I read this claim attributed to a landlord in Balclutha, New Zealand:
"It's very hard to tell if a house is infected because you can't really see it. There are telltale signs for landlords, like light bulbs missing all the time. But you can't smell it or see it.''
I have a rental at the other end of the country, in Auckland, where P use is much more prevalent. One family (academics, two small kids) seemed to be getting through lightbulbs far faster than usual. Are there grounds for concern?