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Advisor(s)
Abstract(s)
Ozone (O3) is a secondary pollutant mainly produced in the troposphere by
photochemical reactions with high impact on human health. In this work hourly
average O3 concentrations from the Portuguese air quality network collected
during 24 years (1988–2011) were analysed. The background time series were
assessed by environment type (urban, suburban and rural) and considering
several criteria: the annual mean O3 concentration, the Directive 2008/50/EC O3
long-term objective and the 2005 WHO Guideline for protection of human health
and, finally, the hourly information threshold exceedances. The trend of annual
mean O3 concentration data and the maximum daily eight-hour mean ozone
concentration data were both annually compared using an one-way ANOVA
followed by a Tamhane post-hoc comparison test. In both series, although of an
instable trend, a tendency for an increase of the mean O3 concentrations was
found. On the other hand, after 2006, for all stations types, the normalized
number of exceedances for public O3 information are significantly decreasing
(p<0.05). In this paper, the O3 trend will be analyzed and discussed, contributing
to improve knowledge of long time series of O3 concentrations in Portugal.
Description
Keywords
Tropospheric ozone Background stations Time series Trends Exceedances
Citation
Publisher
WIT Press