Green Living

Improve quality of indoor air

Environmental engineers therefore advise building owners to opt for balanced air filters and ventilation systems, dehumidifiers and appropriate solar shading.

Environmental engineers therefore advise building owners to opt for balanced air filters and ventilation systems, dehumidifiers and appropriate solar shading.  

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Outdoor air pollutants are impacting the indoor environment and builders have to take remedial measures, says M.A. Siraj

The ambient air quality in Indian cities has degraded to hazardous levels over the last two decades. People are exposed to extreme health risks due to increasing particulate matter, hazardous airborne agents in indoor spaces, emission of noxious gases from industries and automobiles and open sewerage systems. Outdoor air quality is affecting indoor air quality too.

Delhi, Patna, Gwalior, Raipur and Ahmedabad have been rated as the most polluted cities in India as far as air pollution is concerned. The World Health Organisation (WHO) designates any air that carries more than 10 microgram (i.e., a millionth of a gram) of pollutants in a cubic metre of air as hazardous.

The cities mentioned above show presence of pollutants 10 to 15 times more than the minimum. Compare them with Fresno, Riverside (both in Canada), Los Angeles-Long Beach, Hanford-Corcoran (both in California) and Fairbanks (Alaska) as the most polluted cities in the North American continent where presence of pollutants in air is two to five times higher than the minimum.

The main pollutants in urban air in India are particulate matter (i.e., dust, fine and ultrafine), industrial gases such as sulphur dioxide (SO2), nitrogen dioxide (NO2) and Ozone (O3), chullahs and open fire cooking and waste.

These airborne agents cause respiratory diseases such as asthma, acute bronchitis, allergy and irritation of the respiratory tract. They can even lead to cancer of the lung and bladder.

The International Agency for Research on Cancer, IARC, placed outdoor air pollution in Group 1 — a category used only when “there is sufficient evidence of carcinogenicity in humans.” Particulate matter, a major component of outdoor air pollution, was evaluated separately and classified as carcinogenic to humans.

Health effects caused by long-term exposure to fine particles, which is based on an annual standard, also include premature death, especially related to heart disease, cardiovascular effects such as heart attacks and strokes, reduced lung development, and development of chronic respiratory diseases such as asthma in children.

According to Maija Virta, managing director, Santrupti Engineers, a consulting firm on sustainable habitat, the end point of toxic risk is cancer. Quoting figures from the National Cancer Control Programme (NCCP), she says, “Seven lakh new cases of cancer are being detected in India every year and three lakh people are set to die every year.”

The NCCP forecasts that by 2026, more than 1.4 million people will be in the grip of the affliction.

The Programme has listed exposure to environmental carcinogens as one of the most important reasons and has recommended reducing environmental risk from all sources as the mitigation strategy.

The estimates from the United Nations Economic Programme (UNEP) put the number of deaths due to outdoor pollution worldwide at 3.5 million each year. Between 2005 and 2010 the death rate rose by 4 per cent worldwide, by 5 per cent in China and by 12 per cent in India. Cost of air pollution was estimated at $1.4 trillion in China and $0.5 trillion in India, according to a study by the Organisation of Economic Cooperation and Development (OECD). Translated into per capita terms, an average individual in India has to incur expenses to the tune of Rs. 25,000 annually on medical treatment for ailments caused by pollution or owing to wage losses due to absence from work.

Says Shankar Rajasekhara, Director-Engineering, IMPEC, air filtration is the ideal way to purify the indoor air quality (IAQ). He says a cubic metre of atmosphere carries 1.2 kg of air and an average individual inhales 20 kg of air every day. It is therefore imperative that indoor air quality is improved through purification and filtration as indoor quality of air is impacted by the outdoor air quality.

Other sources for indoor air pollution are tobacco smoking, copy machines and printers, cleaning products, moisture damages and growth of mould, paints, solvents and new furniture, perfumes and incense sticks and curiously, visitors.

Environmental engineers therefore advise building owners to opt for balanced air filters and ventilation systems, dehumidifiers and appropriate solar shading. Non-operational fans, pumps, fan coil units are to be removed and frequent servicing of H-VAC (heating, ventilation and cooling systems) has to be taken up.

Air-conditioning ducts have to be cleaned periodically. There are companies that deploy robots to penetrate deep and remove cobwebs and dust from these ducts.

Building owners are advised to adopt a holistic approach towards IAQ maintenance. Key IAQ measurements (e.g., temperature, velocity, particulate matter, CO2, SO2, NO2, O3) have to be obtained. Technical review of ventilation and cooling system must be sought and targets should be set in sync with professional advice.

The author can be contacted at maqsiraj@gmail.com

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Printable version | Jan 21, 2020 7:31:22 PM | https://www.thehindu.com/features/homes-and-gardens/green-living/improve-quality-of-indoor-air/article6891298.ece

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