A sales associate prepares aromatic oxygen flasks at the "Oxy Pure" bar in New Delhi, Nov. 22, 2019. An outlet in the highly polluted capital city sells residents a lease of what it claims "pure oxygen". (Photos: Xinhua)

A sales associate serves a customer at the "Oxy Pure" bar in New Delhi, Nov. 22, 2019. An outlet in the highly polluted capital city sells residents a lease of what it claims "pure oxygen".

A customer (L) makes enquires at the "Oxy Pure" bar in New Delhi, Nov. 22, 2019. An outlet in the highly polluted capital city sells residents a lease of what it claims "pure oxygen".