Air purifier claims to be a device which removes particles like haze and viruses from the air. Is this true? Is air purifier effective in removing such particles? Can they remove odor from the air?
Air purifier with High-Efficiency Particulate Arrestance or HEPA (a standard set by US government for air filter to remove 99.97% of particles that have a size of 0.3 micron passing through it) can be pretty effective. With such level of filter, air purifier should be effective in removing both haze particles (which is typically measured by 2.5 micron under Singapore PSI reading) as well as air contaminants greater than 0.3 micron.
Though HEPA filters can possibly arrest very fine particles effectively, they do not remove gasses and odor. Air purifier with activated carbon or charcoal or other mechanism is necessary to remove gases and odor (e.g. smell from cigarette and pet). In addition, viruses which is usually less than 0.03 microns are likely to escape from the filtration. As such, air purification systems should have ultraviolet lights and electrostatic filters to be more effective in removing viruses.
Having said the above, air purifier (if chosen correctly) can be beneficial to you in an aircon room by removing fine particles from the air and prevent nasal problem and allergy and asthma.
Read more about staying indoor in the aircon room during haze season and aircon servicing in the form of aircon chemical cleaning, aircon steam cleaning and aircon overhaul.