Issue link: https://hi.iaq.net/i/191637
Climate Change, the Indoor Environment, and Health 164 CLIMATE CHANGE, THE INDOOR ENVIRONMENT, AND HEALTH (Voorhorst et al., 1969). Dermatophagoides pteronyssinus (de Boer and Kuller, 1997; van Strien et al., 1994; Voorhorst et al., 1969) and D. farinae (Antens et al., 2006) are commonly recovered in home settings. D. farinae is the hardier of the two (Arlian, 1975; Arlian and Veselica, 1981). An intervention study showed that the major allergen from D. pteronyssinus may have been decreased by an extremely dry (and cold) winter during the study period rather than by the home interventions themselves (Brunekreef et al., 2005; Gehring et al., 2005). Dust mite viability is highly influenced by environmental conditions. There may be some inferences that as the climate warms, dust mites will thrive (Ayres et al., 2009). That is not entirely true. As noted in Chapter 2, although some regions of the country will experience warmer climates, they will not necessarily experience higher humidity. The critical factor for dust mites is water activity (Aw), which is relative humidity at a surface. Dust mites do not have lungs that can condition the air; rather, they conduct transpiration through their exoskeletons. A decrease in ambient relative humidity (which is paralleled by a drop in Aw) can affect dust mites not only in laboratory settings (Arlian, 1975; Arlian and Veselica, 1981) but in the home (Arlian et al., 2001; Cabrera et al., 1995; Harving et al., 1994) and at a community level (Acosta et al., 2008; Chew et al., 1999). New York and Boston are coastal cities, but many of their homes can be dry in winter, and this factor eradicates the dust mite population. Studies indicate that increased indoor temperature in those communities has not been accompanied by an observed increase in the dust mite population; rather, dust mites decreased (Acosta et al., 2008; Chew et al., 1999). The homes where overheating was measured in these studies were multifamily apartment buildings whose residents had little control over their heating. The heating was turned on (building wide) early in fall and turned off late in spring. Figures 6-1 and 6-2 illustrate how overheated apartments compared with single-family homes whose residents had more control over their heating. A change in climate could also affect the ecologic niches of some types of dust mites in such a way that the geographic patterns of endemic dust mites could change. As discussed earlier, some dust mites are more sensitive to humidity than others. The Dutch intervention study described earlier (Brunekreef et al., 2005) showed not only that dust mite levels decreased in this coastal country but that the profile of dust mite taxa had changed. Although it was not highlighted in the study, careful examination of one of the figures shows that between the beginning of the study (1996) and eight years later, Der f 1 (the major allergen from D. farinae) apparently became the most highly concentrated allergen in house dust (Antens et al., 2006). Even if humidity does not change substantially, warmer climate patterns are predicted, and this (in the absence of any adaptation measures, such as Copyright © National Academy of Sciences. All rights reserved.