Indonesia is battling its worst wildfires in more than a decade, made worse by El Niño. Many were deliberately set to clear land for farming, including palm oil plantations. More than 12,000 schools across Indonesia have closed because of the toxic haze. Natanael Undas, a school principal and photographer, has been documenting the fires on social media.

When actor Christina Applegate revealed that she had been misdiagnosed with multiple sclerosis, it triggered not only an outpouring of empathy for her, but raised important questions about how often people are told they have the condition when they don't. William Brangham discussed why MS can be so difficult to diagnose with Dr. Michael Kornberg of Johns Hopkins University.