Section 2: The Health Impact of Disasters

Disasters often have a significant impact on public health. In more vulnerable parts of the world, that impact can be exacerbated by weak or nonexistent health care systems and infrastructure. In this section, we will explore some of the most common health issues associated with international disasters.

Illustration of a globe.

Common Disaster Health Issues

Following are some of the most common health impacts of disasters. Select each issue to learn more about it.

Health Impacts of Selected Types of Natural Hazards

All major disasters potentially present an increased risk of communicable diseases due to overcrowding and deteriorating sanitation. Table 1 summarizes several additional health impacts of selected disaster types.

Disaster Type Deaths Severe injuries requiring extensive treatment Damage to health facilities Damage to water systems Food shortage Major population movements
Earthquakes Many Many Severe, structure and equipment Severe Rare (may occur due to economic and logistic factors) Rare (may occur in heavily damaged urban areas)
High winds, without flooding Few Moderate Severe Light Rare (may occur due to economic and logistic factors) Rare (may occur in heavily damaged urban areas)
Tidal waves / flash floods Many Few Severe, but localized Severe Common Common, generally limited
Slow-onset floods Few Few Severe, equipment only Light Common Common, generally limited
Landslides Many Few Severe, but localized Severe, but localized Rare Common, generally limited
Volcanoes / Lahars Many Few Severe, structure and equipment Severe Rare Common, generally limited

Table 1 - Health Impact of Selected Major Disasters

Notice, for example, that earthquakes cause many deaths, while slow-onset floods generally cause few. Floods produce serious food shortages, whereas earthquakes, which are localized, generally do not.

Climate Change: A Growing Driver of Disaster Risk

Note that the information in Table 1 does not even consider the impact of climate change on health. The World Health Organization now considers climate change one of the top ten threats to global health.

The Inter-Governmental Panel on Climate Change (IPCC) is the leading international body for the assessment of climate change. It was established in 1988 to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts.

Screenshot of the IPCC website, stating 'The Intergovernmental Panel on Climate Change (IPCC) is the United Nations body for assessing the science related to climate change.'


The IPCC is a scientific body under the auspices of the United Nations (U.N.). It reviews and assesses the most recent scientific, technical, and socio-economic climate change information produced worldwide. It does not conduct any research or monitor climate-related data or parameters.

Check back frequently with the website to view the outcomes of various Conference of the Parties (COP) to the United Nations Framework Convention on Climate Change (UNFCCC) and related events.

View the latest assessment reports on climate change.

Yale University's Program on Climate Change Communication conducts research on public climate knowledge, risk perceptions, decision making, and behavior so that educators and communicators have the knowledge and tools to more effectively engage their audiences. 

Distinguishing Between Weather and Climate

The difference between weather and climate is a measure of time. Weather is the set of meteorological conditions at a particular time and place—wind, rain, snow, sunshine, temperature, and so on. By contrast, the term climate describes the overall long-term characteristics of the weather experienced at a particular location.

Learn More

Dark storm clouds over a green field, with possible tornadic activity brewing.

Image Source: NOAA

How Climate Change is Affecting Health

The projected changes in climate are likely to alter the health status of millions of people. Heat waves, floods, storms, fires, and droughts will increase the number of deaths, cases of disease, and injuries. Increased malnutrition, diarrheal disease, and malaria in some areas will jeopardize public health. Development goals will be threatened by longer-term damage to health systems from disasters.

The World Health Organization states:

  • Climate change affects the social and environmental determinants of health—clean air, safe drinking water, sufficient food, and secure shelter.
  • Between 2030 and 2050, climate change is expected to cause approximately 250,000 additional deaths per year, from malnutrition, malaria, diarrhea, and heat stress.
  • The direct damage costs to health (excluding costs in health-determining sectors such as agriculture, water, and sanitation) is estimated to be between U.S. $2 to 4 billion per year by 2030.
  • Areas with weak health infrastructures—mostly in developing countries—will be the least able to cope without assistance to prepare and respond.
  • Reducing emissions of greenhouse gases through better transport, food, and energy use choices can result in improved health, particularly through reduced air pollution.


Compact of Mayors

The Compact of Mayors was launched at the 2014 U.N. Climate Summit and is the world's largest coalition of city leaders addressing climate change. The agreement set targets around greenhouse gas emissions reduction and urban resilience. It also established a reasonable time frame to conduct and disclose a greenhouse gas inventory and climate vulnerability assessment. The purpose is to make clear to the community of nations just how much cities and local communities are leading in the area of climate change. The same rigor and disclosures are expected from countries around the world.

Screenshot of the C40 Cities website, on the Compact of Mayors page. The Compact of Mayors is the world's largest cooperative effort among mayors and city officials to reduce greenhouse gas emissions and climate risks in cities.

Activity: Application

We have now described some of the most commonly occurring health problems in disaster situations. We provided links to reference documents that provide more in-depth information on these issues. Complete the following exercise to determine how you can use this information in your work. If desired, download the Application Activity Microsoft Word document document to note your thoughts and responses.

  1. Take some time to reflect on disasters or emergencies that you have experienced or read about.  You can use the example of a local emergency in your state or region, or a major U.S. disaster such as Hurricane Katrina or Superstorm Sandy.
  2. Were there problems related to water? Infectious diseases? Mental health? Damage to hospitals? Evacuation and/or displacement? Describe these.
  3. What other problems or issues have you encountered in the aftermath of an emergency or disaster that were not mentioned previously? How were they managed? Do you think these issues are unique to the U.S. or do they occur in other countries?

Key Points

In this section, we covered the following main points:

  • Some of the most common disaster health issues include water and sanitation, communicable diseases, dysfunctional health facilities, mental health problems, and population displacement.
  • Climate change is a growing threat to global health as it impacts the social and environmental determinants of health, including clean air, safe drinking water, sufficient food, and secure shelter.