AIR contains 21% Oxygen (Sur), 78% nitrogen (Sur), and 1% impurities (Asur), argon, carbon dioxide, hydrogen being main impurities.
NOW..>this much Asur or impurities is SCIENTIFICALLY ACCEPTED, and air is PURE; but once the asurs increase their strength, the Devta gets weakened and Defeated. Today because of pollution air Devta is WEAKENED.\
When Sati sacrificed her life, TOTAL CHAOS ruled the world for millions of years. There was total Disharmony, or if one chooses to say complete disharmony ruled the world. Life as such could not exist. It was only after Himalayas became larger and taller , a new harmony was developed, and reasonable ratio of harmony and disharmony was developed(Balance/stability), life reappeared on earth.