I don't think they're quite small enough to be pocketable, but some cities do sweeps with specialized on-car air quality equipment to find natural gas leaks (Bo

I don't think they're quite small enough to be pocketable, but some cities do sweeps with specialized on-car air quality equipment to find natural gas leaks (Boston leaks like a sieve, for example - https://www.edf.org/climate/methanemaps/city-snapshots/boston https://www.edf.org/climate/methanemaps/city-snapshots/bosto...)