With the sky outside a menacing red, Nerilie Abram's family is staying indoors with the windows shut and curtains drawn at their home in Canberra, Australia's smoke-choked capital.

On their return from recent holiday travels, "the kids didn't want us to open the curtains because outside it looked scary," said the Australian National University climate scientist.

Family friends who struggle with asthma have left town, she said, and most residents who do venture outside wear disposable masks — though the city, which had the world's worst air quality for several days in the past week, is running out of those.