Can an air filter weaken your immune system?
July 29, 2007 7:11 PM   Subscribe

Can an air filter weaken your immune system?

We've all heard of the studies where kids who grew up eating things off the floor grow up with stronger immune systems, kids growing up in a sheltered clean environment developing allergies and asthma, doctors who are all but immune to common diseases, and the like.
My question springs from stories/studies like these. I live in a fairly dusty area and am considering getting an air filter so I don't have to clean of a layer of dust every other week or so to keep my room tidy. Would getting this air filter lower the level of contact to pathogens so much that my immune system begins to atrophy?
posted by mwang1028 to Health & Fitness (7 answers total) 1 user marked this as a favorite
Most of the pathogens in your room, you probably brought there with you. Assuming you're not holed up in said room, Howard Hughes-style, you'll probably get plenty of exposure elsewhere.

Of course, if you're still worried, just start eating off of the floor.
posted by IvyMike at 7:26 PM on July 29, 2007 [1 favorite]

The "sheltered clean environment" could very well have seriously high loads of dust mites and the like. Just because it's "indoors" doesn't mean that it's "clean." High dust mite loads has been associated with allergies & asthma (just the first article that caught my eye, I'm sure you can find many more).

The air filter is a good idea.

Getting your kids outdoors and exercising is another great idea.
posted by porpoise at 7:27 PM on July 29, 2007 [1 favorite]

Most of the dust in your house is just your own shed skin cells or the skin cells from the rest of the people in your family and pets. I would get the filter.
posted by lockle at 7:53 PM on July 29, 2007

The Hygeine Hypothesis, which is what you're referring too, is a theory that emerged from the observation that, in the last 50 years or so, allergies and autoimmune disorders (MS, Crohns' Type I Diabetes, Asthma etc.) increased in western countries as the incidence of disease dropped (TB, Measles, Mumps, Rheumatic Fever etc.). The hypothesis (and it remains, to this day, a hypothesis, albeit one that has a lot of support) that prevailed was that bugs influence the immune system.

The dirty environment doesn't weaken the immune system. People with allergies and/or autoimmunity have as strong, if not stronger immune system. What sufferers lack is regulation. i.e., they have a hyper-responsiveness that is associated with "cleaner" living.

Now that I've got that bit out of the way, I'll go on the the actual question. The influence of environment on the immune system is strongest when you're young (explanation below). If you're over 15, the amount of dust in the air isn't going to make a lick of difference to your susceptibility to asthma, eczema, psoriasis, etc., regardless of whether it has a high dust mite load or not.

The studies you are referring to (the original ones, at least, nowadays there's so many reports of this that and the other it's hard to keep track) looked at the incidence of various immune disorders in migrants from one country to another. Individuals who have moved from a region with one risk level to a region with a higher or lower risk, they tend to adopt the risk of their new home. The cut off, however, seems to be around 15 years. Once you're an adult, your risk for these disorders is pretty much set.

In short, no.
posted by kisch mokusch at 10:13 PM on July 29, 2007 [1 favorite]

Nope. Those are just stories. The whole cleanilness and vaccinations leads to weaker children theory is really full of it. A couple hundred years of germ theory evidence should be more convincing than these claims. There's no shortage of outraged bloggers and alt-medicine types who make these claims but there's a real shortage of studies that suggest their claims might be true. The respectabe alt-medicine sites at least concede that the question is still very much in the air.

Cleanliness is actually good for you. Mother nature doesnt need your help in getting germs into you. The invisibble hand of evolution has taken care of this pretty well.

Secondly, a lot of these air ionizer products have been shown to be pretty ineffective. Essentially, theyre very cheap to make and are aggressively marketed because the margins are so high. See Sharper Image vs Consumer Reports. Best to stick to something with a HEPA filter.
posted by damn dirty ape at 10:18 PM on July 29, 2007

I've got kids who eat off the floor, or at least dirty tables; we don't let them wallow in muck, but we don't sweat the small stuff, either. They also share the house with two dogs.

They're two years old, and while they get colds and an occasional ear infection, that's about all they've gotten. Yet, since they were born, they've had a HEPA filter running in their bedroom at night -- because we already had it, and wanted something to generate white noise to help them sleep. The cleaning aspect wasn't really part of the decision.

FWIW, the filter has caught A LOT of stuff over the two years, it's a mess (we're having trouble locating a replacement filter, so now we're just running it with the fan when we bother to run it at all.) Anecdotally, then, the HEPA filter has kept the room cleaner, but our kids have not shown a predisposition to illness or allergy (in fact, in their first year of life they didn't get sick *once* because they were nannied during the day -- illnesses didn't start to come in at all until they started the bug-fest that is day care.)

So don't worry about it. Get a HEPA filter unit. Oh, and a HEPA vacuum is good as well, if you don't want to kick the dust right back out.
posted by davejay at 10:56 PM on July 29, 2007

ps -- they're twins, hence the plural references, not a mistake.
posted by davejay at 10:56 PM on July 29, 2007

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