Winter is the time of year when cases of carbon monoxide poisoning rise, especially in colder climates. Homes are buttoned up tight as people try to stay warm. But, the invisible, odorless gas can strike in any season or any region and claims about 500 lives each year. Many more victims may suffer permanent injuries. A young motocross rider named Wyatt, who received care at Mayo Clinic in Rochester and Mayo Clinic Health System in Waseca, was one of the lucky ones. Here’s Dennis Douda for the Mayo Clinic News Network.