Estimating Number of Elderly Affected by Atlantic Storms in 1998-2002 using Geographical Information System

Natural disasters pose a serious threat to welfare of vulnerable populations. Due to infrastructure disruption and population displacement that typically occur as the consequences of extreme weather events, the assessment of health effects is difficult. Often even simple estimates of affected population are not readily available to public health professionals. In this study, we develop methodology for estimating the number of elderly affected by Atlantic storms in 1998-2002 using Geographical Information System (GIS).

Information on 25 storms was abstracted from the U.S. National Oceanic & Atmospheric Administration including date, time, and epicenter coordinates in a six-hour interval. To reflect degree of exposure the storm tracks were mapped with three buffers: 50, 75, and 100 miles from storm trajectory. Number of elderly older than 65 affected by storms were estimated by overlaying the storm buffer areas with county maps linked to Census 2000 demographic data. Counties with centroid inside in the buffer area were considered affected.

Of 25 Atlantic storms made landfall between 1998 and 2002, 5 were category 4 or higher, 6 were category 2 and 3. In the 31 states from South Atlantic, Middle Atlantic, New England, East North Central, and West South Central divisions, the recorded storms have accumulatively affected 3,531 counties with 390.3 million people out of whom 49.7 million (12.7%) were elderly. Proportion of elderly affected to total population varies storm by storm, from 0.2% to 33.4%.

The obtained estimates provide important insights on the magnitude of exposure to extreme weather events among the US elderly.