A qualidade do ar em Lisboa: valores medios e situacoes extremas

Abstract

Different aspects of the air pollution in Lisbon were analised: spatial distribution, cyclical variation (yearly, weekly and daily) and dependence on athmospheric conditions. During January 1993, when air pollution attained very high levels, we found that a strong relationship was established between air pollution and wind speed and direction as well as between air pollution and the height of the thermal inversion over Lisbon. During the more polluted periods, wind speed never reached 2 m/s and the thermal inversion was always under 165m. As for wind direction, pollution roses confirmed that the highest pollution levels occurred with a flux favourable to the transport of pollutants from the main emission areas.