Air pollution in cities
Air pollution path in the atmosphere
Temporal variability of air pollutants
Assessment of air pollution
Trends of air pollutants
Motor traffic
Industry
Power plants
Trade
Domestic fuel
Motor vehicle traffic seems to be
the most important source group for air pollution
Since 1950, the global vehicle fleet has grown tenfold, and is estimated to double again within the next 20-30 years.
As cities expand, more people will drive more vehicles over greater distances and for longer time
Emissions of air pollutants by motor tra$c depends on different factors such as traffic density, driving habits or ratio of automobiles to trucks.
Dispersion and dilution of air pollutants
Are strongly influenced by meteorological conditions, especially by wind direction, wind speed, turbulence, and atmospheric stability.
Topographical siting and urban structures like street canyons,for example, have a great e!ect on these meteorological parameters.
Ozone is partly produced in the lower troposphere by the
action of short-wave radiation on anthropogenically released precursor substances
The patterns of temporal variability of air pollutants can be found in cities world-wide.
Sometimes they are modified by local circulations like sea breeze oflws or short-time meteorological effects, but the basic structures are preserved.
The level of air pollution is different in different cities. It depends on the background air pollution, specific emission conditions, general meteorological conditions and location of the air quality station within the city.
Time series of air pollutants indicate trends in air pollution.
In cities of non-industrialised countries, time series of air pollutants are often too short for statistical trend analysis.
Modifications are possible, if only selected seasons, specific urban structures or specific emission conditions are analysed.
Seen on a global scale, there exist more and longer time series for SO2, TSP and smoke than for air pollutants that are typical of motor traffic.
Exposure to elevated concentrations of ambient air
pollutants causes adverse human health effects.
Must know
How severely is health affected
Location-specific
Appropriate indexes for the assessment of the air-quality
Whether the air in cities is unhealthy