Indoor Damp and Asthma Exacerbation: A Causal Relationship in Young Children


A recent review by the Institute of Medicine on the impact the indoor environment has on asthma has upgraded some of its conclusions. The updates reflect a firming up of scientific evidence.

The report grades evidence according to three categories of relationship:

    • A causal relationship is one where the authors consider the available evidence is strong enough to suggest that we have found something that causes the health outcome – this is the strongest relationship and strongly suggests that an intervention is needed.

    • If they do not yet consider that there is enough evidence to suggest a causal relationship then they can opt for an association between environmental factor and health impact.

    • Finally if evidence is found that there is no relationship between an environmental factor and a health outcome then the conclusion is that there is evidence of no association.

    Major changes since 2000

    1. There is now a causal relationship with exacerbation for indoor dampness or dampness-related agents (in children)

    2. There are now associations with exacerbation for dampness or dampness-related agents (in adults), endotoxin, and environmental tobacco smoke (in preschool children)

    3. There is limited or suggestive evidence for association with exacerbation for indoor culturable Penicillium or total fungi, nitrogen dioxide, rodents (non-occupational), feather/down pillows (protective relative to synthetic bedding), and (regardless of specific sensitization) dust mite, cockroach, dog, and dampness-related agents.

It is clear that those with asthma should avoid living in damp homes, especially if they have children.