What is the relationship between environmental variables and the incidence of disease? How is this changing?

There are many conditions that demonstrate that the environment has a large impact on health. For example, cholera from polluted water supplies, increased cataracts from the sun, asthma from air pollution. Therefore, whether there are more or less of these environmental variables there is more or less of that type of disease and the WHO (World Health Organisation) recognises that there is a clear link between these factors. With climate change and urbanisation the incidence of these environmental variables and therefore the incidence of disease is changing. For example, urbanisation and development has caused increases in pollution and therefore related diseases (such as Cholera) are increasing. The incidence of vector bourne diseases such as malaria is changing due to global warming as the latitudes and altitudes where the mosquitoes can survive is being affected.