· by Michael Blair, Nashville's Cleaning Service
Indoor allergens in Middle Tennessee come down to two things: what comes in from outside, and what gets stirred back into the air while the house is being cleaned. Several standard cleaning habits do more stirring than removing, and a couple of the most useful steps have nothing to do with a cloth or a vacuum.
What cleaning habits make allergies worse?
Dry dusting lifts particles into the air rather than picking them up. NIEHS’s page on dust mites and cockroaches puts it plainly: use a damp mop or rag to remove dust, and never a dry cloth, because a dry one stirs up allergens.
The vacuum can do the same thing. NIEHS recommends a HEPA filter or a double-layered microfilter bag, and when a 1999 study in the Journal of Allergy and Clinical Immunology tested vacuums and bags sold to allergic households, single-layer bags let far more cat allergen through than most two- and three-layer microfiltration bags, and even the better machines still leaked some. That leakage may be part of why a room can feel worse right after it is vacuumed, and NIEHS suggests staying out of a freshly vacuumed area for 20 minutes while the dust settles.
What cleaning actually helps with allergies?
Damp dusting from the top of the room down, HEPA or double-layer-bag vacuuming, and bedding washed every week. NIEHS gives the temperature for the wash, 130 to 140 degrees Fahrenheit, hot enough to kill dust mites, and adds dust-proof covers for the mattress and pillows and a night in the freezer for bedding that can’t be washed. Dusting and vacuuming are on the written checklist for our recurring cleaning, and the EPA’s asthma triggers page gives a reason to be out while we do it: people with asthma or allergies should leave the area being vacuumed.
Shutting the windows on high pollen days is unpopular in a Tennessee spring, and it is still on the same EPA page: stay inside with the windows closed on high pollen days and when pollutants are high. Pet dander adds its own layer, which our post on cleaning a house with pets takes up.
- Damp cloth or rag, never dry dusting
- HEPA filter or double-layer bag in the vacuum, then 20 minutes out of the room
- Bedding washed weekly at 130 to 140 degrees
- HVAC filter checked monthly in pollen season, changed when it looks loaded
- Windows closed on high pollen days
The filter is a big lever
The furnace filter works on the air the system moves every time it runs, so we count it as part of allergy cleaning rather than a separate chore. For the rating, the EPA’s guide to air cleaners in the home sets the floor at MERV 13, or the highest number your system can handle. Most furnaces cope with a MERV 13 without equipment trouble, by the EPA’s account, so long as it gets changed often.
The same guide says manufacturers typically recommend replacement every 60 to 90 days, and sooner if filters look heavily soiled when they come out. Through pollen season we would check it monthly and change it when it looks loaded. Check the fit while it is out, too: the EPA wants it snug enough that air does not leak around the edges, without bending or crushing it to make it go in.
Humidity and dust mites
Humidity decides how well dust mites do. Arlian and colleagues’ 1999 study on reducing relative humidity to control dust mites calls indoor relative humidity the key factor in their survival, and found that keeping the daily average below 50 percent restricted their growth even when cooking or bathing pushed it above 50 for two to eight hours a day.
NIEHS sets the target at or below 50 percent and names a dehumidifier or air conditioner as the way to hold it there. The EPA’s brief guide to mold, moisture and your home asks for below 60 percent, ideally between 30 and 50, and a damp bathroom is the same problem in another form, covered in our post on mold and mildew in a Nashville bathroom. NIEHS is also frank that no home, however clean, is ever completely free of dust mites, so the humidity, the covers and the hot wash carry part of the load alongside the cleaning. If you would rather someone else kept up the dusting and vacuuming through pollen season, ask us for a free estimate.
Sources
- NIEHS (NIH), Dust Mites and Cockroaches (reviewed 2026) — Damp mop or rag, never a dry cloth; HEPA filter or double-layered microfilter bag; 20 minutes out of the vacuumed area; bedding washed weekly at 130 to 140 F; dust-proof covers; freeze non-washable bedding; humidity at or below 50 percent; mites cannot be completely eliminated
- U.S. EPA, Asthma Triggers: Gain Control — People with asthma or allergies should leave the area being vacuumed; windows closed on high pollen days
- U.S. EPA, Guide to Air Cleaners in the Home — At least MERV 13 or as high as the system allows; replacement typically every 60 to 90 days, sooner if heavily soiled; filter must fit snugly so air does not leak around it
- U.S. EPA, A Brief Guide to Mold, Moisture and Your Home — Indoor humidity below 60 percent, ideally 30 to 50 percent
- Arlian, Neal and Vyszenski-Moher, J Allergy Clin Immunol (1999), Reducing relative humidity to control the house dust mite — Relative humidity is the key factor in mite survival; a mean daily RH below 50 percent restricts population growth even with 2 to 8 hours a day above 50
- Vaughan, Woodfolk and Platts-Mills, J Allergy Clin Immunol (1999), Assessment of vacuum cleaners and vacuum cleaner bags recommended for allergic subjects — Single-layer bags leaked far more allergen than most multi-layer microfiltration bags; allergy vacuums still leaked some allergen
FAQ
Cleaning for Middle Tennessee Allergy Season — questions
Does vacuuming make allergies worse?
It can stir allergens up for a while. NIEHS recommends a HEPA filter or a double-layered microfilter bag in the vacuum, and staying out of the vacuumed area for 20 minutes afterward so the dust can settle. Lab testing of vacuums and bags sold for allergic households found that single-layer bags let much more allergen through, and that even the better machines still leaked some.
How often should I change my filter in pollen season?
The EPA says manufacturers typically recommend replacement every 60 to 90 days, and more often if the filter looks heavily soiled when you take it out. Through pollen season we suggest checking it monthly and changing it when it looks loaded. While it is out, make sure it fits snugly so air cannot leak around the edges, and use one rated MERV 13 or higher if your system allows.
What indoor humidity reduces dust mites?
At or below 50 percent, which is the NIEHS target, held there with an air conditioner or a dehumidifier. A 1999 study found that keeping the daily average under 50 percent restricted mite growth even when humidity rose above that for two to eight hours a day. The EPA, writing about mold, asks for below 60 percent and ideally between 30 and 50.
How do you clean a house when you have a dust allergy?
Take the dust out instead of moving it around: wipe from the top of the room down with a damp cloth, never a dry duster, and vacuum with a HEPA filter or a double-layer bag. Stay out of the room for 20 minutes afterward, wash bedding weekly in hot water, and cover the mattress and pillows.