REVIEW – Many who live in Texas seem to suffer from allergies. Our family certainly does. Thus, I have been searching for air purifiers that might help us out. When the Alen BreatheSmart 35i Air Purifier came up for review, I wanted to see if it would clean our air to decrease our allergy symptoms. It seems sturdy and decently built, but it took much longer than I expected to clean the air after my candle smoke test.
⬇︎ Jump to summary (pros/cons)
Price: $269.00
Where to buy: Amazon
What is it?
The Alen BreatheSmart 35i Air Purifier is a device that filters and cleans your air of particulates (as small as 0.1 microns) using a high-efficiency particulate air (HEPA) filter.
What’s included?
- BreatheSmart 35i Air Purifier
- 35i True HEPA air filter (“Pure” air filter)
- Quick start guide
- User manual
- Power adapter
Tech specs
CADR – 190
CFM Speed – 1: 66 CFM|Speed 2: 98 CFM| Speed 3: 135 CFM| Turbo: 190 CFM
Coverage – Purifies up to 1,000 sq ft every hour or 500 sq ft every thirty minutes
Dimensions – H 20.6″ (52.32 cm) W 13″ (33.02 cm) D 7.6″ (19.30 cm)
Energy Star – Yes
Filter cost – $54 | Using “Pure” Air Filter
Filter life max – Pure: 9-12 months
Fresh/Odor filter life – 6-8 months
Filtration rate – Captures 99.9% of airborne particles as small as 0.1 micron.
Noise level – Lowest Speed – 29 dB | Highest Speed – 42 dB
Ozone – 0 PPM
Power consumption – 0.9 to 40 watts
Power supply – 24V, External Power Supply
Sensor – Automatic speed adjustment and coordinated to 5 color rings/ 4 speeds
Sound type – Pink Noise | All speeds
Speed settings – 4
Warranty – Forever Guarantee | with Product Registration & Active Air Filter Subscription
Weight – 11 lbs (5kg)
Design and features
The Alen BreatheSmart 35i Air Purifier is made of rigid white and gray plastic. It feels moderately well-made.
It has a touchscreen control panel containing the following (left to right):
- A filter status light indicates when to change the filter.
- A Lock button:
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- Hold for 3 seconds to lock/unlock the control panel.
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- A Light button:
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- There are three settings: low, high, and A (Auto).
- The Auto setting uses a light sensor to automatically adjust the control panel lights.
- If the light sensor detects a dark room, the control panel lights shut off.
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- The Power button:
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- The first tap turns on the air purifier.
- The second tap turns off the control panel lights (sleep mode).
- A third tap within five seconds of a previous tap will power off the purifier.
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- A Speed button:
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- There are four fan speeds: low, medium, high, and turbo.
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- An Auto button:
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- Tapping on the Auto button places the purifier in Auto mode, which adjusts the fan speeds according to what the sensor detects.
- The Auto button can also be used to connect the purifier to your WiFi. Press and hold this button for five seconds to start the WiFi connection process.
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- The WiFi indicator indicates WiFi connectivity.
The front panel of the air purifier is magnetically held in place. Before using the purifier for the first time, you need to remove this panel to remove the bag covering the HEPA filter.
To remove the filter, you need to rotate the filter lock counterclockwise.
The filter has arrows on the top indicating which direction to insert it into the air purifier.
The BreatheSmart 35i sent to me has the “Pure” filter, which is only one layer of HEPA filtration. If you want additional levels of filtration, there are other types of filters you can purchase to use in the purifier, but they cost more.
Here are the types of filters available:
- Pure filter – HEPA filter to filter allergens, dust, dander, pollen, mold, and microbes as small as 0.1 micron in diameter and lasts about 9-12 months ($54).
- Fresh filter – HEPA filter plus a carbon filter for protection from volatile organic compounds (VOCs) and lasts about 6-8 months ($64).
- Odor filter – HEPA filter, carbon filter, and an odor neutralizer for household odors like pet odor, diaper odor, and cooking odor, and lasts about 8 months ($69).
Here, you can see the air purifier’s fan.
The above shows the vent for the purified air.
There’s a one-inch gap between the front panel and the filter that functions as an air inlet.
Here’s the back of the purifier.
Both sides of the unit have sensors.
The bottom of the purifier has rubber pads to avoid scraping the floor.
The back of the purifier has a DC power port.
Assembly, Installation, Setup
I installed the Alen Air app to set up the BreatheSmart 35i Air Purifier. I followed the prompts and connected it to my WiFi (by holding the Auto button for five seconds).
Performance
Here’s the Alen BreatheSmart 35i Air Purifier set up in a 130 sq ft bedroom.
Once the purifier was set up and began functioning, it immediately detected “Fair” air quality. It took about 15 minutes to filter the air to an “Excellent” level.
One of the first things I noticed after powering up the purifier was how bright the light around the power button is (even when the light level is set on low). It’s a bit overwhelming and, in my opinion, unnecessary.
The color of this light surrounding the power button tells you at a glance the quality of the air:
- Blue: Excellent – Very low level of airborne particles detected.
- Green: Good – Low level of airborne particles detected.
- Orange: Fair – Medium level of airborne particles detected.
- Red: Poor – Significant level of airborne particles detected.
- Purple: Very Poor – Very significant level of airborne particles detected.
The above screenshots show the air quality data (first and second screenshots above) and the purifier’s control panel (third screenshot above) in the Alen Air app.
You can view the following air quality data (screenshots above from left to right) in the app:
- PM 2.5 (µg/m³) – Micrograms of particulates that are 2.5 microns in diameter per cubic meter of air.
- TVOC (ppb) – Total VOCs in parts per billion.
- eCO2 (ppm) – Equivalent carbon dioxide in parts per million. Instead of measuring the actual CO2, eCO2 is “derived from a total volatile organic components (TVOC) measurement.” (electronis360.c0m – this article has a great discussion on CO2 and eCO2 sensors).
- Temp (°F)
- Humidity (%)
The above video illustrates the basic functions of the air purifier and how it performed in my candle smoke test.
The above graphs show the results of the candle smoke test shown in the video. I was surprised to find that it took 18 minutes to filter the air of smoke. I reviewed other purifiers that took a fraction of that time (five minutes or less) to filter the air of candle smoke. I performed the test on the BreatheSmart 35i once in a hallway (which was open to the rest of my open-concept home), two times in a 130 sq. ft. bedroom with the door open, and twice in that same bedroom with the door closed, all with the same results: ~20 minutes to filter the air.
I can’t be sure why this occurred, especially since the Alen website says that the BreatheSmart 35i Air Purifier is “[d]esigned to purify rooms up to 1,000 sq ft once per hour, or 500 sq. ft. every 30 minutes”.
Does it mean that this purifier doesn’t perform as well as the others I’ve tested? Are the sensors different? Are the quality of the sensors different? How frequently do the sensors sample the air to collect data? Perhaps there are differences in the fans (power, size, etc.), the quality of HEPA filters, or a combination of all of the above. That’s a lot of factors to figure out. As an average air-purifier consumer, I don’t have a lab to do further testing; thus, it makes me wonder about the quality of all air purifiers and their efficacy. I guess I question the efficacy of the BreatheSmart 35i more than the others I’ve tested, since Alen specifically stated that the purifier filters 1000 sq ft per hour, and yet it took nearly 20 minutes to filter the air in a 130 sq ft (1300 cu ft) room.
Final thoughts
The Alen BreatheSmart 35i Air Purifier seems like a decently-made device. However, I was disappointed in how it performed in my candle smoke test. It took 18 minutes to filter the air of smoke, and subsequent tests replicated those results even when placed in a relatively small enclosed bedroom (130 sq. ft.). My other air purifiers filtered the air in five minutes or less. Additionally, my unit only came with a HEPA filter when other purifiers come with a HEPA filter, a carbon filter, and prefilters that filter out large particles to preserve the life of the HEPA filter.
What I like about the Alen BreatheSmart 35i Air Purifier
- It’s quiet.
- The Auto light setting uses a light sensor to detect a dark room and turns off the control panel lights (thank goodness – that light is BRIGHT!).
- The Auto mode automatically adjusts the fan speeds according to what the sensor detects.
What needs to be improved?
- It’s very slow to detect candle smoke (~30 seconds).
- It’s very slow to filter the air of candle smoke (~20 minutes).
- The air quality light is overwhelmingly bright.
- Replacement filters are expensive ($54 – $69), and there are three types to choose from (Pure, Fresh, and Odor).
- The Pure filter is only a HEPA filter that provides one layer of filtration; there are other purifiers that have prefilters that filter out large particles like dust to help prolong the life of the expensive HEPA filter.
- Other purifiers’ filters include a carbon filter to absorb odors and VOCs.
Price: $269.00
Where to buy: Amazon
Source: The sample of this product was provided for free by Alen. Alen did not have a final say on the review and did not preview the review before it was published.
Check out these other air purifier reviews!
- Rabbit Air Minus A2 Air Purifier review – another great air purifier from Rabbit Air
- Levoit EverestAir Smart Air Purifier review – a great air purifier for extra-large rooms in open-concept homes
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$34.90 (as of September 2, 2025 02:32 GMT -04:00 - More infoProduct prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on [relevant Amazon Site(s), as applicable] at the time of purchase will apply to the purchase of this product.)
