Exposure to smoke in the areas around wildfire-prone forests is known to . However, surprisingly little is known about the exact mechanism by which this occurs. This is in part due to the complex nature of chemical reactions that occur as forests burn: Plants and trees are sophisticated living systems, and when they are subjected to the massive amount of heat in a fire, chemical reactions run wild, creating a myriad of combustion products.
Shedding light on this issue requires tracking not just individual chemicals but the interplay between mixtures of chemicals. For example, chemical X might affect our lungs in one way by itself but in another way when accompanied by chemical Y. In a new study published in Science of the Total Environment, from the University of North Carolina analyzed the smoke of five commonly burned biomass components (eucalyptus, peat, pine, pine needles, and red oak). They identified at least 86 different chemicals that could be released when those materials burn.
By tracking the relationships between these chemicals, the researchers discovered that the degree of toxicity of wildfire smoke depends on the type of biomass being burned, with pine being one of the least harmful. This is primarily due to the presence of a class of molecules called methoxyphenols, including (which gives vanilla its flavor). Even when harmful inorganic or ionic components like lead, chlorine, or phosphates were present in high amounts, methoxyphenols acted as protective agents, suppressing the negative effects. This can be helpful not only to identify which people living nearby are most at risk based on the composition of nearby biomass, but also to give clues to how adverse effects could be mitigated by a mindful selection of trees for reforestation.