> how many more people die of heart disease when pollution is present Exactly. And I'm saying that question is much more difficult to answer than some people p

> how many more people die of heart disease when pollution is present Exactly. And I'm saying that question is much more difficult to answer than some people probably think. Heart disease is so extremely prevalent, and there are so many variables at play that I find it hard to believe anyone can confidently answer that question definitively, at least so far as to claim that pollution is "responsible for" the deaths of X number of people. It's especially hard to isolate because the dependent variable (pollution) and the independent variable (number of heart disease-related deaths) have both been increasing, and pollution levels are positively correlated with a lot of other risk factors for heart disease.