It’s 3:50 a.m. and I’m awake, looking at pictures of sweet potatoes on Instagram. I like to sleep with the big window above my bed open so fresh air circulates all night, but lately that’s impossible as noxious smoke and wildfires consume California. The smell wakes me many nights, and there’s no point trying to go back to sleep before my overworked air purifier has had a full hour to pull the worst of it out of my bedroom. Until