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Chemistry Laboratories

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Updated ozone absorption cross section will reduce air quality compliance

E.D. Sofen1, M.J. Evans1,2, and A.C. Lewis, ACP, 2015
DOI: 10.5194/acp-15-13627-2015

http://www.atmos-chem-phys.net/15/136 27/2015/

Photometric ozone measurements rely upon an accurate value of the ozone absorption cross section at 253.65nm.

This has recently been re-evaluated by Viallon et al. (2015) as 1.8% smaller than the accepted value (Hearn, 1961) used for the preceeding 50 years.

Thus, ozone measurements that applied the older cross section systematically underestimate the amount of ozone in air.

We correct the reported historical surface data from North America and Europe and find that this modest change in cross section has a significant impact on the number of locations that are out of compliance with air quality regulations if the air quality standards remain the same.