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So there I was, staring at my Temtop M10 showing lovely low PM2.5 numbers - everything looked perfect on paper. But I felt absolutely terrible. Stuffy nose, headache, that gross sticky feeling you get in summer. Something wasn’t adding up.

Turns out I’d been measuring half the story.

The Problem Nobody Talks About

Air quality monitors - even good ones - tell you about pollution. PM2.5, VOCs, formaldehyde, that sort of thing. Brilliant for knowing if your cooking’s set off the smoke alarm or if your new sofa is off-gassing nasty chemicals.

But they don’t tell you jack about humidity.

And humidity? That’s the thing that makes your flat feel like a swamp in August or a desert in January, even when the actual air quality is spot-on.

The Morning I Finally Got It

October 2024. I woke up with a blocked nose for the third morning running. My Temtop M10 was sitting there on the bedside table showing 12 µg/m³ PM2.5 - well within the “good” range. VOCs were fine. Temperature was fine. What was going on?

Out of frustration, I ordered an affordable hygrometer on Amazon - a ThermoPro TP50. Stuck it next to my air quality monitor.

Next morning: 73% humidity.

No wonder I felt like I was breathing through a wet flannel.

Why Humidity Matters (The Stuff They Don’t Tell You)

Here’s what I’ve learned over the past year of tracking both:

When It’s Too Humid (Above 60%)

Dust mites love it. They absolutely thrive in humid conditions. And their droppings? That shows up as PM2.5 on your monitor eventually, but by then you’ve been breathing it in for weeks.

Mold grows faster. Not the obvious black mold you can see - I’m talking about the microscopic stuff that lives in your curtains, behind furniture, in the seal of your washing machine. It’s constantly releasing spores into the air.

I ran a test in my bathroom (naturally humid after showers). Left my Temtop M10 in there for 24 hours with humidity at 75%. PM2.5 readings crept up from 8 to 23 µg/m³ over the day, even though I hadn’t done anything. That’s mold spores and dust mite particles building up.

When It’s Too Dry (Below 30%)

Your lungs get irritated. Dry air strips moisture from your respiratory system. Makes you more sensitive to any particles that are in the air. I tested this in January 2025 when my heating was on full blast - humidity dropped to 28%, and suddenly even 10 µg/m³ PM2.5 (normally fine) felt uncomfortable.

Static electricity everywhere. Not health-related, but bloody annoying. Everything you touch gives you a shock.

The Sweet Spot (40-50%)

This is where I feel best. Air quality monitor showing good numbers and humidity in the right range. No stuffiness, no dry throat, just normal breathing.

My Current Setup (Two Devices)

I use:

1. Temtop M10 - Tracks PM2.5, VOCs, formaldehyde. The actual pollution stuff.
2. ThermoPro TP50 - Tracks humidity and temperature. Affordable, does the job.

The Temtop sits in my bedroom (where I spend 8 hours a night). The hygrometer moves around - bathroom after showers, kitchen when cooking, living room when I’m working.

Between the two, I get the full picture.

What I Actually Do With This Information

When humidity goes above 60%:

• Open windows (even in winter - just for 10 minutes)
• Run dehumidifier in bathroom after showers
• Check behind furniture for damp patches
• Wash bedding more often (dust mites)

When humidity drops below 35%:

• Turn heating down a notch
• Dry laundry indoors (adds moisture to air)
• Leave bathroom door open after showers to spread humidity around

When both readings are good:

• Nothing. Just carry on. That’s the goal.

The Cheaper Option (If Buying Today)

Right, honesty time: if I was buying from scratch today, I wouldn’t get two separate devices.

I’d get an all-in-one monitor that tracks both pollution and humidity. Something like:

Amazon Smart Air Quality Monitor - Does PM2.5, VOC, CO, temperature, and humidity. Connects to Alexa. I tested one at a mate’s flat in August 2025 - worked brilliantly. Voice alerts when humidity got too high, graphs in the app showing everything.

These cost more than a basic hygrometer (obviously), but less than buying an air quality monitor and a separate hygrometer. And you only need one device cluttering up your flat.

But Why Not Just Buy The All-In-One?

Valid question. Here’s my thinking:

If you already own an air quality monitor (like I did): Just add an affordable hygrometer. Simple addition, job done. No point buying a whole new device.

If you’re starting from scratch: Get an all-in-one. Simpler, less hassle, one app instead of reading two devices.

If you want the best data: Separate devices. My Temtop M10 is brilliant for air quality - very responsive, updates fast. The all-in-ones I’ve tested are good, but not quite as quick to react. For humidity though? Doesn’t matter. It changes slowly anyway.

Real Example: Last Week

Wednesday night. Temtop M10 showing 15 µg/m³ PM2.5 (fine). But I felt rough - headache, couldn’t concentrate on work.

Checked the hygrometer: 67% humidity.

Opened the bedroom window for 15 minutes. Humidity dropped to 52%. Felt immediately better. PM2.5 actually went up slightly (outdoor air coming in), but I felt loads better because the humidity was sorted.

That’s the thing - sometimes humidity matters more than a few extra micrograms of PM2.5.

What About Winter?

Different problem. Heating dries everything out.

January 2025, my flat hit 26% humidity with the radiators on. My throat was scratchy, nose felt dry, even though air quality readings were perfect (PM2.5 around 8 µg/m³).

Solution: dried laundry indoors, left bathroom door open after showers, put bowls of water on radiators (old-school but it works). Got humidity back up to 42%. Much better.

The Bottom Line

Air quality monitors are brilliant. I wouldn’t be without mine. But they’re only half the story.

Humidity affects how your body responds to whatever’s in the air. Too high and you’re breeding mold and dust mites. Too low and your lungs get irritated.

My advice:

• If you already have an air quality monitor: add a basic hygrometer. See what your humidity actually is.
• If you’re buying from scratch: get an all-in-one that does both.
• Ideal range: 40-50% humidity, PM2.5 below 25 µg/m³.

That’s when I feel best, and that’s what I aim for.

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Links:

• ThermoPro TP50 Hygrometer on Amazon UK - Budget option if you already have an air quality monitor
• Check Amazon Smart Air Quality Monitor on Amazon UK - Best all-in-one option
• Check Temtop M10 on Amazon UK - If you want separate devices for best data

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