Most people spend most of their time indoors, especially those of us with indoor jobs. Between cooking, cleaning, pets, and everyday life, the air inside can fill up with more invisible particles than we realize. Air purifiers are built to freshen the spaces we live and breathe in, and make the air easier on our bodies.
I wanted to test the Alen BreatheSmart 25i because my wife and I both work from home and rarely open the windows to let the bad air out and good air in. Our spaces can start to feel heavy after a long day inside, and I was curious if a smart air purifier could actually make a difference.
I went into this experiment wondering if the BreatheSmart 25i would be something I’d actually want to keep long term or if it’d end up like my old purifier, which I keep around just because it’s all I have, even though I’m not sure it’s actually doing anything. I used it for several days and logged my experience below.
My Favorite Things
Simple and fast setup
Clear control labels
Quiet operation
Auto fan option
Responsive sensors
Useful mobile app
Key Features and Findings
Since unboxing it, I’ve been running the BreatheSmart 25i nonstop. It’s small and easy to move around. Setup took no time, and I barely noticed it in the room once it started running. With quiet fans, quick sensors, and real-time feedback in the app, this feels like an air purifier that’s actually paying attention. Here’s what stood out to me:
Setup: Getting the BreatheSmart 25i ready took basically no time. It weighs under 10 pounds, and the large handle on the back makes it easy to move anywhere I want. Most of the unit was wrapped in plastic that took just a minute to remove, and the filter was already in place, so all I really had to do after unwrapping the pieces was plug it in; it started filtering the air immediately.
The controls sit on top with a removable sticker that shows what each button does, so I never had to open the manual (and still haven’t, after over a week of using it). Wi-Fi is optional, but I connected to it so that I could use the app. It took a few tries to get connected, but then it was smooth sailing from there. Something I really appreciate about this air purifier is that the panel pops off magnetically, making it easier to reach the filter—my other air purifier unnecessarily complicates this process.
A magnetic cover makes filter replacements a cinch.
Lifewire / Jon Fisher
App and Controls: The BreatheSmart 25i automatically adjusts its fan speed, so I rarely need to use the app for remote control. Still, the Alen Air app works great! It connects instantly and shows real-time readings within seconds. It tracks PM, TVOC, and eCO2 levels, plus temperature and humidity, which I didn’t expect but really like. The dashboard shows the same color indicators as the device, so it’s easy to tell the air quality at a glance.
I also get alerts when something changes in the room, like when humidity spikes after a shower. The buttons on the purifier itself are simple and responsive, and everything feels very well thought out—there’s even a lock option to prevent yourself or kids from accidentally changing its settings. I really appreciate that the app logs history for every stat, tracks filter life, and lets me schedule power or fan changes. It makes the whole thing feel more useful day to day. My only wish is that the light controls were more effective; the Low option is still far too bright at night.
Monitor air quality and control the unit from anywhere with the Alen Air app.
Noise Level: This is easily the quietest air purifier I’ve ever used. It sits right next to my bed, and sometimes I have to hold my hand over the top just to check that it’s still on. The lowest fan speed runs around 20 dB, and the highest about 40 dB, but even at full power, it really doesn’t get distracting. I always leave it on auto mode so it can adjust itself based on air quality, and when it changes speed, there’s a smooth fade instead of an abrupt jump. I also keep other fans running at night, and I’ve never once heard the purifier over them.
Performance: I had never used a smart air purifier before trying the Alen BreatheSmart 25i, and it surprised me with how reactive it is. I keep it in a space that includes my bedroom and bathroom (about 300 square feet), and it responds fast to any change in the air. When I open a window or the bathroom fills with steam, the fan quickly speeds up, serving as a nice reminder that it really is paying attention.
I tested it by moving it into the kitchen after something burned in the oven, and within seconds, the app alerted me about a PM (particulate matter) jump while the fan picked up speed. I could then watch over the next 30 minutes as the BreatheSmart 25i cleaned the air. It also reacted to things like smoke and cleaning sprays, so it’s clear that the sensors are accurate, and it’s actually doing the work.
Monitor air quality over time with the History option.
Important Specs to Know
Dimensions
7.3″ D x 11″ W x 16.8″ H
Weight
8 lbs
Power
0.8-20W consumption; 6-foot, 9-inch cable
Coverage
Purifies 800 sq ft hourly, or 400 sq ft every 30m
Speed
4 settings with an automatic option
Filter Life
Essential: 9-12 months; Advanced: 6-8 months; Ultimate: 6-8 months
Filtration Rate
99.9% of airborne particles (up to 0.1 micron)
Basic monitoring and controls are available without the app.
Lifewire / Jon Fisher
The Bottom Line
This has been one of my favorite tech products to review. I find myself in the app almost every day to see what the air purifier has been up to.
The history charts and mobile alerts are easily my favorite parts. Paired with automatic fan speeds that make the device actually feel smart (those app screenshots say it all), I can forget it’s even running and still feel confident that the air is cleaner.
My biggest complaint is that one unit doesn’t cover more space in my house, though it is priced well for a single space like my bedroom. Alen also sells larger models and bundle discounts if you need to cover a larger area.
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