mix of dirty air, high humidity, high temperatures cause for increase of pimples

With a little help from dust and air pollution, sweat, and body oils, high humidity creates a breeding ground for acne causing bacteria.

If you sweat it's a good idea to use a clean wet cloth on your face and neck a few times during the day.

The word which appears frequently in tropical climates applies here: HYDRATE.  It can work against you creating more sweat and may require more face washing

Managing acne in humid weather | Schlessinger MDส
Unmasking the Relationship Between Humidity and Acneกลนคร Sakon Nakhon