How did thin air & high humidity force Bhutan to reject India's E20 petrol supply?

Bhutan has declined India's offer to buy ethanol-blended petrol, citing a lack of proper storage facilities for a hygroscopic fuel that easily absorbs water from the atmosphere. Bhutan stores a vast majority of its fuel at high altitudes on mountainous terrain. Stopping moisture penetration and the entry of atmospheric moisture in these humid conditions with thin air is very tough.