cover before it collapses:

• Stones should be used to tie walls together in rubble-masonry

construction.

• The building should be strongly secured to its foundation.

• For masonry, the building should be reinforced with timber or

concrete belts at different heights. Lintel levels are the best location for these.

• If the floor and roof are constructed of timber, it is good to

provide similar reinforcing bands at floor level and eaves level as well.

• Column lengths should be similar, so do not mix tall and short

columns.

• Do not use asymmetrical designs, such as ones that incorporate

wings or T-shaped, L-shaped, or H-shaped buildings.

• Buildings whose length is less than three times their width are

preferable, to keep the plan as square as possible.

• Avoid large and numerous openings; do not design openings

near to wall junctions.

• Long walls should be buttressed at intervals.

• Strong connections should be made where walls meet,

especially at corners: for example, by using vertical and horizontal reinforcement.

• Walls should be strongly connected to the foundation.

• Floor components should be strongly tied to each other; floor

joists should be strongly secured to walls.

• Roof components should be strongly tied to each other.

Warwick and Doig (2004) list the effects of daily exposure to smoke as follows:

• reduced effectiveness of the immune system

• increased rates of respiratory infections, including pneumonia,

particularly in children

• increased rates of other lung diseases, including lung cancer,

tuberculosis, and asthma

• low birth weight and increased infant mortality

• increased incidence of cataracts of the eye.

Reducing exposure to smoke should be a major goal when designing buildings in transitional settlements. Responses include the following (adapted from Warwick and Doig 2004):

• providing improved cooking devices, such as chimneys or

chimneyless, improved, biomass stoves

• providing alternative fuels for cooking, such as kerosene, liquid

petroleum gas, solar cookers, or electricity

• reducing the need for fire as a heat source, by providing more

efficient housing or using solar energy

• improving ventilation

• improving kitchen design and stove placement

• ensuring that stoves work appropriately, by maintaining them

properly

• encouraging people to avoid the smoke, for example by keeping

children away from it.