Like so much else in 2020, the wildfires engulfing the western half of the United States are without precedent.They have advanced with astonishing speed, leaping 25 miles overnight and sending a towering pillar of smoke into the stratosphere. At this writing, the blazes have claimed at least three dozen lives, burned more than 5 million acres and forced hundreds of thousands of people from their homes.The fires have also sparked a public health crisis. Much of the western U.S. and Canada is wreathed in acrid smoke, resulting in some of the world’s worst air quality. Wildfire smoke exacerbates …