The more researchers learn about wildfire smoke, the more worrisome the picture gets. Smoke contains microscopic particles known as PM 2.5 because the PM (particulate matter) measures 2.5 microns or less — small enough to easily wiggle its way into our lungs and then into our bloodstreams. Researchers have already connected the particulate matter in wildfire smoke to a higher risk of strokes, heart disease, respiratory disease, lung cancer and other serious conditions. And the harmful effects don’t stop there. 2024 was a banner year for research on wildfire smoke and its impact on health, from brain functioning to fertility. While there’s still a lot more to learn, wildfire smoke is thought to be especially insidious compared to other sources of air pollution; its smaller particle size, intermittent spikes and higher concentration of inflammatory compounds make it more dangerous. This year’s new findings are disturbing. …New estimates predict 125 million Americans will face unhealthy air from wildfires by 2054.