HGVs and buses over 3.5 tonnes are affected by the Swedish LEZs.

The basic rule is that heavy trucks or heavy buses may drive in a low emission zone for six years from the first registration. The year of the registration doesn't count.
Since 1 January 2021 the vehicles mentioned above have to meet Euro 6 standard to be allowed to enter the low emission zones. 

Exempted form that rule are vehicles that meet Euro 5 standard and have either been registered after 2013 or 2014. These vehicles are allowed to enter the LEZ until 2021 or respectively 2022.

Sweden has low emission zones in Göteborg, Helsingborg, Lund, Malmö, Mölndal, Stockholm, Umea and Uppsala.

Source: Pixabay, robertaengland