public health adaptation strategies
  to extreme weather events

  • Heat waves
    Heat waves
  • Floods
  • Wildfires
  • Cold spells
    Cold spells
  • Synergies with air pollution
    Synergies with air pollution
  • Susceptible subgroups
    Susceptible subgroups

Extreme Weather Events

Results from PHASE show that EWEs have a significant impact on human health and are heterogeneous among population subgroups and between European cities.

Extreme temperatures
High temperatures and heat waves have a detrimental effect on human health. Heat effects are immediate or with a delay of 1-3 days and greater for respiratory and cardiovascular causes. In high economic developed countries the short-term mortality increase is due to the anticipation of deaths of very frail people, the so-called harvesting effect. Effects on mortality are greater than those on morbidity. Greater effects, with peaks in excess deaths have been reported during exceptional heat waves events such as the 2003 heat wave in Europe. Multicentre studies suggest stronger effects of extreme temperatures in the cities less acclimatized to heat. This factor is important when considering future climate change scenarios which predict an increase in mean temperatures and higher frequency of extreme events for Europe. It is important to consider that susceptibility factors vary over time and are heterogeneous in different settings based on local population characteristics (proportion of elderly, social-economic level, health care services, etc).
Cold weather may adversely affect human health, with both indoor temperatures and outdoor weather conditions having an impact on health. Mortality displays a seasonal pattern, with highest values during winter. The higher number of winter deaths depends on temperatures, the level of disease (especially influenza) in the population and other factors. Low temperatures have been associated with short-term increases in mortality in a linear way. Effects seem to be smaller and more prolonged (up to two or three weeks) than for heat and with the greatest impact on respiratory causes. In Europe deaths due to hyperothermia are a small proportion of winter deaths. Falls and injuries increase in winter due to snow, ice and heavy rainfall.
Few multi-city studies from Europe and the US are available and have documented a geographical variability in the impact of cold on mortality, with a greater effect in populations residing in warmer regions.
Inadequate indoor conditions in countries with milder winter climates, i.e. lack of adequate insulation or heating may explain the greater susceptibility of these populations. In winter, people spend more time indoors with less exchange of air and in overcrowded environments favouring the spreading of infections and the increase in respiratory infectious diseases. Cardiovascular diseases contribute substantially to cold-related mortality, particularly due to ischemic and cerebrovascular events that occur immediately or within a week of the onset of the cold weather.
Results from PHASE show a temporal variation in the effect of heat in 9 European cities, with a reduction in Mediterranean cities (potentially due to adaptation) and an increase in Scandinavian cities (higher exposure). Conversely for cold, there does not seem to be a clear temporal trend in the effect of cold and although effects are smaller compared to heat the burden of deaths in winter remains greater. Although less exposed, the effect of cold was higher in warmer cities which are unprepared to cope with cold weather. A case study conducted in Italy on the impact of the cold spell of 2012 showed a significant impact of cold in terms of excess deaths in several Italian cities. Greater efforts should be made to reduce mortality in winter and improve indoor micro-climatic conditions which may exacerbate the onset of cold-related health effects. Susceptible subgroups to heat/cold include: elderly, subjects with chronic disease associated to heat/cold, young children, pregnant women (risk of preterm delivery), people with low socio-economic status. Studies on preterm births conducted in PHASE denote a risk of preterm births in during heat waves in the last month of gestation with a potential heterogeneity in different cities by population characteristics and climate. Regarding young children, results from PHASE suggest an increase in total hospital admissions, respiratory and gastrointestinal admissions during days with high temperatures or during heat wave episodes. Heat and cold prevention plans need to include warning systems, rapid surveillance systems to monitor the effects of extreme events, the identification of susceptible subgroups and best practice prevention measures for these subgroups. Cohorts of susceptible subgroups to heat have been identified and need to be monitored to take into account the temporal variation in vulnerability factors.


Matteo Scortichini, Department of Epidemiology, Lazio Regional Health Service. Annual variations in the health effects of heat waves


Floods are the most common natural hazard in the European Region. In recent years member states have experienced some of the largest events in their history. The effects of flooding on health are extensive and significant, ranging from mortality and injuries resulting from trauma to infectious diseases and mental health impacts. While some of these outcomes are relatively easy to track, quantification of the human impact of floods in Europe remains challenging. The health effects of flooding can be divided into those associated with the immediate event and those arising afterwards. Immediate, direct effects are caused by the floodwater and the debris within it, but a flood continues to have health effects during the clean-up process and subsequently, which may persist for months or years. The longer-term, indirect health effects include those due to damage to infrastructure, food and water supplies, displacement and disruption to people’s lives and wellbeing. The health impacts and groups most vulnerable depend on the particular context\extent of the flood and responses to it. Vulnerable subgroups include elderly, children, people with chronic illnesses, people with physical\sensory\ cognitive impairments, residing in at risk floodplains or areas of hydrogeological instability or vulnerable housing. While some health outcomes are relatively easy to track, quantifying the human impact of floods in Europe remains challenging.


Within PHASE the development of contemporary surveillance indicators to monitor and assess the impact of flooding on health, and a health register protocol to improve preparedness and response to flooding. Furthermore, the creation and evaluation of public health guidance (before and after the winter 2013/14 flooding in England), has enabled the effectiveness of this intervention to be explored.

The successful completion of WP5 has significantly aided the development of the evidence base on the health impacts of flooding. The survey results of 27 member states has also enabled the development of a pan-European perspective. This added value to the project has helped ensure the outputs of WP5 are transferrable to other PHASE partners and member states. The three years of the PHASE programme has provided good learning at the EU level and demonstrated the impact of a common approach that utilises literature and science to inform policy. Furthermore, the use of case studies has raised awareness of different approaches and methodologies that can be applied to other hazards. The continued development of the evidence base using professionals’ good practice and research evaluation is essential.


Dr. Angie Bone, WP5 Leader, Extreme Events and Health Protection, Public Health England. Flooding, health effects and prevention measures. 



Wild fires

Wildfires take a heavy toll on human health worldwide, which is expected to increase since the main risk factors for wildfire - high temperatures, droughts and temporary dry spells - are exacerbated by climate change. Accidental health effects of wildfires are well-known. People involved in fires, firefighters but also local residents, face several life-threatening hazards including heat stress and fatigue as well as the risk of other injuries such as accidents, burns, cuts and scrapes. The literature review on health effects of wildfires has identified people suffering with

pre-existing cardiopulmonary conditions, elderly, smokers and, for professional reasons, firefighters as subgroups particularly vulnerable to smoke-related health risks in case of wildfires. These subjects experience more severe short-term and chronic symptoms. Various studies have established the relationship between one of the major components of wildfire, particulate matter [particles with diameter less than 10 µm (PM10) and less than 2.5 µm (PM2.5)] and cardiorespiratory symptoms in terms of Emergency Rooms visits and hospital admissions and more recently diminished birth weight in children of mothers exposed to wildfires. Within PHASE an inventory on the wildfires in Europe in terms of brunt surface, period of burning and wildfire emissions was constructed and will serve to evaluate the health impact of wildfires. The case study conducted in Marseilles, France showed an effect of fine particles (PM2.5) from wildfires on respiratory hospital admissions, suggesting a greater toxicity of wildfire smoke responsible for respiratory symptoms compared to anthropogenic PM2.5.


Air pollution

Air pollution is a well-known public health risk factor. In the past 25 years results from many epidemiologic studies gave evidence for a positive association between air pollutants concentrations and total and cause-specific mortality. Large multicity studies in Europe, USA and other part of the world, documented and quantified the adverse effects of air pollution on health. Fine particles (PM10, PM2.5), ozone, nitrogen dioxide and sulfur dioxide concentrations even at relatively low levels, have been linked with increases in morbidity and mortality.  Air pollution and has been reported among the 10 most important factors contributing to the Global Burden of Disease, globally as well as in Europe.  Meteorology and air pollution are associated. Climate change could affect air quality directly but also indirectly by affecting the proportional contribution of sources and via changes in human behavior.

Within the PHASE project, particular attention was addressed to the synergistic effects of extreme temperatures, air pollution and forest fires. Results from PHASE on nine European cities reported that high temperatures and high pollutant concentrations (ozone and PM10) interact and produce health effects that are more important than the sum of the two independent effects. In winter non-consistent interaction between temperature and air pollution was observed. Case studies carried out in Athens and Valencia showed evidence, although not consistent, on the synergy between the occurrence of forest fires and high particulate pollution levels effects on total, CVD and respiratory mortality. The relative toxicity of particles emitted by wildfires or originating from chemical processes associated with EWE is of importance for assessing the type and severity of health outcomes.

Climate change is expected to lead to an increasing frequency of EWE and forest fires, leading to even larger effects of air pollution on health, if synergy is a reality.



Prof. Klea Katsouyanni, WP7 leader - Department of Hygiene, Epidemiology and Medical Statistics, National and Kapodistrian University of Athens, Greece. Interactive effects of extreme weather events, forest fires and air pollution on health. 


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