India, June 21 -- Just when we had begun to internalise the deadly impact of increasing levels of particulate matter and nitrogen dioxide from toxic fumes, usually in winter, Delhi now has a new pollution threat from ground-level ozone. A recent study by the Centre for Science and Environment (CSE) has pointed out to what could become a new summertime hazard with noxious emissions by the city's vehicular fleet and industrial units combining under severe heat conditions to form polluting or bad ozone, which is very different from the good ozone in the stratosphere that cuts out ultra-violet rays. The CSE has warned that this complex atmospheric chemistry needs investigation and immediate action as ozone dominance has been found to be stubb...