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 behavior of the community.
- They can cause shortages of food, with severe nutritional consequences.
- They can cause large population movements, whether spontaneous or organized, to areas where health services may be unable to meet increased demand.
Table 2. Frequent effects of disasters by type
Select each disaster type to review its frequent effects. For printing, expand all sections before printing.
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 centers 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 centers |
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 centers |
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 centers |
Severe but localized |
| 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 centers |
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 centers |
Severe but localized |
| Damage to water supply |
Severe but localized |
| 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 centers |
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.