Human behaviour is the overwhelming cause of increasing vulnerability to natural hazards. This global development is directly linked to a number of trends, such as increasing poverty, population growth and greater density, unwise land use and inadequately planned urbanization, environmental degradation and disturbance of formerly stable ecosystems, and climate change. Combinations of factors make specific areas even more susceptible. For instance, the population boom in urban and coastal areas has compounded factors such as high population concentration, vulnerable infrastructure, and settlements built in floodplains or areas prone to landslides. Misguided planning has also increased the vulnerability to disasters by siting potentially-hazardous facilities - such as nuclear power plants, chemical factories and major dams - in earthquake zones and densely-populated areas.
Human health consequences of changes to the natural environment arise particularly from induced climate and atmospheric-related stress. Ozone layer thinning, increasing the UV flux at the earth's surface, is already producing increased incidence of (a) infections and epidemics due to immunosuppressive impacts; (b) sunburn and premature aging of the skin due to direct dermatological effects; (c) melanocytic (malignant) and squamous and basal cell neoplasias (skin cancers); and (d) cataracts.
Climate change due to global warming is predicted to influence the incidence of (a) heat stress illnesses, affecting particularly urban areas and vulnerable groups (the very young, old, and those with cardiovascular or respiratory disease); (b) heat induced violence; (c) respiratory and allergenic diseases through changes in grass seeds and pollen counts; (d) vector-borne diseases due to ecosystem changes affecting insects; (e) weather emergencies and natural disasters, such as floods and droughts; (f) water-borne diseases, such as faecal-oral infections due to precipitation changes; and (g) famine and undernutrition which will increase migration and the diseases of migrants.
Children are in a dynamic state of growth and more susceptible to environmental threats than adults.