A plume detected Dec. 21 was the second-worst concentration of the gas attributed to coal mines in China last year, according to Kayrros.
![](https://staging.kayrros.com/wp-content/uploads/2022/01/Screen-Shot-2022-01-31-at-16.25.56.png)
A plume detected Dec. 21 was the second-worst concentration of the gas attributed to coal mines in China last year, according to Kayrros.