Indoor air quality is impacted by the infiltration of pollutants from outdoor air as
well as from indoor emission sources. Increases in outdoor temperatures and longer
periods of home air conditioner (AC) usage, with the house closed and air-sealed to
minimize leakage (i.e., recirculation air conditioning with no mechanical outdoor air
ventilation), result in longer periods of reduced air exchange rates. However, even
during these periods of reduced air exchange, the quality of indoor air is impacted by
the quality of outdoor air, but to a lesser extent than the examples provided above when
the air exchange rates were higher.
INCREASED TEMPERATURE
Hyperthermia is already the leading cause of weather related death in the United
States (MMWR 2006). As temperatures in some areas of the country increase,
hyperthermia related deaths will also increase particularly in individuals of low
socioeconomic status who lack finances to cool their homes. The elderly, young
children, pregnant women, and individuals with chronic medical conditions will also be
at higher risk. In addition to hyperthermia, increasing indoor air temperatures typically
increases the emissions rates of volatile organic compounds (VOCs) from building
materials, furnishings, carpeting, personal care products, cleaning and deodorizing
products, etc. as well as the interactions between indoor pollutants.
INCREASED HUMIDITY
Willett et al. (2007) have identified a significant global-scale increase in surface
specific humidity, which they attribute primarily to human influence. The researchers
noted that the specific humidity has increased in response to rising temperatures and
that these changes may be predictive of increased intensity of precipitation. Increased
precipitation, leading to moldy interiors of homes as well as increased humidity indoors,
has the potential to significantly increase airborne exposure to fungi, including
mycotoxin-producing fungi, and the microbial volatile organic compounds (MVOCs) they
produce. In addition, increased dampness can increase the release of chemicals and
particles from building materials; and increase the amount of bacteria, dust mites,
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