They can only spend about 20 or 30 minutes before they run into pockets of carbon monoxide. It takes such a toll they have to come out and rest for about an hour.  -   Joe Allbaugh     Quotes
They can only spend about 20 or 30 minutes before they run into pockets of carbon monoxide. It takes such a toll they have to come out and rest for about an hour. Joe Allbaugh