In technical terms, Desert Coolers are called Evaporative Coolers, and I am therefore attaching that portion of the ISHRAE document issued on 13 th April. The guidelines are very simple:
1. The Cooler Tank must be kept clean and disinfected and water be drained and refilled frequently.
2. Keep a house window open to release humid air.
3. Do not use portable coolers that do not draw air from the outside.
Stay safe and cool. Thanks.