Post -by Gautam Shah
An Interior Space has finite volume, but with very average level of air exchange with outside environment. Interior spaces can support a moderate level of human occupation and of certain intensity but for fixed duration. In excessively polluted localities it cannot offer the comfort and health safety beyond a limited period.
Outside air is always fresher due to its infinite volume, air currents, solar radiation and other environmental processes of nature. Though external air in highly polluted surroundings could be inimical, during specific periods. For buildings, at micro climate level, the exterior air may be contaminated on specific sides and periods of the day.
Indoor air quality in buildings can be improved, by control at the source, by filtration techniques, and by passive and active means of ventilation to dilute contaminants. Inadequate exchange (ventilation) can increase indoor pollution level by not bringing in enough and quality outdoor air to dilute the pollutants in indoor air. High temperature, humidity levels and to some extent air movements also increase concentrations of some pollutants.
To refresh the interior environment, one needs passive and benign interaction with the exteriors. The benign interaction could be scheduled in terms of time, such as during periods when outside environment is better, or facilitating the exchange on faces that are less vulnerable to exterior fouling, such as off the road sides, terraces, etc.
Contamination of Interior Spaces is not related to occupancy, but it may continue in dormant periods also. Many of the contaminants evolve from building’s materials, furniture, furnishings, cleaning and maintenance products, and as after effects of processes (such condensation of vapours, deposition of airborne particles, bacterial growth, etc.). The contaminants include unwanted gases, excess moisture, volatile organic compounds (VOCs), odours, particulate matters, etc.
Poor indoor air quality can cause or contribute to the development of infections, lung cancer, and chronic lung diseases such as asthma. In addition, it can cause headaches, dry eyes, nasal congestion, nausea and fatigue. People, who already have lung disease are at greater risk.
Formaldehyde is a carcinogenic substance and also causes coughing, eye, nose, and throat irritation, skin rashes, headaches, and dizziness. It is a very common chemical group found in many substances such as adhesives, paints, dyes, processed and printed fabrics, carpets, upholstery, particle board, and plywoods. Formaldehyde continues to get released in the air. Similarly many types potentially harmful chemicals are emitted by household cleaning agents, personal care products, pesticides, paints, hobby products, and solvents. Such chemicals can cause dizziness, nausea, allergic reactions, eye, skin and respiratory-tract irritation.
Some simple strategies to improve Quality of Indoor Air
1 Design wise isolate areas of high contamination by controlled partitioning system from benign areas.
2 Recognize the role of cracks and crevices for micro ventilation in buildings of warm climates, compared with a tightly sealed entity designed to avoid heat loss in buildings of colder climates.
3 Schedule activities and locate processes in areas where passive exchange with the outdoors is available.
4 Interior Design must include products and processes with least or zero VOC emissions.
5 Use cleaning and maintenance products that emit low or zero VOCs.
6 Plan for Air Moisture Control by way of ventilation, diffusion and scrubbing.