If you're wonder why I looked even less photogenic than normal in some of those trip photos...

In 2004,Cairo was ranked #1 on the World Bank's List of the Planet's Most Polluted Cities.

Since then the situation has improved a bit, but here's the intro to a story from Voice of America last month:

The World Health Organization says just breathing the air in Cairo, Egypt, for one day is equivalent to smoking 20 cigarettes.