In a lot of Asian cities, industry is relatively new. As such they’re not as prepared to deal with its less pleasant consequences as we are. Whereas we may have had the time or resources to lessen traffic or industry in city hubs, they won’t have. The health risks are less understood in the developing world and there’s simply less in the way of medical care to deal with them.
In the past smog has been known to damage lungs. This makes sense as you breathe in the smog where it can sit in your lungs and do damage for a long period of time. What was less known is the potential damage which can be done to your heart. In a lot of Asian cities high levels of smog with minute fine particles has led to a sharp rise in the number of people dying from heart attacks. Scientists are unsure exactly why it has this effect on the cardiovascular system and more study has been planned to work that one out. The fact that they’ve proven that smog does damage the heart is cause for concern on its own.