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Zurich
Environmental Situation
Because of the density of environmental polluting activities cities and their agglomerations
are especially affected by air pollution. As a result of the implemented measures on all
federal lev-els (communities, cantons and the Swiss federation) to control the air pollution,
the air quality has substantially improved over the last decades. Essential differences still
exist in the extent of air pollution. So the measured values increase in parallel to the
population density, with the traffic density as the decisive factor. Even 20 years after
coming into force of the Swiss ordi-nance on air pollution control (OAPC) the limits of
the OAPC are often exceeded. Above all, particulate matter (PM10), nitrogen dioxide (NO2)
and ozone (O3) cause problems. Main reason for the excessive load of these pollutants is
the motorised traffic.
In the centre of town and along the main traffic axes the limit for nitrogen dioxide
(30 µg/m3 - annual mean) is exceeded. For particulate matter PM10 (limit for the annual
mean: 20 µg/m3) this applies to nearly the whole habituated area of town. O3 substantially exceeds
the limit (1 hour > 120 µg/m3 in a year) over the whole town area.
Disquieting in relation to the air pollution development is the fact of a rising fraction of diesel
cars in newly sold private cars over the last years, from 5% in the late nineties to 25% nowa-days.
This may lead to a new increase of air pollution levels, which have been stagnating in the last years.
First signs in the course of measured values show hints to this possibility.
Due to the taken actions to reduce sulphur dioxide and carbon monoxide the situation has im-proved
in a way, that they pose no problem anymore. All limits and regulations for these pollut-ants are kept.
For non regulated pollutants, for example benzene, an improvement of the situa-tion could be achieved
by reducing the benzene content of gasoline and the disappearance of older cars without catalytic
exhaust reduction systems.
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