3. Definitions

3.3. Effects of disasters

Disasters affect communities in multiple ways. They represent a public health hazard for various reasons (Table 2):

  • They can cause an unexpected number of deaths and injured or sick people that exceed local response capacity and require external aid.
  • They can destroy health infrastructure, affecting the immediate response and disrupting preventive activities, which may lead to long-term increases in morbidity and mortality.
  • They can have adverse effects on the environment, increasing the risk of infectious diseases and environmental hazards. This can affect morbidity, premature death, and future quality of life.
  • They can affect the psychological and social behaviour of the community.
  • They can cause shortages of food, with severe nutritional consequences.
  • They can cause large population movements, whether spontaneous or organised, to areas where health services may be unable to meet increased demand.

Table 2. Frequent effects of disasters by type

Complex emergency
Immediate deaths Numerous
Severe lesions Numerous
Increased risk for transmissible diseases This risk applies to all significant disasters and increases with overcrowding and deterioration of sanitary conditions.
Damage to health centres Moderate; can be severe if health centres are military targets
Damage to water supply Severe
Food shortage Severe
Significant population displacements Frequent
Earthquake
Immediate deaths Numerous
Severe lesions Numerous
Increased risk for transmissible diseases This risk applies to all significant disasters and increases with overcrowding and deterioration of sanitary conditions.
Damage to health centres Severe
Damage to water supply Severe
Food shortage May result from economic and logistic factors
Significant population displacements Frequent; increased likelihood in severely damaged urban areas
Strong winds
Immediate deaths Few
Severe lesions Moderate
Increased risk for transmissible diseases This risk applies to all significant disasters and increases with overcrowding and deterioration of sanitary conditions.
Damage to health centres Severe
Damage to water supply Slight
Food shortage May result from economic and logistic factors
Significant population displacements Not frequent
Floods
Immediate deaths Numerous
Severe lesions Few
Increased risk for transmissible diseases This risk applies to all significant disasters and increases with overcrowding and deterioration of sanitary conditions.
Damage to health centres Severe but localised
Damage to water supply Severe
Food shortage Frequent
Significant population displacements Frequent
Gradual floods
Immediate deaths Few
Severe lesions Few
Increased risk for transmissible diseases This risk applies to all significant disasters and increases with overcrowding and deterioration of sanitary conditions.
Damage to health centres Severe (equipment only)
Damage to water supply Slight
Food shortage Frequent
Significant population displacements Frequent
Mudslides
Immediate deaths Numerous
Severe lesions Few
Increased risk for transmissible diseases This risk applies to all significant disasters and increases with overcrowding and deterioration of sanitary conditions.
Damage to health centres Severe but localised
Damage to water supply Severe but localised
Food shortage Not frequent
Significant population displacements Frequent
Volcanic eruptions
Immediate deaths Numerous
Severe lesions Few
Increased risk for transmissible diseases This risk applies to all significant disasters and increases with overcrowding and deterioration of sanitary conditions.
Damage to health centres Severe
Damage to water supply Severe
Food shortage Not frequent
Significant population displacements Frequent

Adapted from Humanitarian Assistance in Disaster Situations. A Guide for Effective Aid. Pan-American Health Organization (PAHO). Washington D.C., 1999.