In the last few decades, Indoor Air Quality (IAQ) has received increasing attention from the international scientific community, political institutions, and environmental governances for improving the comfort, health, and wellbeing of building occupants. Several studies on this topic have shown both qualitative and quantitative IAQ variations through the years, underlining an increase in pollutants and their levels. To this aim, IAQ-related standards and regulations, policies for non-industrial buildings, and monitoring plans have been developed in several countries. It has been estimated that people spend about 90 per cent of their time in both private and public indoor environments such as homes, gyms, schools, workplaces, transportation vehicles, etc. Thus, IAQ has a significant impact on health and quality of life in general. For many people, the health risks from exposure to indoor air pollution may be greater than those related to outdoor pollution. In particular, poor indoor air quality can be harmful to vulnerable groups such as children, young adults, the elderly, or those suffering chronic respiratory or cardiovascular diseases. Indoor environments represent a mix of outdoor pollutants prevalently associated with vehicular traffic and industrial activities, which can enter by infiltrations or through natural and mechanical ventilation systems, as well as indoor contaminants, which originate inside the building, from combustion sources (such as burning fuels, coal, and wood; tobacco products; and candles), emissions from building materials and furnishings, central heating and cooling systems, humidification devices, moisture processes, electronic equipment, products for household cleaning, pets, and the behaviour of building occupants (i.e., smoking, painting, etc.). IAQ can be affected by various chemicals, including gases (i.e., carbon monoxide, ozone, radon), volatile organic compounds (VOCs), particulate matter (PM) and fibers, organic and inorganic contaminants, and biological particles such as bacteria, fungi, and pollen. The large number of variables that impact IAQ inevitably leads to a wide range of studies and scientific papers published in journals from many kinds of scientific subjects (e.g., chemistry, medicine, environmental sciences, etc.). To further underline the importance of IAQ studies, the present special issue was published. It includes 22 contributions (Figure 1) by some of the main experts in the field of indoor air pollution in public and private buildings and related health concerns.
It is essential that the hazardous impacts from environmental pollution are regularly reported and monitored. Of the various kinds of pollution, the air pollution has attracted high priority in respect of environmental regulation since the environmental damage due to such pollution mostly affects human well-being directly by way of adverse health effects on the population exposed to it. Air quality has deteriorated in cities in India, a situation driven by population growth, industrialisation and increased vehicle use. Integrated air quality management (AQM), which is an evaluation and monitoring tool, is a challenge to carry out in most developing countries because of the lack of information on sources of air pollution and insufficient ambient air monitoring data that is available in the public domain.
Effects of Indoor Air Pollution on Health
The ill-effects of indoor air pollution result in about 2 million premature deaths per year, wherein 44 per cent are due to pneumonia, 54 per cent from chronic obstructive pulmonary disease (COPD), and 2 per cent from lung cancer. The most affected groups are women and younger children, as they spend maximum time at home (Figure 2). The morbidities associated with indoor air pollution are respiratory illnesses, viz., acute respiratory tract infection and COPD, poor perinatal outcomes like low birth weight and still birth, cancer of nasopharynx, larynx, lung, and leukemia.
The harmful health effects of formaldehyde range from being an acute irritant, reducing vital capacity, causing bronchitis, to being a carcinogen causing leukemia and lung cancer. The indoor air pollutants have potential health effects. The particulates cause respiratory infections, chronic bronchitis, COPD, and also lead to exacerbation of COPD. Sulfur dioxide and nitrogen dioxide cause wheezing and exacerbation of asthma. In addition to this, nitrogen dioxide causes respiratory infections and deteriorates lung functions. Sulfur dioxide has an additional etiological role in exacerbation of COPD and cardiovascular disease. The risk of poor perinatal outcomes, viz., low birth weight and perinatal death increases from exposure to carbon monoxide. Biomass smoke, especially, metal ions and polycyclic aromatics, leads to development of cataract. Polycyclic aromatic hydrocarbons lead to development of cancers of lungs, mouth, nasopharynx, and larynx. As a consequence of poverty, factors such as living conditions, sanitation, and access to water are associated with solid fuel use, and should be considered while measuring impact of solid fuel on child survival (Figure 3).
Public awareness: One of the most important steps in prevention of indoor air pollution is education, viz., spreading awareness among people about the issue and the serious threat it poses to their health and wellbeing. The education should help people in finding different ways of reducing exposures with better kitchen management and protection of children at home. People should also be educated about the use of alternative cleaner sources of energy to replace direct combustion of biomass fuel. The stakeholders must include not only public, but also politicians and administrators to ensure their commitment and increase their awareness about health effects of indoor air pollution.
Change in pattern of fuel use: Fuel use depends on ones’ habit, its availability, and most importantly, its affordability. At present, majority of low-income families rely solely on direct combustion of biomass fuels for their cooking needs as this is the cheapest and easiest option available to them; however, this could be rectified by promoting the use of cleaner energy sources such as gobar gas which utilses cow dung to produce gas for cooking.
Modification of design of cooking stove: The stoves should be modified from traditional smoky and leaky cooking stoves to the ones which are fuel efficient, smokeless and have an exit (e.g., chimney) for indoor pollutants. A good example is the one designed by the National Biomass Cook Stoves Initiative of the Ministry of New and Renewable Energy under a special project on cook stove during 2009-2010, with the primary aim of enhancing the availability of clean and efficient energy for the energy deficient and poorer sections of the country.
Improvement in ventilation: During construction of a house, importance should be given to adequate ventilation for poorly ventilated houses, measures such as a window above the cooking stove and cross ventilation through doors should be instituted.
Intersectoral coordination and global initiative: Indoor air pollution can only be controlled with coordinated and committed efforts between different sectors concerned with health, energy, environment, housing, and rural development.
Air conditioning systems: Many kinds of AC systems are used to improve indoor thermal comfort and IAQ. In this regard, current recent research is mainly focused on dedicated outdoor air system (DOAS), independent control of temperature and humidity system (ICTHS), desiccant assisted air conditioning (DAC) and cooling ceiling and displacement ventilation systems (CC/DV) to improve the indoor air quality.
Indoor air purification: Indoor air purification is an important method of removing indoor pollutants and improving IAQ under the circumstances that the ventilation and the control of pollution sources are impossible. The major methods of indoor air purification include filtration, adsorption, photo catalytic oxidation (PCO), negative air ions (NAIs), and non-thermal plasma (NTP).
Solar passive techniques in a house construction: The Solar Paneled Pyramidal Roof House constructed for a hot climate should take measures to reduce heat radiation inside the house by orienting house to minimum exposure in west and east and larger size window. Three windows of size 0.9 x 0.6 m and one window of size 1.2 x 0.6 m are provided. Apart from that, two ventilators are constructed honey combed brick work (with fly ash bricks) to allow the natural ventilation inside the house. This house roof is constructed in pyramidal shape to have minimum sunlight effect on the building. The total roof area of the pyramidal portion is 16.4 square meter with an angle of 38° inclination to the horizontal. The plinth area of the green house is 8.196 sqm.
Though evidence exists for increase in indoor air pollution in India and its association with both increased morbidity and mortality, there is still a need of further studies to assess the exposure levels of indoor pollutants and to further strengthen the evidence for their association with outcomes like tuberculosis, cataract, asthma, cardiovascular health, and cancers. At the same time, effective interventions, starting from education, change in fuel patterns, proper designing of stoves and houses, to a committed and determined intersectoral coordination towards promotion of public health is the need of the hour.
Dr. D.B. Jani
Government Engineering College, Dahod,
Gujarat Technological University – GTU, Ahmedabad