What's going on in Sierra Leone?
All the air quality maps show a huge amount of emissions that seems to suggest a ton of stuff is burning. I can't find anything else about this on the internet. Is it forest fires? If so, why are the emissions greater than that of all major Chinese cities?
The high rate of pollution by NO2, CO and PM2.5 is probably due to wide scale fires.
Check with Active fires layer on Windy:
This article is 5 days old but confirms extensive fires in Sierra Leone
Farmers in most of tropical Africa use fire to clear bush land for crop planting, just before the start of the main rain season.