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.