Smoke

http://www.spiegel.de/international/europe/0,1518,506730,00.html

"Health education campaigns costing millions of euros have nonetheless led to a decline in heart attacks over the last few years, at an annual rate of about 3 percent. But now it seems a miracle has happened: The number of heart attacks in Scotland has suddenly dropped by no less than 17 percent in a single year.

"What has happened? Have the Scots stopped eating red meat? Has the whole country started knocking back cholesterol medication? Are they all training for the marathon?

"No. The reason is much simpler: Scots are having fewer heart attacks because they are no longer inhaling other people's cigarette smoke when they sit in the pub, the train or the office."