Air cleaners may not take care of second hand smoke:

Air purifiers DO NOT reduce the exposure to secondhand smoke. Best is not to allow smoking in your vicinity on the occasion of World No Tobacco Day.

Various devices are available for air cleaning, ranging from systems that are incorporated into the heating, ventilation, and air conditioning to simple table top devices and "smokeless ashtrays.

But cleaning air of second hand smoke poses a technical challenge because of the tobacco smoke as well as gases and particles that are included in second hand smoke.

Air cleaning devices typically include filters or electrostatic precipitators to remove particles. Some devices, also include a sorbent, such as activated charcoal, to remove gases. For second hand smoke both elements are needed.

For any air cleaning device to be effective, it must be able to clean a sufficient volume of air in relation to the total volume of the space where it is operating. Few devices are able to clean sufficient volumes of air to be effective in managing smoking indoors.

Small devices, like smokeless ashtrays and many table-top units, offer completely inadequate cleaning capacity.