Is the metro safe?
The Swiss Foreign Ministry rates the metro and metro buses as relatively safe. According to the German Foreign Office, though, pickpocketing is more common in crowded buses and trains at rush hour – keep your phone and wallet well stowed. At night, a taxi or ride-hailing app is the safer choice.
Source: https://www.eda.admin.ch/countries/brazil/de/home/reisehinweise/vor-ort.html ; https://www.auswaertiges-amt.de/de/service/laender/brasilien-node/brasiliensicherheit-201092