Air cleaner and filters for allergies and sensitivities

Very Important: An air cleaner is only able to "polish" the air, it can not make a bad place good, no matter how big an air cleaner you buy. If you are allergic to a pet, get rid of it, or at least restrict it from the bedroom. Tough, but you can't mechanically fix thing, seriously. I've seen air cleaners the size of a small desk, and how little effect they had when trouble showed up.

You can get air cleaners from several mail-order companies as well as Kmart, Target and larger department stores and hardware stores. Look for those with the HEPA label, which guarantees the efficiency and longevity of the filter.

Watch out for labels claiming "HEPA-like" performance, the claims are not reliable, as they do not conform to a standard test.

If you have problems beyond dust and pollen, do not waste your money on any of the models you can presently buy in any store. They are simply not enough, even though they say they have carbon filters to 'remove odors'. It's a complete waste of your money. See here below for more information.

As a general rule, buy much larger than you think you need. If an air cleaner can do 250 cubic feet per minute, it's better to run it at a lower setting because of the noise, and the life of the machine. If you need 250 cfm, buy a 350 cfm machine instead. Also, you may need the extra capacity when there is trouble.

standalone air cleaner

The most common air cleaner is the standalone, that simply plugs into a wall outlet, and can be lugged from room to room. These air cleaners are great for cleaning the air in a single room, they have little effect on adjacent rooms.

Make sure to get one large enough for the room, it should be able to clean the room six times per hour. If your room is 20 feet by 12 feet and 7 feet tall, you have (20 x 12 x 7 = ) 1680 cubic feet. To clean it six times an hour, you will need a machine rated for at least 168 cubic feet per minute (1680 x 6 / 60). You will need one for each room.

Get one that is larger than you need, then you can run it at a lower speed, which both cuts down on noise and lets the motor live longer. One I have (a Honeywell) has been running for a couple of years and the bearings are worn a noisy. It helps that I put it upside down.

Filters on registers

In houses with forced-air heating/cooling, dust can collect in the air ducts, which is hard to remove. To catch the dust that does come loose, you can put a filter on each of the registers, at least in the bedroom. Some flimsy material to cut to size is sold by several companies. I use the "Holmes HEPA+" filter model HAPF-30 (made for a small table filter) and tape them over each register, works great.

WARNING: If you use a small heat pump, it may overheat. The filters restrict the airflow a bit, causing the coil to be hotter. If you notice the heat pump to have problems, take the filters off, or run it on emergency heat only. If the coil bursts, the freon will be coming out of the registers in the whole house, and you may suffocate!

Furnace filters

Many hardware stores sell reusable furnace filters, which you can wash once a month. They are many times better than the flimsy $1.50 filters most people use. It will cost you about $35, but will last up to ten years. They even have do-it-yourself filters you can cut to fit odd size furnaces.

If your are chemically sensitive, you can purchase carbon filters to put in your furnace, they cost about $35 and last 4-6 months. See the company list.

Carbon and zeolite filters

Many air filters now come with a small activated carbon filter. These are completely ineffective, they are worthless in my opinion. It takes several pounds of carbon and zeolite to be effective.

Carbon filters alone are not effective against a lot of chemical compounds that we encounter indoors. Activated carbon filters are only effective for large molecules, and is best for gases with a high boiling point. A rule of thumb is that carbon filters poorly absorbs molecules with less than three atoms, besides hydrogen. This makes them unsuitable for ammonia (NH3), ethylene (C2H4), formaldehyde (CH2O) and acetylene (C2H2). (This information is borrowed from the book "Glent Klimateknik" by Ole Stampe, published by Glent & Co in Copenhagen, Denmark).

Zeolite filters are more effective against these compounds. Good filter systems use both. Again, it takes pounds of this to be effective.

I know of three manufacturers that makes reputable air cleaners: E. L. Foust, Austin Air and Allermed. These machines cost $200-$400, anything less is a toy, in my opinion.

Gasmasks

For those times when you to have to enter places that are not healthy for you, you can use a mask. For simple things, like doing laundry, I use a simple dust mask.

To go into an area that have recent carpeting, I use a 3M mask with the optional organic vapor filter (it regularly comes with a HEPA filter). This mask is available from several of the allergy supply firms. The mask is made from latex, so you might want to wash and air it out before use.

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