Question

Why might establishing a direct link between air pollution and health problems be difficult?

Answer 1

Other confounding factors that also influence human health.

Explanation:

Air pollution is but one factor that has an impact on overall human health - in particular, respiratory health (lungs).

For example, a person with a lung disease any number of factors may be at play: genetic predisposition to asthma, childhood exposure to allergens, overuse of antibiotics early in life, exposure to tobacco smoke (primary or second-hand) and/or exposure to air pollution (which can include indoor or outdoor air pollution). In many developing countries, like India, indoor air pollution form smoky cooking fires can be a major health problem, especially for women and children who spend a lot of time indoors.

So, teasing apart all of these factors and there direct impact on a disorder can be a very difficult experimental task.

Researchers some times used identical twins for such studies - especially twins who grew up in separate environments.