I am non smoker, but am exposed to smoke (approx) 30 cigarettes per day at work. How does this affect my health?

Significantly. Second hand smoke has been proved to be a risk factor for lung cancer and other lung diseases. The risk increases linearly with increasing exposure. It also increases incidence of asthma, upper respiratory infections, and otitis media in children.
Call OSHA. In most workplaces, you are protected under federal (and sometimes state)laws and regulations from being exposed to second hand smoke. Being exposed to 30 cigarettes being smokes is not the same as smoking those yourself, but may well be the equivalent of 4-5/day, which can do harm. If your employer is unwilling to provide a smoke-free workplace, you may need to talk to osha or a lawyer.