Does this sign allow hydrogen-powered vehicles to enter the green transport zone?

In the picture there is a white rectangular sign with the word "Strefa" (zone) and a green circle with a car symbol - D-54 "green transport zone" (strefa czystego transportu). Beyond this sign, a hydrogen-powered vehicle may enter the zone. The answer is: yes.

The Regulation on road signs and signals states that sign D-54 "green transport zone" marks the entry to a green transport zone. Who may enter it is decided by the Act on Electromobility and Alternative Fuels: under this Act, electric vehicles, hydrogen-powered vehicles and natural gas vehicles may enter the zone, as well as vehicles exempt from the restrictions, for example vehicles of the Police, the fire service, the rescue services or of persons with disabilities; the municipal council may also allow other vehicles in its resolution, usually combustion-engine vehicles that meet a specific emission standard. A hydrogen car does not emit exhaust fumes, so it is one of the three types of vehicles for which the zone is always open, regardless of the content of the resolution. Before entering a town with such a zone, you check the rules for your vehicle on the municipality's website; the law provides for a fine for entering without permission.

Legal basis: § 60d of the Regulation on road signs and signals; Art. 39 of the Act on Electromobility and Alternative Fuels