INTRODUCTION: 

All of us face a variety of risks to our health as we go about our day-today lives. Driving in cars, flying in planes, engaging in recreational activities and being exposed to environmental pollutants all pose-varying degrees of risk.

In the last several years, a growing body of scientific evidence has indicated that the air within homes and other buildings can be more seriously polluted than the outdoor air in even the largest and most industrialized cities. Other research indicates that people spend approximately 90 percent of their time indoors. Thus, for many people, the risks to health may be greater due to exposure to air pollution indoors than outdoors.

In addition, people who may be exposed to indoor air pollutants for the longest periods of time are often those most susceptible to the effects of indoor air pollution. Such groups include the young, the elderly, and the chronically ill, especially those suffering from respiratory or cardiovascular disease.

WHAT CAUSES INDOOR AIR POLLUTION?

Indoor pollution sources that release gases or particles into the air are the primary cause of indoor air quality problems in homes. Inadequate ventilation can increase indoor pollutant levels by not bringing in enough outdoor air to dilute emissions from indoor sources and by not carrying indoor air pollutants out of the home. High temperature and humidity levels can also increase concentrations of some pollutants.

POLLUTANT SOURCES:

There are many sources of indoor air pollution in any home. These include combustion sources such as oil, gas, kerosene, coal, wood, and tobacco products; building materials and furnishing as diverse as deteriorated, asbestos-containing insulation, wet or damp carpet, and cabinetry or furniture made of certain pressed wood products; products for household cleaning and maintenance, personal care, or hobbies; central heating and cooling systems and humidification devices; and outdoor sources such as radon, pesticides and outdoor air pollution.

However, indoor pollutant sources differ from house to house, urban to rural sector and country to country. Here the matter has been discussed in details on the above issues.

(WITH SPECIAL REFERENCE TO INDIA):

`POLLUTION' is now a catchy word of which air pollution is most debated. Whenever we speak of air pollution the immediate picture come to us about the problem related to outdoor pollution not Indoors pollution. This is because most of us believe home is our heaven. In our country air pollution particularly in rural households has so far been neglected. It is recently estimated that 82% of sulphusdioxide (SO), 38% of Nitrogendioxide (NO), 88% of volatile organic compound and 96% particulate matter emissions in the country come from the household sector. In India these high concentrations arise because unprocessed biofuels such as cowdung, fuel wood and crop residues are burnt within the kitchen. Mineral coal also causes much pollution in a few households. A silent majority of the population, namely poor women and children, continue to suffer from air pollution in the Indoor Environment.

Use of biomass fuels for cooking is the primary source of Indoor Pollution. "Such fuels are used by more than three quarters of Indian households and nearly half of the World’s Population relies on them", writes Kirk R Smith, Professor of Environmental Health Sciences at the University of California, Berkely, US, and expert on indoor air pollution. And unlike the highly visible pollution from vehicles or smokestacks, which is heavily diluted by the time it travels from the source to the air we breathe, domestic pollution due to biomass burning is inhaled much closer to the source, and in much higher concentrated levels.

Health effects of the polluted air indoors go hand-to hand with exposure. Biomass fuels, open chulhas and inadequate ventilation, all wreak havoc with the lives of two major vulnerable groups women and children, who spend large amounts of time within the home and experience the worst health effects due to indoor air pollution.

Particulates, as Smith Points out, are the "oldest" but still the "most important single class of air pollutants". According to an estimate made by him, out of a total of 8.2 million deaths in India in 1989, almost 0.9-3.6 million could be attributed to particulate air pollution. Concentrations of particulates found indoors according to available studies, often exceed the levels found outdoors. Considering the fact that people spend the maximum number of hours indoors in the developing nations, exposure to and the resultant negative impact on health from particulates constitute a notable threat.

Rural populations in developing nations bear the greatest burden of exposures to particulate matter. An average particulate concentrations of 551 ug/cum overwhelms rural homes in developing countries, which is shocking nine times higher that the corresponding levels in developed countries. In developing countries, indoor concentrations of particulate matter exceeds that of outdoors. Despite growing outdoor pollution due to vehicles and industries, urban concentrations of particulate matter are 278 ug/cum, which is 50 per cent lower than the rural indoor levels.

Particulate concentrations present indoors in rural homes of developing countries is equivalent to the entire world breathing 176 mg/cum. It is however not surprising that exposure to and the resulting negative impact on health from particulates constitute a significant threat.

It has been found that compared to modern cooking fuels like kerosene and liquefied petroleum gas (LPG), biofules generate 10-100 times more respirable particulates per meal owing to their low thermal and heat-transfer efficiencies. Biofuel combustion is also responsible for the emission of pollutants such as sulphur dioxide, nitrogen dioxide, carbon monoxide, total suspended particulates and polycyclic aromatic hydrocarbons.

Respiratory infections, one of the three major causes of infant mortality in India (the other two being diarrhoea and malnutrition), is a result of exposure to fine particulate matter both outdoors and indoors. Among adult women, chronic lung ailments and cor pulmonale are the common killers, while adverse outcomes of pregnancy and eye disorders constitute other significant problems.

 BLINDNESS:

Eye problems are not uncommon in India considering that one-third of global cataract occur in India. And cataracts are responsible for at lease 50 per cent of complete blindness worldwide. The finding of this research suggest that prevalence of blindness in India could be significantly reduced by decreasing people's exposure to smoke from biofuel combustion.

A 1977 study by researchers at the East-West Center in the US suggest that 18 per cent of blindness may be attributed to the use of biomass (wood, dung, crop residue) for cooking. This translates into 29 per cent of blindness in rural areas, and 6 per cent in urban environment. A case study of cataract patients at a New Delhi Opthalmic clinic showed that low-quality cooking fuels were significantly associated with three of the four major types of cataracts.

Researchers found that persons living in households using biomass as the primary source of cooking fuels had 1.24 times the rate of complete or partial blindness than those using cleaner fuels. Prevalence rates of partial blindness were 7,206 per 100,000 people in biomass using households compared to 5,489 per 100,000 people in households using cleaner fuels. The prevalence of partial blindness is about 10 times higher than that of complete blindness. Blindness and cataract are major health problems in India. Studies have indicated that cataract accounts for more than 80 per cent of complete blindness in India.

Biomass fuels are used for cooking by about three-quarters of the population. The proportion is almost three times higher in rural areas (93 per cent) than in urban areas (32 per cent).

NEONATAL IMMUNE SYSTEM:

Indoor air pollution can affect the immune systems of new borns, making them more susceptible to illness. A 1995 study of infants from tribal familieis in east India found that new borns exposed to indoor pollution had higher levels of gastro-intestinal tract and respiratory tract infections than unexposed infants. The presence of indoor air pollution was correlated with disturbance and depression of serum immunoglobulin levels in newborns, suggesting that their immune systems may be less able to combat illness in the future as well.

RESPIRATORY DISEASE:

About 15 million children fall prey every year to acute respiratory infections, the overwhelming majority being in developing countries. Of these, around one-third or 5 million children under the age of five die of respiratory disease every year in developing countries. Since respiratory disease is preventable and curable, this is especially disturbing. Levels of indoor air pollution are significantly correlated with acute respiratory infections in infants and must be studied as a risk factor in child survival.

In 1977, homes with wood-burning stoves in Delhi were found to have pollution levels which were 50 per cent higher (at 318 mg/cum) than those using kerosene. Infants in these homes had an annual average of 34 episodes of acute respiratory infections per 1000 child-weeks. Decreasing the amount of smoke exposure could prevent a great deal of respiratory infections. In 1977, the results of a study conducted in Nepal suggested that if all children were moved into the lowest smoke exposure group, upto 25 per cent of moderate and severe respiratory infections could be eliminated.

A study in Lucknow attempted to assess the association between air pollutants and respiratory symptom complexd in pre-school children during 1996. Respiratory symptoms complex includes running nose, cough, sore throat, difficulty in breathing, noisy respiration and wheezing. Even after controlling ambient pollutants, which are known to increase mortality rates, the risk of respiratory symptoms and its duration, pre-school children who remained indoors during cooking hours had double the risk of respiratory symptoms. Moreover, a linkage between respiratory symptoms complex and the use of dung, wood, coal and kerosene for cooking and heating has been established. This suggestes that although increasing ambient pollution levels are of great health concern, the health risks of biofuel combustion continue to be an independent risk factor for respiratory symptoms.

CHRONIC RESPIRATORY DISEASE:

Chronic or long-term exposure to respiratory irritants, namely, oxides of nitrogen sulphur dioxide and particulate matter, is believed to be the chief cause of respiratory damage. Studies conducted in early 1980s found a higher occurrence of chronic bronchitis and corpulmonale in rural women exposed to chulhas fuelled with cowdung cakes and firewood.

Even healthy women in rural areas have been found to have lower ventilatory capacity compared to urban females. Therefore, more research is necessary to determine whether chulha smoke is actually the cause of higher levels of respiratory symptoms as other factors such as recurrent respiratory infections during childhood, overcrowding, malnutrition and ambient air pollution could be responsible.

Studies done in the 1980s found similar association between chulha smoke and respiratory distress in urban populations. A 1996 study of 315 women using biofuels, kerosene and LPG (105 each) within an urban slum of Pondicherry concluded that 23 per cent of women using biofuels reported having respiratory symptoms (which were cough, cold, breathlessness or chest illnesses, which limited household activity for more than one week) as against 13 per cent of kerosene and 8 per cent of LPG users. 

While women in the Pandicherry study, who used kerosene and LPG, cooked for about three hours, biofuels users spent approximately four hours cooking each day. In addition, women who used biofuels spent a larger percentage of their cooking time near the stove. They reported spending about 37 per cent of cooking time infront of stove, compared to around 25 per cent for women who used other types of fuel (see Table). Both, the prolonged exposure to pollutants, and increased time spent in close proximity to the stove, could have a deleterious effect on their respiratory health. A negative correlation between lung functioning, duration of cooking and exposure has been observed elsewhere too.

CHRONIC OBSTRUCTIVE LUNG DISEASE:

Chronic bronchitis is predominantly affects males in the developed world. However, in developing countries, despite the fact that men smoke much more heavily than women, both groups are equally affected by chronic bronchitis. Exposure to biomass fuels in the home has been responsible for the additional burden of the disease in women. Their exposure to smoke in the domestic environment for several hours every day and over several years leads to pulmonary hypertension and cardiac enlargement, ultimately resulting in corpulmonale.

In fact, although 75 per cent of the males who suffer from chronic bronchitis are smokers compared to 10 per cent of women who smoke, the rate of corpulmonale among men and women in northern India is same. Researchers suggest that as nearly all women who suffer from chronic bronchitis use biofuels for cooking exposure to smoke was responsible for the increased prevalence of the disease in them. This also explains the earlier onset of disease in women, who may have been exposed to biofuel smoke much before men started smoking.

Tobacco smoke and wood smoke are similar mixtures in many ways. Suspected carcinogens in cigarette smoke, such as benzo (a) Pyrene and formaldehyde are also present in wood smoke! Assuming that an average smoker smokes around 40 cigarettes per day, the exposure of a person cooking with biofuels can be compared to both active and passive (second hand smoke) smokers. Active smokers inhale pollutants with every "PUFF", but a filter absorbs some of the toxins present. In contrasts, both passive smokers and people who cook with biofuels are exposed with every breath (see Table No. 2).

Until more epidemiological studies are conducted on the health effects of biomass combustion, information from literature on smoking and health can be used to get an idea about possible effects of domestic smoke exposure.

CANCER:

While no study is available in India to link domestic air pollution to cancer, studies have been conducted in China on the association between using coal as fuel and lung cancer. Research pinpointed many chemicals such as the potent poly-aromatic hydrocarbons in biomass smoke, which are known to cause cancer in test animals in laboratories. Further investigation of this association is necessary before any conclusions can be reached.

ADVERSE PREGNANCY OUTCOMES:

Although there is a lack of research focusing on adverse pregnancy outcome, a 1991 study in Ahmedabad had shown that women exposed to domestic smoke during pregnancy had one-and-a-half times the odds of still birth comkpared to mothers who were unexposed.

Indirect evidence suggests that increased carbon monoxide content, which occurs as a result of biomass burning, could lead to stillbirths, neonatal deaths or low birth weight. As documented in research on maternal cigarette smoking and birth outcomes, carbon monoxide limits oxygen delivery to haemoglobin of both the mother and the foetus. Considerable amounts of this undesirable gas has been detected in the bloodstreams of women cooking with biomass in India and Guatemala. Besides, studies conducted in Western India associate a 50 per cent increase in stillbirths to exposures suffered by the region's pregnant women.

MONITORING DOMESTIC AIR:

More than 60 per cent of the total worldwide exposure to particulates is attributable to biofuel combustion. However, enclosed spaces within the home are not systematically monitored by the Pollution Boards. In fact, a 1995 study conducted by the World Bank on the economy wide costs of air pollution did not consider the impact of indoor air pollution, supposedly due to absence of data in this field. The study did, however, acknowledge that "indoor air pollution, due to cooking and heating with biofuels, is potentially a large public health factor in both urban and rural areas". This is quite an understatement considering that 80100 per cent of daily exposure to air pollution is contributed by the indoor environments. In otherwords, if people are spending most of their time indoors, the quality of their indoor air has greater health consequences than the outside or ambient air.

Quality of air is often monitored in the occupational setting. This is important, since people spend about 40 hours per week at the workplace. However, for many women home is their occupational setting. Studies have revealed that women spend 80-100 per cent of their time indoors, hence, the quality of indoor air has greater health consequences than the outside air. While the World Bank study on health effects of air pollution estimated that around 40,000 deaths in India can be attributed to air pollution in 1991-92, a 1977 study by Tata Energy Research Institute (TERI), a Consultancy working in the area of energy, of total number of women using the fuel type which takes indoor levels of pollution into account puts the number of premature deaths each year at around 2.2 million.

In an essentially `back of the envelope’ study, the researchers considered fuels that emitted different levels of PM10 (different fuels emit different levels of PM10 - for example, bio mass such as dung, charcoal and wood emit upto 1.4mg/cum, while LPG emits only about 0.4 micro-gram/cum), for seven major activity-based groups of the Indian population (women workers, housewives, infants, male workers, elderly, School/College children and unemployed males). Among other things, the study concluded that 440 million asthma attacks could be attributed to PM10, annually (see Table No. 3).

APPROACH FOR SOLUTION OF THE PROBLEM:

Decreasing people’s exposure to domestic pollution involves three types of improvement - improved ventilation, stoves and fuels. But this is easier said than done. There are different Peoples Policies & Practices involved at every level of domestic pollution. Domestic pollution cannot be addressed without looking at the issues of women's empowerment. At the same time, a purely grass-roots approach, however, well-intentioned, will not be able to improve people’s overall health and well-being. Domestic pollution is an issue energy, social Justice as well as availability of resources. Educational programmes to promote increased ventilation, keeping children away from the kitchen during cooking or the use of improved chulhas will not address the underlying issues of willingness to change or access to less polluting fuels and cooking methods.

Cooking on chulhas results in pollutant emissions much higher than those recommended by National Ambient Air Quality Standards (NAAQS). On an average, chulha smoke contains 457.6 ug/cum of sulphur-dioxide, 118.4 ug/cum of oxides of nitrogen, and 2018.18-2544.5 ug/cum of SPM. This is especially alarming, given that sulphur dioxide and PM10 (the respirable or inhalable component of SPM) are the pollutants responsible for 95 per cent of the health impacts of air pollution.

Tests conducted within laboratory settings demonstrate that improved chulhas can decrease the levels of pollutants emitted.A study comparing the minimum emission value of the traditional chulha with improved chulhas, reports 96 per cent to 100 per cent decrease in sulphur-dioxide levels. In addition, oxides of nitrogen levels fell by 36 per cent and 48 per cent, while formaldehyde levels decreased to 32 per cent and 76 per cent below the minimum emission values for a traditional stove.

However, improved stoves are not likely to be the only cure of indoor pollution. Access to cleaner burning, processed biofuels should be the long-term goal. But chulhas do address the short-term goal of decreasing levels of pollutants emitted from biomass combustion.

Biogas technology, if properly implemented, also has the potential to free people from the ill effects of biomass smokes. Unfortunately, socio-economic conditions, such as low livestock ownership, is a constraint for many families. Dung availability is a major constraint for families, which do not own livestocks. The Ministry of Non-conventional Energy Sources (MNES) estimates that 12 million biogas plants, representing 10 per cent of the total rural households, could potentially be installed. However, as of 1995, only 18 per cent of this potential had been achieved. So unless and untill we can able to alleviate the poverty in the rural Sector we cannot achieve cleaner indoor environment rather it will detoriate further.