Santa Shouldn't Smoke

So I was reading Twas The Night Before Christmas to Lincoln tonight before bed, and we got to the part:

The stump of a pipe he held tight in his teeth,
And the smoke it encircled his head like a wreath.

Lincoln cut in and said, "Did Santa breathe in the smoke?"

"Yes," I said.

"That's not very good for Santa," Lincoln replied in a solemn voice. It prompted a small chuckle, but he was dead serious.