Air pollution in Hong Kong is getting more serious. It seems that we are seeing more and more grey skies recently. The air quality is so poor, there are days when we may even find it hard to breathe. Many people wear protective masks when the air quality is poor. But the Centre for Health Protection says that, in fact, these protective masks have barely any effect in protecting us from inhaling pollutants such as carbon monoxide, nitrogen dioxide, ozone and sulfur dioxide.

This is because most protective masks cannot filter particles of 10 microns or below. And it's not much better when you get home. Unfortunately, studies show that air pollution in some homes may be just as serious as in the streets. So a home air purifier is really important. However, with so many different types available on the market, which one is right for you? Check out the following tips.

Clean Air Delivery Rate (CADR)：
All certified products imported from the U.S. have a CADR value, which is a standard set by the U.S. National Electrical Manufacturers Association. This is the speed at which an air purifier eliminates different pollutants. The higher the value, the faster it cleans pollutants.　
Applicable area：
Select an air purifier according to the applicable area. The larger the volume, the stronger the filtering capacity. But please note before buying that the larger the applicable area listed does not necessarily mean a better the result. For small rooms, a mini tabletop air purifier is sufficient while for large living rooms, a floor-mounted one is more suitable.　　
Purification methods and technology：
Different air purifiers offer different air purification methods and filtration technologies. Select one according to your needs.　

1. HEPA Filter：
This is the most common type of filter. It targets dust mainly by absorbing fine particles in the air. It blocks up to 99.7% of dust particles down to as small as 0.3 microns.　
2. Activated carbon：
This filter is effective in eliminating odours and harmful chemicals and lasts for about three months to six months.
3. Negative ions：
Usually used in conjunction with a HEPA filter, these combine odour substances and when negative ions come into contact with the dust in the air, the ions combine with the dust particles and fall to the ground.
4. Photocatalyst：
Effective against bacteria and viruses. The UV light stops bacteria from decomposing, but cannot kill them. It simply reduces the amount of bacteria in the air so the effect is relatively limited.　
5. Electrostatic：
Mainly targets dust via electrostatic positive and negative phase suction to achieve the effect of absorption and dust removal.

Air Purifying Technology