Ozone Measurements in the Southern Part of Ticino

W. Landolt, P. Bleuler

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Site of Exposure

The measuring station lies in the hills above Chiasso, 600 m a.s.l., 350 above the valley floor. Its southern geographic position favors the ozone formation with its stronger radiation more than at sites north of the alps. In addition, emissions from the Gotthard traffic route and the Po valley provide the necessary precursors, nitrogen oxides and hydrocarbons.

Ozone: Does It Cause Leaf Symptoms?

Research teams from the WSL and the Pennstate University, supported by the Swiss Environmental Agency and the Canton of Tessin, are investigating visible symptoms on leaves of deciduous trees and shrubs since 1995. In Open-top-Chambers these symptoms are reproduced and verified. The ozone measurements presented here are an important tools for surveying the exposure conditions and thus acquire information about the reason and the development of the leaf injuries.

Ozone: 1-hr-Means (ppb)

In the graph next to this text, the actual hourly means of the ambient ozone concentrations up to the last three days are shown. In the project, there are 8 sampling sites within Open-Top-Chambers and one outside of them in the open air. The data are alternatively acquired all around the clock, with hourly calculations of the mean concentrations at each site. According to the measuring procedure, the hourly means are approximate values which may slightly differ from values derived from real 60 minutes intervals.

Ozone: Daily Means and 1-hr-Maxima (ppb)

The daily ozone means are represented by green, the maxima by red symbols. 
The ambient ozone concentrations  vary with the environmental conditions. The values are highest on sunny days and minor when it rains. Furthermore, rain cleans the air from precursors of the ozone formation, so that some time elapses after rainy periods until higher ozone peaks  appear again.