Anthropogenic impact on the atmosphere's oxidizing power

Oxidation is the key atmospheric chemical process responsible for removal of thousands of tons of man-
made pollutants released into atmosphere each day.  The entrusted chemical agent that keeps up the
oxidation process going is the hydroxyl radical (∙OH), a short-lives molecular species of natural
abundance ~10^6 radicals/cc.  The primary source of atmospheric hydroxyl radical is a photochemical
reaction between the trace quantity of tropospheric ozone transported from the upper atmosphere and
water vapour in our surroundings.  The measurements reveal that in spite of many fold increase of the
pollutants level in recent year since the pre-industrial age, the globally averaged atmospheric
concentration of hydroxyl radical has remained almost intact. Thus, there are parallel processes of
oxidations, which recycle the hydroxyl radical and allow continuation of the atmosphere’s self-
cleansing activities.  The understanding developed through laboratory investigations of this apparent
miracle will be discussed with a view of the atmosphere’s future stability against the threats of the
burgeoning anthropogenic activities.