Visit any city in the world and you ’ll see grimy old buildings . The grime and miscellaneous subatomic particle that inevitably accumulate and become embedded in punishing urban surfaces seems to be a natural symptom of urban center liveliness . But new research suggests that we may want to revisit what we thought we knew about grunge .
Scientists have long theorized that grime ( a mixture of thousands of chemical substance compounds emitted by cars , motortruck , and factories ) trap in topographic point chemical substance compound like atomic number 7 oxides , which can combine with volatile organic compound to make ozone , the main part of smogginess . To test this possibility , researcher result by University of Toronto chemistry professor James Donaldsonstudied the filth on a rooftopin Leipzig , Germany , both in the sunlight and in the masking of shade , by leave trays filled with windowpane glass bead on the construction for six weeks . ( Because they have more surface area , the field glass beads can accumulate more dirt than a prostrate surface like a window can . )
The research worker find that the beads place in the sun carry 10 percent less nitrate than the shaded astragal . “ Rather than being a lasting sink for nitrogen oxide gun , stain exposed to sunlight can re - loose some of these gases back into the urban atmosphere , ” Donaldson explained at an American Chemical Society conference in Boston .
These finding are consistent with finding Donaldson and his team had previously made in the science laboratory . The musical theme that grease may be have urban center strain even risky than we think is troubling . “ If our suspicions are right , it means that the current understanding of urban gentle wind pollution is miss a large chunk of information,”Donaldson say . In their continuing research , he and his squad contrive to convey like psychometric test in very dirty and very clean cities . They also want to learn how humidity and vary degree of sunshine photo lend to the problem .
