The Piston Effect
Scientists and engineers
around the world are becoming aware that the United States 8-hour
ozone standard is presenting a problem that is called "unattainability."
Over 20 years ago, the unattainability issue was discussed by
Dr. Lefohn, President and Founder of A.S.L.
& Associates. In November 1998, the topic was discussed
at an international meeting in Beijing, China by Dr. Lefohn.
Policymakers are now finding that the 8-hour ozone standard will
be difficult to attain and control strategies will not work as
planned as lower and lower standard levels are promulgated. Mid-range
hourly average concentrations decline slower than the higher
hourly average concentrations and make it difficult to attain
the lower standards. Independent analyses have confirmed the
"piston" effect. Two publications (Lefohn et al., 2017;
Lefohn et al., 2018) identify how the "piston" effect
influences ozone monitoring sites in the EU and the US. Watch a slide presentation of the "piston"
Lefohn, A.S., Malley, C.S., Simon,
H., Wells. B., Xu, X., Zhang, L., Wang, T., 2017. Responses of
human health and vegetation exposure metrics to changes in ozone
concentration distributions in the European Union, United States,
and China. Atmospheric Environment 152: 123-145. doi:10.1016/j.atmosenv.2016.12.025.
Lefohn, A.S., Malley, C.S., Smith,
L., Wells, B., Hazucha, M., Simon, H., Naik, V., Mills, G., Schultz,
M.G., Paoletti, E., De Marco, A., Xu, X., Zhang, L., Wang, T.,
Neufeld, H.S., Musselman, R.C., Tarasick, T., Brauer, M., Feng,
Z., Tang, T., Kobayashi, K., Sicard, P., Solberg, S., and Gerosa.
G. 2018. Tropospheric ozone assessment report: global ozone metrics
for climate change, human health, and crop/ecosystem research.
Elem Sci Anth. 2018;6(1):28. DOI:
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