Thimphu, Paro, Punakha, Wangdue, Haa and Bumthang – all of these towns and cities are natural bowls in which high levels of particulates remain trapped and suspended. Unlike in the plains where the pollution is dispersed by wind activity, high mountains that box in our valleys do not permit air circulation – preventing both vertical and horizontal mixing of polluted air with that of clean air in the upper atmosphere.
Thimphu valley: enveloped by trapped and suspended particulates; as seen from Phajoding
During the winter months, temperature inversions trap tiny particles of smoke and exhaust from cars, trucks, bukharis, and anything else that burn fuel - whether fossil or otherwise. This keeps the pollution close to the ground - right where the precious Drukpas are breathing.
When we begin to have pollution problems in our valleys, remember the problem will be 20-30 times worst than those in the plains.