Scientists have an array of analytical and computational tools to help monitor airborne pollutants like volatile organic compounds (VOCs). But researchers at Peking University, in China, and also the University of Colorado, Boulder, have discovered that  photochemistry occurring while a pollutant molecule travels from its source to a monitoring instrument can interfere together  with the accuracy of a well liked data analysis technique. Min Shao and colleagues used gas chromatography and mass spectrometry to check VOC emissions in  Beijing, relying on a data processing technique generally known as constructive matrix factorization (PMF). Even though some solutions in the similar class  as PMF attempt to take into account atmospheric photochemical reactions, such interferences inside the extra typically utilised  PMF strategy have not been well recognized. With regard to instance, with all the Beijing data, PMF failed to entirely separate  human and nonhuman VOC sources. The approach also mistakenly identified some VOCs as from separate sources, once they have been in fact from the same supply in distinctive oxidation states. The researchers caution that after utilizing PMFbased final results,  like these already reported in the literature, photochemical influences ought to be taken into account.

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