Value Village ／ Health
This answer is a draft. It stays unpublished until legal review and source verification are complete.
It is not pollen season, yet you sneeze when you get home and wake with a blocked nose. In Japan, the second most common cause of allergic rhinitis after pollen is "house dust", and most of that is the droppings and dead bodies of house dust mites (hyōhi-dani). Before you buy an air purifier, here is the order in which the measures work.
| Priority | Measure | Details | Effect |
|---|---|---|---|
| 1 | Bedding | Vacuum futons, mattresses and pillows at least once a week (20 seconds per m², slowly). Wash sheets and covers weekly (at 55°C (131°F) or above the mites die too; an ordinary wash still rinses away the allergen). Anti-mite covers (a high-density weave that mites cannot pass) | Large |
| 2 | Floors | Remove carpets and rugs, or switch to washable ones. Wipe tatami and wooden floors (vacuuming alone stirs dust up). Use a vacuum with a HEPA filter and weak exhaust | Large |
| 3 | Humidity | Indoor humidity 50–60% or below (mites multiply most at 60–80% and 20–30°C). Dehumidifier, ventilation, the air-conditioner's dry mode. Closets and oshiire (built-in futon cupboards) too | Medium to large |
| 4 | Fewer fabrics | Fabric sofa → leather or synthetic leather, only soft toys that can be washed (wash and tumble-dry, or bag them and freeze for a day → wash), heavy curtains → washable ones | Medium |
| 5 | Air purifier | Reduces airborne allergen. Guide: HEPA filter, rated floor area twice the size of the room | Small to medium (not enough on its own) |
| 6 | Mite traps and anti-mite sprays | Supplementary. Reduce live mites, but not the allergen (droppings and bodies) | Small |
[Verify] Check the breeding conditions for mites, mite numbers in bedding, and the start year and minimum age for health-insurance coverage of sublingual immunotherapy against Japanese Society of Allergology and MHLW materials.
Most allergen has settled on floors and bedding; an air purifier alone has limited effect. Bedding and floors come first.
The inside rarely reaches 50°C, and even when mites die, the droppings and bodies remain as allergen. Vacuum after airing; wash the covers.
Fewer live mites, but the allergen (droppings and bodies) remains. Removing and washing is the core.
Sublingual immunotherapy (covered by health insurance) aims to change the underlying reaction. It takes 3–5 years, but many people find their symptoms much milder.
The exhaust stirs dust up, so wipe first, vacuum slowly, and pair it with ventilation and a mask. Method matters more than frequency.
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https://www.jsaweb.jp/
https://allergyportal.jp/
https://www.tmiph.metro.tokyo.lg.jp/
⚠️ Editorial note: the source URLs above were identified by search. Our working environment cannot reach go.jp domains, so the contents have not been checked against the text. Verify every source before publication and record who checked it and when.
What we share here are ideas and everyday practices passed down among people living in Japan, together with general information drawn from public sources. They are not official recommendations, and they are not professional instruction. Practices vary between households and regions.
This is general information. Results vary from person to person and depend on your own conditions and surroundings.
Please decide for yourself, using your own judgement, whether any of this suits your situation. We cannot accept responsibility for any damage, loss or injury arising from following this article.
This article is not meant to diagnose or manage any specific medical condition. If you are worried about your health, see a doctor rather than relying on your own judgement.
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