My parents' neighbor's home was billowing black smoke and a good samaritan ran in to rescue them. Turns out they were fine. Everyone was relieved. Then the neighbor told them that this always happens when he uses carpet samples in his fireplace. The EPA was called in. They took an air sample. The neighbor had been hitting up carpet shops and gathering samples thinking they'd be great to start a fire. And while the price was right, most humans would agree that it's unwise to burn carpet in your fireplace. All the chemicals and adhesive can't be good for you. Reminds me of the s'mores my friends used to toast over treated lumber.