AQI is highly variable by locale and hour. It averages out in the end, but measuring regional and global emissions is a better way to compare disparate time periods, except for areas at the extremes.
To begin, it does accumulate in the region where it is created, but of course it diffuses over time, so 10 pollution could be 7 locally and 3 globally. The heavy elements (soot) never get very far and naturally fall out of the air. Some elements are broken down by sunlight. Some bind to rain and are washed into the ground. If pollution is constant, you reach an equilibrium in the air quality. Decreasing output slowly lowers that equilibrium and improves the air quality in the end.
Air pollution was worse in the last century https://ourworldindata.org/outdoor-air-pollution
Thanks for the informative response. I’m a bit confused by the graphs given, that track emissions and not air quality itself. Would you know why?
AQI is highly variable by locale and hour. It averages out in the end, but measuring regional and global emissions is a better way to compare disparate time periods, except for areas at the extremes.
I would expect emissions to cumulatively impact air quality, is that not the case?
To begin, it does accumulate in the region where it is created, but of course it diffuses over time, so 10 pollution could be 7 locally and 3 globally. The heavy elements (soot) never get very far and naturally fall out of the air. Some elements are broken down by sunlight. Some bind to rain and are washed into the ground. If pollution is constant, you reach an equilibrium in the air quality. Decreasing output slowly lowers that equilibrium and improves the air quality in the end.
Thanks, that’s very informative!