Cars registered before 2000 are not allowed within a certain part of the city centre between 7am and 9pm Mondays to Fridays, theoretically to help reduce pollution.
Francisco Ferreira, a professor at the Universidade Nova de Lisboa faculty of science and technology, said the air quality was due to emissions: “In the case of Avenida da Liberdade we are talking about road traffic” and weather conditions.
“What happened in 2015 is that there was a series of periods with less favourable weather conditions, periods of stagnation, without any wind and so we had a significant exacerbation in terms of air quality”, he said, adding that last year’s data is still not final.
Despite considering that “the weather conditions were the overriding reason”, the environmentalist did not exclude an increase in traffic on Avenida da Liberdade or that some old cars were still driving there.