BreathiIf you remember one number from this entire website, make it this one: forty to fifty per cent.
Here is what happens on either side of it.
Target 40–50% relative humidity indoors. Below 30% dries the airway lining and slows mucus clearance; above 60% encourages dust mites and mould growth.
Below 30%: too dry
The airway lining dries, the mucus layer thickens, and the cilia that move it work less efficiently. Throats feel scratchy, mornings feel tight, and nosebleeds become more common. Winter heating is the usual cause, and most homes with central heating sit here from November to March without anyone measuring it.
Above 60%: too damp
Dust mites thrive, mould finds surfaces to grow on, and both are genuine respiratory irritants. Bathrooms, kitchens and poorly ventilated bedrooms are the usual offenders. More humidity is not better — this is a target range, not a direction.
How to find out which you have
A digital hygrometer costs about $12 and is the highest-value purchase on this page. Put one in the bedroom, because that is where you spend eight uninterrupted hours breathing. Measure for a week before buying anything to fix it — you may find you have the opposite problem to the one you assumed.
Every package is one payment. No subscription, no card kept on file.
Order BreathiZenGetting to the range
- Too dry: a humidifier sized for the room, cleaned on schedule. Dirty tanks disperse what grows in them
- Too damp: ventilation first, extractor fans every time, then a dehumidifier if needed
- Either way: re-measure after two weeks rather than assuming the fix worked
And where our bottle sits in this: after the hygrometer. We compare the two directly and the humidifier wins for anyone with a genuine dry-air problem.
- Target 40–50% RH, measured not assumed
- Below 30%: dry lining, thickened mucus
- Above 60%: dust mites and mould
- Hygrometer first, appliance second
In one line. 40–50% relative humidity. A $12 hygrometer tells you which side you are on before you spend anything on the fix.