Why might it be difficult to establish a direct link between air pollution and health problems?
It is difficult to draw a cause-effect relationship in a specific instance of a disease state.
That was kind of convoluted lets discuss this a bit more.
So, lets say a single child living in Pollution-ville (population 30,000) was just recently diagnosed with asthma. Pollution-ville has numerous factories, most of these factories release sulfur dioxide (
This is where epidemiology comes into play. Epidemiology is the study of patterns, causes, and effects of health and disease in a population.
Lets say that this child's asthma diagnosis is the 60th newly diagnosed case of pediatric asthma in the past month. All of the newly diagnosed children live in Pollution-ville. This large number of new diagnoses point toward a common environmental factor rather than a random event.
Lets continue in our case against
The epidemiologist would then look at other cities (besides Pollution-ville and Bad Aire) with factories that release
In the most general case we would need to find a general trend which would need to be tested in a lab to prove that the particular agent is linked to a disease state. We should also keep in mind that most factories and other sources of air pollution release more than 1 chemical into the air and any one of these chemicals could be our disease causing agent.
This makes it can be incredibly difficult to establish that a particular pollutant is responsible for a particular disease state.