Air pollution started to become a problem for human beings with the industrial revolution, but nowadays, with the introduction of laws against emissions (e.g., the EuroX normative), the situa- tion is getting better. Moreover, governments must constantly monitor pollution levels to check policies effects. This article describes a method to verify traffic ban effect claims on air pollution using monitored data. In Lombardia (our region), ARPA (the local EPA) maintains pollution monitoring stations from down- town Milano to remote places near the mountains since 1999. Measured data are “somewhat” available through ARPA’s website. “Somewhat” because a CAPTCHA protected download request form must be filled up for every combination of (station, pollutant, time-frame < 1 yr). In 2003 the Lombardia government introduced a vehicle ban to reduce air pollution. Then, more recently (in 2008 and 2012) the Milano City Council introduced a stricter ban. The author implemented an automated (in place since 2004) data collecting “web gatherer” to overcome ARPA’s overcomplicated download procedure and, above all, to verify air pollution reduction claims. Data are published on the author’s website and this paper presents a method to analyse effects on air pollution and to verify policies claims.

open data, public accountancy, pollution, particulate matter, anti-pollution policies, web scraping, vehicle banning