15. The exhaust pipe of a school bus shall(1) expel the exhaust from the rear of the bus or from the left side between the rear wheel and the corner of the rear bumper, except for a minibus where the pipe is located so that the exhaust is expelled from the right side, provided it is expelled behind the rear wheel;
(2) where located at the rear of the bus, extend beyond the body but shall not extend beyond the bumper by more than 2 cm; and
(3) be attached in such a manner that the exhaust is not directed underneath a door or a window that can be opened.