No person shall on a public road -
(a) drive a vehicle; or
(b) occupy the driver’s seat of a motor vehicle the engine of which is running,
while the concentration of alcohol in any specimen of blood taken from any part of his or her body is not less than 0,05 gram per 100 millilitres, or in the case of a professional driver referred to in section 32, not less than 0,02 gram per 100 millilitres.