Carbon monoxide is odorless, tasteless, colorless, and slightly less dense than air. Also it will poison and then kill you. Part of what makes Carbon monoxide so deadly is because it's difficult to detect; it's sometimes called the "silent killer." It inhibits your body's ability to carry oxygen where it's needed - like to cells. To keep them alive and stuff. Early carbon monoxide poisoning symptoms are similar to the flu, minus the fever - headaches, weakness/lethargy, sleeplessness, nausea, & confusion. Luckily, you can get a carbon monoxide detector at every hardware or home improvement store!