I live in Utah where all the smoke from the west-coast wildfires likes to come take up residence, and I can't recall more than a single summer before 2015 when wildfire smoke was pervasive outdoors. But in just the past few years it seems that a good 50-80% of the summer the air outside is completely unbearable due to smoke.
I can't be making this up, this must be a recent phenomenon. But my Google-fu is failing me in trying to find a chart that confirms my intuition. I'm curious: what changed, and when exactly did this new trend begin?