If you're considering buying an air purifier, you have a multitude of choices. But if you want an air purifier that will eliminate cigarette smoke, you're out of luck. Most air purifiers, also called air cleaners, are not designed to remove gaseous pollutants, which are a major component of cigarette smoke.
Mechanical air filters, such as high-efficiency particulate air (HEPA) filters, and electronic air cleaners, such as ionizers, target particles, but tobacco smoke particles are designed to be small enough to be inhaled into the outer reaches of the lungs and, thus, are not trapped by such devices.
Other air cleaners generate ozone, which is actually a lung irritant. At levels that don't exceed public health standards, ozone has little ability to remove air contaminants such as cigarette smoke.
The best way to protect nonsmokers from secondhand smoke is to not allow smoking in your home. If you smoke, this is another good reason to stop.