When we talk about air purifiers we generally restrict our discussion to particulates suspended in air. But it is not just about them. Air inside the home might have odors not particularly pleasing to your olfactory senses. You need to deal with them too. Good news is that there are air purifiers which come with gas purifiers.
Generally carbon is used for gas filters. And it can be anything from coal based filters to coconut shell based ones. The carbon filters work by absorbing gas molecules in their pores. So all the gases that produce those nasty odors are trapped inside the pores and are not allowed to circulate in the air. To remove the VOCs and SVOCs activated carbon filters will be the best solution since they are of higher molecular weight. But there are drawbacks with carbon filters. They are not that functional when working in humid conditions. The water is filled with large molecules of water vapor and they get absorbed by the pores. Carbon also fails to deliver in case of gases with lower molecular weights like formaldehyde, sulfur and nitrogen dioxide. For such specialized cleaning there has to be dedicated gas control ingredients like Chemisorbers. They chemically remove gases from air. Chemisorbers actually react both with the gas molecule and the water molecule and subsequently produces odorless, harmless gases like carbon dioxide. The well known Chemisorbers are alumina oxide, alumina silicate, and potassium permanganate. A better gas filter would be on which has more pores as it will mean more gas can be absorbed by the filter. So it will absorb better and last longer. It is only when all the pores are saturated that you would need to change the filter.
A gas filter should be preceded by a pre-filter. Without the pre-filter the gas filter will lose its efficiency significantly. The micro pores in the gas filter, supposed to absorb gases will be filled with air particulates. This will mean that your filter will soon get saturated and it would require a replacement.
To get the best air purifier for yourself is no mean task as there are a variety of them and the technology behind them is also different. The job of an air purifier is to clean the air of all its pollutants and that would include allergens, particulates, gases, etc. following is a comparison between the three main kinds of air purifiers that are ruling the roost in the purifier market.
Also larger the surface area of the filter, the better will be the absorption of the gases.
Now we know, it is not enough to have particulate filters. However good a HEPA air purifier you have, if it doesn't come with a gas filter, you will still be breathing in polluted air from your room.
