Here in Los Angeles, we have some of the worst air quality in the country. But our air is only a fraction as polluted as New Dehli, India, which has some of the worst air in the world -- twice as bad as Beijing's. It’s a hazard for everyone living there, but especially children. Half of all schoolchildren have irreversible lung damage. That’s more than 2 million children. And that’s why Gardiner Harris, a correspondent for the New York Times, is leaving. He’s moving his family back to Washington after three years in Delhi, because he believes staying would risk his children’s long-term health. He recently wrote about the decision for the Times, and joins Madeleine to talk about it.