Make sure you have the appropriate smoke detectors and carbon monoxide detectors.  

Almost pure carbon, burns real clean.

Hopefully it is nothing caused by the building (carbon monoxide poisoning, etc.).I agree with others above, let them out of the lease. 

Make sure everything is safe and up to code (electrical, smoke and carbon dioxide detectors, etc.).

My bank has little carbon copy receipts in the lobby.  

You could also reach out to Kevin Carbon.

And all this time, I thought it was the 'intellectually void' that put the current carbon based being in the White House.

Hamilton Twp ZHB set forth the current surge in municipal regulation of short-term rentals.Below is a list of municipalities in Carbon County and neighboring areas with an estimate as to their current position regarding the use of vacation rentals from individual homes.

I could still do carbon straps on my walls for $8K, just incase they want to bow in the future....but...from everything I can see....this would be the best and cheapest solution.

@John Carbone I agree about the instant booking and the value of the immediate replies to instant bookings, letting the guests know the house rules and enforcement policy and giving them 48 hours to cancel.