Severe storms and flooding frequently lead to electrical power outages and dislocation from homes, which can adversely affect indoor pollutant exposures.
In most buildings, losses in electrical power deactivate heating and cooling systems. The resulting high or low indoor air temperatures impose thermal discomfort and thermal stress, and can affect health. The effects of high temperatures are discussed in the section on heat stress. There is evidence that cold indoor temperatures have adverse consequences for health; although, the data are not specific to short periods of cold indoor temperatures from short-term losses in electrical service following severe storms. Cold temperatures have been associated with increased cardiovascular and respiratory mortality [30, 31]. Analyses of data from Europe show that the increase in mortality during cold weather is higher in regions with more prevalent absence of thermal insulation of building envelopes, more single pane windows, and more fuel poverty , indicating that low indoor temperatures increase mortality risks. A study of adding thermal insulation to homes serving a low income population in New Zealand also provides evidence of improvements in temperatures, comfort and several health or health-related outcomes (self-reported colds and flu, wheeze, sleep disturbed by wheeze, visits to a general practitioner, and days of missed work and school) [32, 33]. However, there was a large reported decrease in mold in the homes after addition of insulation; thus, it is not certain that the improvements in health are a consequence of the increases in indoor air temperature, which were modest, averaging 0.5 °C (1 °F). Also, relative to temperatures in U.S. homes, indoor temperatures in the New Zealand study population were low, averaging less than 14 °C (57 °F) in the bedroom. Thus, the available data suggest, but do not confirm, adverse health consequences from periods of low indoor temperatures resulting from losses of power after severe storms.
During power outages caused by severe storms, the use of backup generators increases and these generators are a source of carbon monoxide. There is evidence that hospital visits for carbon monoxide poisoning increase during major storms and floods . Analysis by the U.S. Consumer Product Safety Commission for the 1999 - 2012 period indicates that 91% of the carbon monoxide deaths associated with power outages are attributable to weather conditions, with hurricanes associated with 29% of these deaths . Consequently, cases of indoor carbon monoxide poisoning may increase as a result of the expected increase in severe storms and floods with climate change.
Severe storms and floods lead to dislocations of families from their homes to temporary housing and emergency shelters where exposures to contaminants are sometimes increased. Hurricanes Katrina and Rita led to the use of temporary housing units for over 120,000 displaced families in the United States . The average formaldehyde concentration in a sample of 519 trailers used for temporary housing was 77 parts per billion (ppb) and the maximum concentration was 590 ppb. These concentrations are substantially higher than the average and peak values of 35 and 110 ppb in a survey of new California homes . Formaldehyde is an irritant, has been declared a human carcinogen by the World Health Organization, and may affect allergies and asthma, as discussed in the section of this web site on Volatile Organic Compounds and Health.
Various buildings, including schools, churches, and assembly buildings are used as emergency shelters for people after their homes are flooded or damaged by severe storms. The Superdome sports facility in New Orleans has been used three times as an emergency shelter. Up to 20,000 people lived briefly in the Superdome after Hurricane Katrina. Because these buildings were not designed to serve as housing and may be crowded when used as emergency shelters, ventilation and indoor air quality conditions may be poor and risks of transmission of infectious diseases may increase. However, there is no significant body of literature with which to assess these concerns.