For weeks now, wildfire smoke from massive fires in the boreal forests of Canada have spread over swaths of the U.S. On July 18 and 19, parts of the East Coast were once again shrouded in haze with air quality readings spiking towards unhealthy. Yearly exposure to wildfire smoke is likely to be the new normal for large parts of the U.S., Europe, and Asia going forward. 

While we know that wildfire smoke isn't healthy for older people, those suffering from many medical conditions, and young children, we don't really know how unhealthy it is, exactly. Despite the fact that humans have lived with smoke since we discovered fire, there are many unanswered questions. Augustin Guibaud, a leading expert at University College London in the field of fire and smoke dynamics, addresses what we don't know about wildfire smoke's health impacts, what kind of health risks we should be watching for, and why more research is urgently needed.