Dampness and Inadequate Ventilation are Two Causes of Microbial Pollution

From the World Health Organization in its report WHO Guidelines for Indoor Air Quality: Dampness and Mould, published July 16, 2009

     The presence of many biological agents in indoor environments is attributable to dampness and inadequate ventilation. Excess moisture on almost all
 indoor materials leads to growth of microbes, such as mould, fungi and bacteria, whichsubsequently emit spores, cells, fragments and volatile organic compounds into indoor air. Moreover, dampness initiates chemical or biological degradation of materials, which also pollute indoor air. Dampness has therefore been suggested to be strong, consistent indicator of risk of asthma and respiratory symptoms (e.g. cough and wheeze). The health risks of biological contaminants of indoor air could thus be addressed by considering dampness as the risk indicator.

Several widely acknowledged global trends contribute to the conditions associated with increased exposure to dampness and mould:

►energy conservation measures that are not properly implemented (tightened building envelopes, ventilation deficits, improper insulation);

►urbanization (migration, building type and density, urban degradation, housing availability and social inequity);

►climate change (increasing frequency of extreme weather conditions, shifting of climate zones); and

►the quality and globalization of building materials and components, construction concepts and techniques.

These conditions increase the risks of adverse health effects due to biological contaminants of indoor air.