The small particles produced when we burn wood can get deep into our lungs and lead to a range of respiratory and cardiovascular problems, including heart disease and cancer. We know that early humans were exposed to these pollutants because we find them in their remains from hundreds of thousands of years ago. When researchers looked at the preserved teeth of hunter-gatherers from Qesem Cave in Israel from 400,000 years ago they found pollutants from charcoal in them.12 These pollutants, they suggest, came from indoor fires for the roasting of meats.
