The silent killer indoors

Muneera Parbeen

While the world screams about air pollution in our immediate environment, which poses severe risk to the physiological wellbeing of humans, little is said about similar hazards caused by pollution within the four walls of a home.

The topic of indoor air pollution is a topic that has somehow averted the attention of many environmentalists. A human being spends the longest period of his day within his house. Therefore, the lingering pollution within a house poses more immediate risk to his health. An individual could be exposed to more airborne substances indoors than he is outdoors.

There have been a few studies in the country itself on the ill effects of indoor pollution though a lot has been done on the topic even in neighbouring countries. At a seminar on air pollution, recently held in the city, Han Heijnen, an environmental health advisor to the WHO, Bangladesh, emphasised the issue saying that the hazards from indoor pollution is more acute than outdoor pollution, and stressed the need for its study.

Studies on the issue from the United States and Europe show that persons in industrialised nations spend more than 90 per cent of their time indoors. For infants, the elderly, persons with chronic diseases, and most urban residents of any age, the proportion is probably higher. In addition, the concentrations of many pollutants indoors exceed those of outdoors. The locations of highest concern are those involving prolonged, continuing exposure -- that is, home, school, and workplace.

Lungs are most vulnerable to airborne pollutants. Acute effects, however, may also include non-respiratory signs and symptoms, many of which depend on toxicological characteristics of the substances and host-related factors.

Heavy industry-related occupational hazards are generally limited to only those who work in that arena and are exposed to it directly in their course of work problems. Contaminants encountered at homes and offices are different from those encountered outdoors.

Experts say it is difficult to establish the actual causes of indoor pollutants because many signs and symptoms are non-specific, making differential diagnosis difficult. In many cases, multiple pollutants may be involved. The challenge is further compounded by the similar manifestations of many pollutants and by the similarity of those effects. These are usually allergies, influenza, and the common cold. Many effects may also be associated, independently or in combination with, stress, work pressures, and seasonal discomforts.

Because a few prominent aspects of indoor air pollution, notably environmental tobacco smoke (ETS) and "sick building syndrome," have been brought to the attention of the public, individuals usually think smoking alone is a big contributor to indoor pollution. While smoke from cigarettes is a big contributing factor, there are other apparently 'innocent' factors leading to health problems.

Key signs and symptoms of pollutants affecting the health of adults included pharyngitis, nasal congestion, persistent cough, conjunctival irritation, headache, wheezing (bronchial constriction) and exacerbation of chronic respiratory conditions. In children, the symptoms may be the onset of asthma, increased severity of, or difficulty in controlling, asthma, frequent upper respiratory infections, persistent middle-ear effusion, snoring, repeated pneumonia and bronchitis. In babies especially in our country, these symptoms are frequent and common, but never directly attributed to our living conditions.

Environmental tobacco smoke (ETS) is a major source of indoor air contaminants. The ubiquitous nature of ETS in indoor environments indicates that some unintentional inhalation of ETS by non-smokers is unavoidable. Environmental tobacco smoke is a dynamic, complex mixture of more than 4,000 chemicals found in both vapor and particle phases. Many of these chemicals are known toxic or carcinogenic agents. Non-smoker exposure to ETS-related toxic and carcinogenic substances will occur in indoor spaces where there is smoking.

All the compounds found in "mainstream" smoke, the smoke inhaled by the active smoker, are also found in "side-stream" smoke, the emission from the burning end of the cigarette, cigar, or pipe. ETS consists of both side-stream smoke and exhaled mainstream smoke. Inhalation of ETS is often termed "second-hand smoking", "passive smoking", or "involuntary smoking."

The role of exposure to tobacco smoke via active smoking as a cause of lung and other cancers, emphysema and other chronic obstructive pulmonary diseases, and cardiovascular and other diseases in adults has been firmly established. Smokers, however, are not the only ones affected.

The US Environmental Protection Agency (EPA) has classified ETS as a known human carcinogen and estimates that it is responsible for approximately 3,000 lung cancer deaths a year among non-smokers in the United States. Children's lungs are even more susceptible to the harmful effects of ETS. Experts say that in infants and young children up to three years, exposure to ETS causes an approximate doubling in the incidence of pneumonia and bronchitis. There is also strong evidence of increased middle ear effusion, reduced lung function, and reduced lung growth. Several studies in recent times have linked ETS with increased incidence and prevalence of asthma and increased severity of asthmatic symptoms in children of mothers who smoke heavily. The adverse health effects of ETS, especially in children, correlate with the amount of smoking in the home and are often more prevalent multiple adults smoke within a house. The impact of maternal smoking on foetal development has also been well documented in various studies around the world. Maternal smoking is also associated with increased incidence of Sudden Infant Death Syndrome.

Airborne particulate matter contained in ETS has been associated with impaired breathing, lung diseases, aggravation of existing respiratory and cardiovascular disease, changes to the body's immune system, and lowered defences against inhaled particles. For direct ETS exposure, measurable annoyance, irritation, and adverse health effects have been demonstrated in non-smokers, children and spouses in particular, who spend significant time in the presence of smokers. Acute cardiovascular effects of ETS include increased heart rate, blood pressure, blood carboxyhaemoglobin; and related reduction in exercise capacity in those with stable angina and in healthy people. Studies have also found increased incidence of nonfatal heart disease among non-smokers exposed to ETS, and it is thought likely that ETS increases the risk of peripheral vascular disease, as well.

With help from the Health professional's guide to ETS problems, USA

Source: The Daily Star, 5 October, 2001