A woman is seen wearing face mask in Warsaw, Poland on April 18, 2020. Poland has named four stages in which the restrictions will be gradually lifting, starting with the opening of parks and forests, and ending with services that require physical contact. (Xinhua/Jaap Arriens)

A man is seen wearing face mask in Warsaw, Poland on April 18, 2020. Poland has named four stages in which the restrictions will be gradually lifting, starting with the opening of parks and forests, and ending with services that require physical contact. (Xinhua/Jaap Arriens)

A family is seen wearing protective masks in Warsaw, Poland on April 18, 2020. Poland has named four stages in which the restrictions will be gradually lifting, starting with the opening of parks and forests, and ending with services that require physical contact. (Xinhua/Jaap Arriens)