Does this sign indicate entry into a 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). This sign marks the entry to a green transport 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, and sign D-55 "end of green transport zone" marks the exit from it. A green transport zone is created by the municipal council by a resolution under the Act on Electromobility and Alternative Fuels, to reduce exhaust emissions in city centres; the zone may be entered by electric vehicles, vehicles powered by hydrogen and natural gas, and combustion-engine vehicles that meet the conditions set in the resolution, for example a Euro emission standard, as well as vehicles exempt by law, such as vehicles of the Police, the fire service and the rescue services, or of persons with disabilities. The sign is easy to remember: the green circle means a "green" zone. Before you enter a city with such a zone, you check whether your car meets the requirements of the resolution; the law provides for a fine for entering with a vehicle that does not meet the conditions. The version of the sign with a line through it, D-55, means the end of the zone.

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