The Environmental Dangers of Indoor Dampness

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

Indoor environments contain a complex mixture of live (viable) and dead (nonviable)microorganisms, fragments thereof, toxins, allergens, volatile microbial organic compounds and other chemicals.

The indoor concentrations of some of these organisms and agents are known or suspected to be elevated in damp indoor environments and may affect the health of people living or working there.

In particular, it has been suggested that dust mites and fungi, both of which favour damp environments, play a major role. Dust mites and several fungi produce allergens known to be associated with allergies and asthma; many fungi also produce toxins and irritants with suspected effects on respiratory health.

Dampness may also promote bacterial growth and the survival of viruses, but this has received little attention in the literature.

In addition, dampness is an indicator of poor ventilation, which may result in increased levels of a wide range of other potentially harmful indoor pollutants.

Excess moisture may also result in increased chemical emissions from building materials and floor covers. Furthermore, standing water may attract cockroaches and rodents, which can transmit infectious diseases and are also a source of indoor allergens. These pests are not (just) specific to damp buildings.

Damp indoor environments (particularly damp soil and wood) may also attract termites, which can cause substantial damage to buildings, significantly compromising the integrity of the structure and therefore the health and safety of its occupants. Also, the presence of termites may indirectly affect the indoor environment by inducing the use (and misuse) of potentially hazardous pesticides. As termites are not known to affect indoor air quality directly, they are not discussed further in this document. Although outbreaks of legionellosis are commonly associated with water sources in buildings, they are not typically associated with damp buildings and are also not discussed further.