Researchers have identified a strong link between outdoor air pollution and heart attacks. A study in England estimates that 1 in 50 coronaries treated in London hospitals may be triggered by air pollutants such as nitrogen dioxide, sulfur dioxide, carbon monoxide, and black smoke. Many of these deaths might be avoided with better control of pollutants, particularly motor vehicle exhaust emissions. Carbon monoxide emissions are a particular cause of concern because the pollutant can reduce the blood's ability to transport oxygen around the body -- a factor that can seriously affect heart tissue already compromised by ischemia, or decreased blood flow. This is probably the main reason why smoker's have an increased risk of heart attacks.
Occupational and Environmental Medicine (1997;54:535-540)