Photochemical smog

However, to#nbsp;understand the causes of#nbsp;the increased content of#nbsp;particulates in#nbsp;the air and to#nbsp;develop strategies for their reduction, it#nbsp;is#nbsp;also important to#nbsp;measure the concentrations of#nbsp;some gases.

The matter is#nbsp;that fine dust particles are not only caused by#nbsp;the destruction of#nbsp;automobile tires or#nbsp;other direct methods, but they also appear as#nbsp;a#nbsp;result of#nbsp;photochemical reactions between nitrogen oxide and volatile organic compounds. That means, to#nbsp;get rid of#nbsp;smog, we#nbsp;need to#nbsp;understand the sources of#nbsp;nitrogen oxide and decrease their concentrations. That is#nbsp;why, when cities approach us#nbsp;with requests for PM2.5 monitoring, we#nbsp;offer to#nbsp;start controlling the content of#nbsp;gaseous mixtures in#nbsp;the air as#nbsp;well, even if#nbsp;the end goal is#nbsp;to#nbsp;eliminate smog.

The phenomenon of#nbsp;photochemical smog was discovered in#nbsp;the early 1950s by#nbsp;Dr. Arie Jan Haagen-Smit when he#nbsp;was studying air quality issues in#nbsp;Los Angeles. Before this research, the city’s enterprises had been closing one after another as#nbsp;they had been blamed for the awful state of#nbsp;the atmosphere in#nbsp;the city. But it#nbsp;had still been hard to#nbsp;breathe, and on#nbsp;the worst days, one could not even see the next quarter due to#nbsp;smog. After Dr. Haagen-Smit's discovery and the systematic actions of#nbsp;the government towards pollution mitigation, the air quality in#nbsp;Los Angeles has been considerably improved.