Tropospheric Ozone Assessment Report: Present-day ozone distribution and trends relevant to human health
Artikel i vetenskaplig tidskrift, 2018

This study quantifies the present-day global and regional distributions (2010-2014) and trends (2000-2014) for five ozone metrics relevant for short-term and long-term human exposure. These metrics, calculated by the Tropospheric Ozone Assessment Report, are: 4th highest daily maximum 8-hour ozone (4MDA8); number of days with MDA8 > 70 ppb (NDGT70), SOMO35 (annual Sum of Ozone Means Over 35 ppb) and two seasonally averaged metrics (3MMDA1; AVGMDA8). These metrics were explored at ozone monitoring sites worldwide, which were classified as urban or non-urban based on population and nighttime lights data. Present-day distributions of 4MDA8 and NDGT70, determined predominantly by peak values, are similar with highest levels in western North America, southern Europe and East Asia. For the other three metrics, distributions are similar with North-South gradients more prominent across Europe and Japan. Between 2000 and 2014, significant negative trends in 4MDA8 and NDGT70 occur at most US and some European sites. In contrast, significant positive trends are found at many sites in South Korea and Hong Kong, with mixed trends across Japan. The other three metrics have similar, negative trends for many non-urban North American and some European and Japanese sites, and positive trends across much of East Asia. Globally, metrics at many sites exhibit non-significant trends. At 59% of all sites there is a common direction and significance in the trend across all five metrics, whilst 4MDA8 and NDGT70 have a common trend at similar to 80% of all sites. Sensitivity analysis shows AVGMDA8 trends differ with averaging period (warm season or annual). Trends are unchanged at many sites when a 1995-2014 period is used; although fewer sites exhibit non-significant trends. Over the longer period 1970-2014, most Japanese sites exhibit positive 4MDA8/SOMO35 trends. Insufficient data exist to characterize ozone trends for the rest of Asia and other world regions.


present day


human health




Zoe L. Fleming

University Of Leicester

Ruth M. Doherty

University of Edinburgh

Erika von Schneidemesser

Institute for Advanced Sustainability Studies (IASS)

Christopher S. Malley

Natural Environment Research Council (NERC)

University of York

University of Edinburgh

Owen R. Cooper

University of Colorado at Boulder

NOAA Earth System Research Laboratory

Joseph P. Pinto

The University of North Carolina at Chapel Hill

Augustin Colette

Institut National de l'Environnement Industriel et des Risques (INERIS)

Xiaobin Xu

Chinese Academy of Meteorological Sciences (CAMS)

Meteorologisk institutt

Martin G. Schultz


Forschungszentrum Jülich

Allen S. Lefohn

ASL & Associates

Samera Hamad

University of Maryland

Raeesa Moolla

University of Witwatersrand

Sverre Solberg

Norsk institutt for luftforskning (NILU)

Zhaozhong Feng

Chinese Academy of Sciences

David Simpson

Rymd-, geo- och miljövetenskap, Mikrovågs- och optisk fjärranalys, Global miljömätteknik och modellering

Elementa: Science of the Anthropocene

2325-1026 (ISSN)

Vol. 6 12