It was merely a word of caution mostly towards the runners' health, there were several days last year when the AQI was the second worst in the planet (just behind either "somewhere" in China or Lahore), in a nutshell you don't want to get stuck in this part of the world during winter.

On a curious yet still foggy note (), SJJ is only CAT I (with no imminent prospect of going any higher due to runway "struggle"), this routinely leads to a hefty amount of delays and indeed cancellations during winter months...

G