Table 4 Key Statements in the WAO White Book on Allergy, Update 2013, World Allergy Organization 2014, page 16. Reprinted with permission from the editors [159]

The earth’s temperature is increasing as illustrated by rising sea levels, glaciers melting, warming of the oceans and diminished snow cover in the northern hemisphere.

Climate change coupled with air pollutant exposures may have potentially serious adverse consequences especially for human health in urban and polluted regions.

High summer temperatures have an impact on rates of acute exacerbation and hospital admission for elderly patients with breathing problems and may cause unexpected death.

Pollen allergy is frequently used to study the interrelationship between air pollution and respiratory allergy. Climatic factors (temperature, wind speed, humidity, thunderstorms, etc.) can affect both biological and chemical components of this interaction.

Changes in the weather such as thunderstorms during pollen seasons may induce hydration of pollen grains and their fragmentation which generates atmospheric biological aerosols carrying allergens (see also sections on thunderstorms and sandstorms in this document). As a consequence asthma outbreaks can be observed in pollinosis patients.

Migration from one country to another involves exposure to a new set of pollutants and allergens as well as changes in housing conditions, diet and accessibility to medical services which may affect migrants’ health.

Atopy and asthma are more prevalent in developed and industrialized countries compared with undeveloped and less affluent countries.

Migration studies provide information on the role of environmental factors on the development of atopy and asthma.

Physicians should be aware that environmental and climate changes may enhance the development of allergic diseases and asthma.

Physicians should be aware that migrants, especially from developing to more developed countries, are at increased risk to acquire allergic diseases and asthma and that the effect is age and time-dependent. Earlier age and longer time increase the likelihood of developing atopy and asthma.