Impact of Weather on Health
Center of Disease Control
The adverse impact (mortality and morbidity) of certain types of weather events on health is
significant, and considerable effort is directed at reducing this impact. In these efforts, it is
important to have a good understanding of the number of people affected by each weather event
and the ways in which each event produces its adverse effects. Such understanding is crucial to
the implementation of measures to prevent adverse effects from similar weather events in the
Table 1 shows deaths from weather events and earth movements in the U.S. 1979-94.
Lack of Common Definitions
To determine the number of people affected by a weather event, one must decide which deaths,
injuries, and illnesses should be counted and be aware of good sources of information on health
affects. At present, there is no generally accepted definition of what constitutes a weather-related
death, injury, or illness. Furthermore, those attempting to assess the impact of weather events
may use different sources of information. As a result, it may be difficult to compare the impacts
of different weather events on mortality and morbidity, and different groups may report
dissimilar numbers of persons affected by the same weather event.
Each of the following scenarios presents a death that occurred at the time of or shortly after a
weather event. Even among medical examiners, who are usually responsible for investigating
and determining the cause of deaths due to injuries and violence and who were asked to review
these scenarios at a recent meeting, there is often disagreement on what constitutes a
"disaster-related" death. Mortality data from several eastern U.S. cities affected by the 1993 heat
wave reinforce this point.
Relationship of death to disaster in seven scenarios, as judged by medical examiners
at the annual meeting of the National Association of Medical Examiners, Charleston, South
- Roof trusses from a neighbor's home were blown off during a hurricane, penetrating the roof
of the decedent's home, striking her in the head. She died from blunt head injury.
- During a hurricane, a 72 year old man with a history of heart disease was in his garage
lifting a piece of plywood to repair a storm-damaged window, when he collapsed and died
immediately. Cause of death was cardiac dysrhythmia.
- Two days after a flood, a family was still without power. Because the decedent was afraid of
the dark, her mother left a candle burning in her bedroom. During the night, the candle fell over
and started a fire. The decedent died from carbon monoxide poisoning.
- 15 days after a tornado occurred, a workman was asphyxiated when a storm-felled tree trunk
toppled back over, trapping him beneath its roots.
- The decedent - armed and apparently intent on looting a storm-damaged home - approached,
shot at, but missed a homeowner; but the homeowner, defending his property, and himself, shot
the would-be robber in the head.
- A husband shot and killed his wife and then himself 6 months after a hurricane; they were
still living in temporary housing and their marriage had become unstable.
- The decedent was from another state. He was in the area providing relief efforts to victims
who were displaced by a flood when he was stung by a hornet and died from anaphylactic shock.
The decedent had no known history of allergies or previous exposure to stinging
Death related to disaster? If yes, directly or indirectly?
To determine whether a death, injury, or illness is related to a weather event, the health effect
must be temporally and geographically related to the weather event, and make causal and
biological sense. Thus, in counting people affected by weather, one must establish reasonable
geographic and time frames, and assess the nature of the circumstances and health effects:
- Time Frame - One should establish an explicit starting and ending date for counting
health effects. For example, for a weather event such as a hurricane in which preparations,
including evacuation, can be made and for which physical destruction of the natural and built
environment is extensive and, therefore, clean-up after the event is often prolonged, the time
period could extend from one or more days prior to the event to two or more months after the
event. For an event with little or no advanced warning and little clean-up, for example, a severe
hail storm, the time frame may start with the event and end the same day.
- Geographic Frame - One should establish the geographic area in which people may
be affected by the weather event. For example, an affected person must have been present in the
county or counties affected by a tornado to be counted.
- Circumstances - A death, injury, or illness is directly related to a weather event if it
is caused by the direct environmental effect(s) of the weather. A death, injury, or illness
is indirectly related to a weather event if it is caused by unsafe or unhealthy conditions
that occurred because of the anticipation or occurrence of the weather event. These conditions
include the loss or disruption of usual services, personal loss, and disruption of an individual's
lifestyle. We divide these indirect effects into those caused by (1) unsafe or unhealthy
conditions that caused a loss or disruption of usual services (including medical care services) or
(2) temporary or permanent displacement, property damage, or other personal loss or stress.
- Biological Sense - For a death, injury, or illness to be related to a weather event, the
circumstances leading to the health effect and the reported health effect must make causal and
biological sense. For example, a lung cancer which results in someone's death two days after a
hurricane could not be causally related to the weather event. It is possible, however, that the
death of someone whose medical care for lung cancer was disrupted by the hurricane could be
attributed to the hurricane.
Source of Information
The Public Health Consequences of Disasters, edited by Eric K. Noji, Oxford University Press,
New York, 1997.
Societal Aspects of Weather
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