Old Biscuit - you're right. Smoke is particles, CO2 is gas with no smell or color. They usually come together, when something is burning.
CO2 is not poisonous, but it will eventually kill us all because it affects the climate. This is what is called a "greenhouse gas". Safe concentration is 350 ppm, but due to human activity it rose above this level 25-30 years ago (I think it's well above 400 now), and keeps on rising - at accelerating rate. World #1 CO2 polluter is China, and their annual "contribution" is increasing year after year. US of A is #2, no annual increase in the last few years.
CO - also no smell or color - comes without any flame and often without smoke. Poisonous.