Housing conditions have greatly improved in the affluent industtrial nations throughout the second half of the twentieth sentury, but more than thirdds of the house holds in the world are in developing countries, the great maajority of them in rural areas; the most prevalent indoor environment in the world is the same now as throughout history—huts in rural communities. But this is changing. Urbanization is rapidly transforming the distribution of populations in the developing world. , where the proportion living in urban areas rose from less than 25% to over 33% between 1970 and 1985; by 2025, if present trends continue, the proportion living in urban areas in the developing world is expected to exceed 50%, and in the world as a whole the urban population will comprise 65% or more. Many cities will be very large (see Table 70-2, chapter 70)
Many of these new urban dwellers have terrible living conditions. In the last 20 years there has been a great increase in the numbers of people living in periurban slums in developing countries. They often lack sanitation, clean water suplies , acces to health care, and other basic such as elementary education. The proportion of people in such circumstances ranges between 20% and over 80% in most cities throughout Africa, Latin America, and South, South-east and South-west Asia. The plight of children is especially deplorable; infant mortality rates exceed 100 in many places. Children are often abandoned by parents who cannot provide for them and must fend for them selves from ages as young as 5 or 6 years; many turn to crime and child prostitution to survive.
These shanty-towns and periurban slums endanger the health and security of many millions in Latin America, Africa, and many parts of Asia. Accurate numbers are impossible to obtain because the missing services include enumeration by census-takers and because situations change so rapidly, but in mexico City, Lima, Santiago, Rio de Janeiro, Sao Paolo, and Bogota, well over half the total population live in the periurban slums. In the mid-1980s, there were as many as 30 million periurban slum-dwellers in these six cities alone. Others are even worse off: worldwide, an estimated 100 million people are entirely homeless, living on the streets without possessions, often from infancy onward. Although this is a problem mainly in developing countries, homeless people have increased in number in the most affluent industrial nations in the last decade, often forced out of their homes by hard economic times. Public health departements in large cities such as New York and London have been obliged to spend increasing proportions of their budgets on emergency shelter for growing numbers of homeless destitute families.
Increasing numbers, an estimated 15 million in 1989, live in refugee communities in Africa and the Middle and Far Eastwhere housing conditions are equally deplorable, sometimes worse than in periurban slums. Refugee communities may have health services, but these are seldom adequate; supplies supplies and continuity of services are often precarious; the safety and security of the inhabitants is often threatened by hostilities, and their long-term prospects for a better life are poor.
Industrially developed nations are experiencing other challenging new health problems related to housing conditions. Rising land values and the need to provide cheap housing for expanding populations have led to proliferationn of high rise, high-density apartment housing. Publicly supported housing projects economize by restricting living space and providing few amenities. This kind of dwelling creates new sets of problems: emotional tensions attributable to living too close to the neighbors, inadequate play areas for children, poor services, and defective elevators and communal washing machines. Only a small minority of people, predominantly the edicuated professional classes (such as many readers of this book), enjoy comfortable, aesthetically pleasing, healthy living conditions.
INDOOR ENVIRONMENT
Indoor climate and indoor air pollution, biological exposure factors, and various physical hazards encountered inside the home are encompassed by the term indoor environment.
The indoor climate maybe the same that out of doors, or it may be modified by heating, cooling, or adjusment of humidity levels, and often in sealed modern buildings, by all of these.
Physical hazards. Physical hazards in the indoor environment include toxic gases, respirable suspended particulates, asbestos fibers, ionizing radiation, notably radon and “daughters,” nonionizing radiation, and tobacco smoke.
Indoor air maybe contaminated with dusts, fumes, pollen, and nicroorganisms. The principal indoor air pollutants in industrially developed nations are summerized in Table 38-1. Many of these pollutants are harmfull to health. Some occur mainly in sealed office buildings, and others, such as tobacco smoke, in private dwellings.
In developing countries, indoor air pollution with products of biomass fuel combustion is a pervasive problem (Table 38-2). The fumes from cooking fires include high concentrations of respiratory irritants that cause chronic obstructive pulmonary disease (COPD) and that sometimes contain carcinogens too. Premature death from COPD is common among woman who from their childhood have spent many hours every day close to primitive cooking stoves, inhaling large quantities of toxic fumes.
The toxic gases specified in Table 38-1 come from many sources. Formaldehyde is emitted as an off-gas from particle board, carpet adhesives, and urea formaldehyde foam insulation; it is a respiratory and conjunctival irritant and sometimes causes asthma. It is not emitted in sufficient concentrations to constitute a significant cancer risk. Although rats exposed to formaldehyde do demonstrate increased incidence of nasopharyngeal cancer, there is only weak evidence of elevated cancer incidence or mortality rates even among persons occupationally exposed to far higher concentrations than occur in domestic settings. Nonetheless, ureaformaldehyde foam insulation has been banned in many jurisdictions on the basis of the evidence for carcinogenicity in rats. Gases and vapors from volatile solvents, such as cleaning fluids, have diverse origins. There is a wide range of other pollutants, such as many organic substances, oxides of nitrogen, sulfur and carbon, ozone benzene and terpines. All such toxic substances can be troublesome, especially in sealed air-conditioned buildings and most and most of all when the air is recirculated to conserve energy used to heat or cool the building. In combination with fluorescent lighting, these gases and suspended particulate matter can produce an irritating photochemical smog that may cause chronic conjunctivities and nasal congestion.
Imperfect ventilation can become a serious hazard if it leads to accumulation or recirculation of highly toxic gas such as carbon monoxide; this is especially likely when coal or coke is used as cooking or heating fuel in cold weather and vents to the out side are closed to conserve heat.
Asbestos was used for many years as a fire retardant and insulating substance in both domestic and commercial buildings. Its dangerous to health have led to restriction or banning of its use and to expensive renovations aimed at removing it. Fibrous glass insulation may present hazards similar to those of asbestos but less severe.
Ionizing radiation, in particular radon and “daughters”, can be a health hazard, especially if houses are sealed and air recirculated, in wich case there is greater opportunity for higher concentrations to accumulate. Sources of radon include trace amounts of radioactive material incorporated in cement used to construct basement. Radon can also be emitted from soil or rocks in the environment where the houses are built.
Nonionizing radiation, notably extremely low frequency electromagnetic radiation (ELF), has attracted much attention since the observation of cancer incidence at higher rates than expected among children living close to high voltage power lines. No convincing relationship has been demonstrated between childhood cancer and exposure to ELF from domestic appliances, with the possible exception of electric blankets. Microwave ovens and television screens are safe. The nature of the relationship, if any, between ELF and cancer remains controversial, however.
Tobacco smoke is often the greatest health hazard attributable to physical factors in the indoor environment. Infants and children are significantly more prone to respiratory infections, and nonsmoking spouses are more prone to chronic respiratory illnesses and to tobacco-related respiratory cancer when living in same house as a habitual cigarette smoker. Cigarette smoking is a hazard in another way as well: about 20% to 25% of deaths in domestic fires are a result of smoking.
Table 38-1. SOURCES AND POSSIBLE CONCENTRATONS OF INDOOR POLLUTANTS
Pollutant | Sources | Range of concentrations |
Respirable particles | Tobacco smoke Stoves Aerosol sprays | 0,05-0,7 mg/m3 |
Carbon monoxide | Combustion equipment Stoves, gas heaters | 1-115 mg/m3 |
Nitrogen dioxide | Gas cookers Cigarettes | 0,05-1,0 mg/m3 |
Sulfur dioxide | Coal combustion | 0,02-1 mg/m3 |
Carbon dioxide | Combustion Respiration | 600-9000 mg/m3 |
Formaldehyde | Particle board Carpet adhesives Insulation | 0,06-2,0 mg/m3 |
Other organic vapors (benzene, toluene, etc) | Solvents, adhesives, resin products, aerosol sprays | 0,01-0,1 mg/m3 |
Ozone | Electric arcing, UV light sources | 0,02-0,4 mg/m3 |
Radon and “daughters” | Building materials | 10-3000 Bq/m3 |
Asbestos | Insulation, fireproofing | 1 + fiber/cm3 |
Mineral fibers | Appliances | 100-10.000/m3 |
NOTE: tobacco smoke, benzene, radon and daughters, asbestos, and possibly formaldehyde are carcinogens; most others on this list are respiratory, or conjunctival irritants. Carbon dioxide is an asphyxiant, carbon monoxide is a lethal poison.
TABLE 38-2. INDOOR AIR POLLUTION FROM BIOMASS FUEL COMBUSTION DEVELOPING
| SPM [mg/m3] | BaP [mg/m3] | CO [mg/m3] | NO2 [μg/m3] | Other |
Nigeria, Lagos | - | - | 1076 | 15.168 | SO2, 38 ppm Benzene, 86 ppm |
Papua New Guinea | 0,84 | - | 35,5 | - | HCHO, 1,2 ppm |
Kenya Highlands | 4,0 | 145 | - | - | BaH, 224 μg/m3, Phenols, 1,0 μg/m3, Acetic acid, 4,6 μg/m3 |
India, Ahmedabad Cattle dung Dung and wood | 16,0 21,1 | 8250 9320 | - - | 144 326 | SO2, 242 μg/m3 SO2, 269 μg/m3 |
India, Gujarat | 2,7-10 | 2220-6070 | | | |
Monsoon | 56,6 | 19300 | | | |
BaP= Benz-a-pyrene; SPM= suspended particulate matter.
Data from de Konng et al., 1985, WHO: Air Quality Guidelines. Regional Reports series 23. Copenhagen: WHO, 1987.
Biological Hazards. Biological hazards in indoor environment include many varieties of pathogenic microorganisms. Mycobacterium tuberculosis survives for long periods in dark and dusty corners. Legionella lives in air conditioners, water-cooled stalls, for example. Mites that live on mattresses, cushions, and dusts infrequently swept floors cause asthma, as may many organic dusts and pollens. Many other infections, especially those spread by the fecal-oral route, occur most often when homes are dirty, verminous, or rat infested. Food storage and cooking facilities should be kept scrupulously clean at all times because many varieties of disease-carrying vermin are attracted by filth and because food scraps can be an excellent culture medium for many pathogens that cause food poisoning or other diseases.
Socioeconomic Conditions. Socioeconomic conditions are related to the quality of housing in many ways, some already alluded to. Crowding always tends to be greater among the poor than among the rich; this increases risks of transmitting communicable diseases and often imposes additional emotional stress that probably contributes to domestic violence. Street accidents involving children are more common in poor than wealthy neighborhoods because the children often have no other place than the street to play. Poor people generally live in poorly equipped and maintained homes, adding to the risk of domestic accidents ranging from falls down poorly lit stairwells to electrocution. Lead poisoning is a particular hazard for children in dilapidated houses where they are likely to ingest dried out flakes of lead-based paint. Emissions from factory smelter stacks contribute to environmental lead and other toxic metal contamination, also more often present in poor than in well-to-do neighborhoods, because the former are more often located in or close to heavily industrialized areas.
HOUSING CONDITIONS AND MENTAL HEALTH
Many descriptive studies by social epidemiologists and psychiatrists have demonstrated a consistent association between mental disorders and urban living conditions.9 There is also a close relationship between mental health and social class.10 Those who cannot cope with the competitive pressures of industrial and commercial civilization because they suffer from such disorders as schizophrenia, alcoholism, or mental retardation and have inadequate family and social support systems drift downward to the lowest depths of the slums or become homeless street people. There are estimated to be between 500.000 and 2 million homeless mentally ill persons in the United Stades.11 Schizophrenia and alcoholism have maximum prevalence in slums and skid row districts, and depression, manifested by attempted and accomplished suicide, is clustered in neighborhoods where a high proportion of the people live in single-room rented apartements.12 Behavior disorders such as adolescent delinquency, vandalism, and underachievement at school have high prevalence in dormitory suburbs occupied mainly by low-paid workers, where recreational facilities for young people are often inadequate and school are often of inferior quality. Bad housing does not cause these problems; they are usually symtomps of more complex social pathology. A different set of factors contribute to the syndrome called “suburban neurosis,” which occurs among women who remain housebound for much of the time while their husbands are at work and their children are at school13; this condition has been alleviated by television, which by bringing faces and voices into the house relieves loneliness.
HOUSING STANDARDS
Public health workers are directly concerned about the quality of housing because of the many ways it can affect health. Local health officials have special power to intervene when health is threatened by inadequate housing conditions. A handbook frequently revised by the Centers for Diseases Control and the American Public Health Association, Housing and Health; APHA-CDC Recommended Minimum Housing Standards,14 sets out specific detail on basic equipment and facilities, fire safety, lighting, ventilation, thermal requirements, sanitation, space requirements (occupancy standards), and special requirement for rooming houses. This valuable reference spells out general guidelines that can be used by local authorities as the basis for regulations, but there are no universal legally enforcible standards until local jurisdictions introduce them. Health Principles of Housing,15 a WHO manual, gives guidance on a wide range of behavioral factors that can influence health in relation to housing conditions, for example, by providing guidelines on ways to reduce psychological and social stresses by ensuring privacy and comfort and on the housing needs of populations at special risk such as pregnant women, the handicapped, and the elderly infirm. Both these booklets should be part of the library of every local health officer.
STATISTICAL INDICATORS OF HOUSING CONDITIONS
Health planning requires every kind of information pertinent to community health, including statistics on housing conditions. Useful information is routinely collected at the decennial census on density of occupancy (persons per bedroom), cooking and refrigerating facilities, and sanitary conditions. Perusal of tables showing these and other housing statistics enables health planners to identify neighborhoods at high risk of diseases associated with crowding and poor sanitation.
Census tables also enable health planners to identify less obstrusive health hazards, such as proportions of elderly persons living alone, whether in small apartments or multiple-room dwellings that perhaps were once the family home before all the others in the family moved away or died, leaving an elderly person as sole resdident. Once such neighborhood are identified, public health nurses and other community health workers can more easily locate the individuals at risk, who may need but have not yet asked for help.
In addition to census tables, there are other useful sources of information on neighborhoods with a high incidence of social pathology. Fire department record false alarm and fire deliberately lit; police department record details of vandalism and call to settle domestic disturbances, and school record absenteeism and truancy. All can be analyzed by area, thus pint-pointing high-risk neighborhoods; this method has been used as part of a program aimed at improving the chances of getting a goodstart in life for the children from disadvantage homes. There is a high correlation between these indicator of social pathology in a neighborhood, such as a high rise , high density apartment complex for low –incomes similar behavioral upsets among young and teenaged children.16
HEALTHY COMMUNITIES AND HEALTHY CITIES
As part of the initiated for “Health for all by the year 2000” that followed resolutions passed at the World Health Assembly in 1977,17 health planners in many nations, notably in European Region of WHO, began active planning for health promotion (to be distinguished from disease prevention). Health promotion (see Chapter 1) requires action many individuals and groups not usually identified with care of the sick or prevention of disease. The definition of health promotion, “the process of enabling people to increase control over and improve their health,” implies that people may often have to take action aimed at improving their living conditions. The Healty Cities movement is a coordinated program involving community health workers, local elected official in urban affairs, and a wide variety of community groups who collectively seek to upgrade living conditions. Initially, some of participating cities were relatively healthy place to live (e.g., Toronto, Canada) while others, (e.g., Liverpool, England) were not. The Healthy Cities initiative emphasizes activities that could be expected to enhance good health, such as provision of improved recreational facilities, services for children and their mothers (including basic education for the mothers as well as the children), and aggressive action to eradicate urban wasteland, industrial pollution, toxic dump sites, and other forms of urban blight.18 From modest beginnings the Healthy Cities movement has spread all over the world, and in some places has extended beyond cities to embrace rural communities.19 Since the environment in which people live, grow, work, and play so manifestly influences their health and happiness, the Healthy Cities initiative is potentially among the most valuable means at our disposal to make this environment healthful.
SPECIAL HOUSING NEEDS
Elderly and handicapped people require accommodation that has been adapted to enable easier access (ramps, handrails, wide doors to permit passage of wheelchairs), to facilitate storage and preparation of food (low-placed cupboards and stoves with front-fitted switches, which are inadvisable in homes where there are small children), and with special equipment for bathing and toileting (strong handrails, wheelchair access). Special accommodation of this type is often segregated, which tends to set the occupants apart in an urban ghetto for the elderly and handicapped. Integrated special housing is preferable, as examples in Denmark, Sweden, and the United Kingdom have demonstrated; in this setting, elderly, infirm, and younger handicapped persons live among healthy families, which many of them prefer and which helps to accustom healthy people to making allowances for their less fortunate fellow-citizens.
CONCLUSION
This is a brief summary of a complex and diverse field. The essential requirements of the domestic environment have been stressed, along with some of the obvious adverse effects of unsatisfactory housing.
The home should provide more than mere shelter and a safe place to raise children. It should be the setting in which the family lives and grows together, where bonds of affection and mutual trust are formed and strengthened, where socialization into the prevailing culture and intellectual stimulation are occurring, and where privacy is available when it is wanted and needed. Doxiadis20 coined the term ekistics, meaning the science of human settlements, to encompass the many interactive factors that make living space compatible with good physical, mental, emotional, and social health and well-being. The arrangement of dwelling units, their relationship to the natural and to the manmade environment, and their interior structure and function all play a part in creating a housing environment conducive to good health. Many less easily described and unmeasurable factors, such as the innumerable ways that people can interact, also contribute to the ambience of the living space. These intangible factors would receive more attention in a better world than this if we were really intent on applying all possible means to the end of promoting and preserving the public’s health. 