We haven't, not that much.
What you mention is very interesting. If we compare the rates of SO2 and NO2 and fine particles in Montreal—I know this region quite well—we see that from the seventies up to now, there's been a dramatic drop of SO2 and NO2. What were we breathing in the seventies? It's incredible. Now it's better.
However, we have an average of about 15 micrograms of fine particles per cubic metre. The average is 15 micrograms, which is not that good. If you look at downtown Montreal, only one day out of three is considered “good”. Two-thirds of the days are “good enough”, and 60 a year are “bad”.
Very recently, a study from Boston's Harvard University said that when you go from a “good” day in terms of pollution to a “good enough” day, which is an average, you increase the rate of strokes in the city of Boston by 25% to 40%. Boston and Montreal have a lot of similarities there.
So it's not good enough. We should continue with those studies, because it's a way to have better health globally.
I love to implant stents, to save lives, to put in valves. It's fun, but honestly I would say to the people around me, “Don't need me.” I wasn't at all aware of the environment as a measurable part five years ago, I can tell you, but now the science is there, and we can have this conviction. It's the same as for physical activity and smoking: the environment is as important as that.