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Alen Breathesmart 45i Review: 11 Real World Tests

Derek Hales

Written By: Derek Hales

Updated on:

Alen Breathesmart 45i
96 Purification
97 Build Quality
100 Noise
96 Usability
98 Maintenance
96.5 Overall Score
Tested With Scoring System 1.1

Best For

  • Perfect for medium to large-sized rooms with 800 sq. ft. coverage
  • On its lowest power setting, it produces very low noise.
  • Exceptional price point compared to other purifiers with similar coverage


  • Lack WiFi capabilities, but has a slightly more expensive version with that functionality

Our Verdict

The Alen Breathesmart 45i is an excellent mid-sized air purifier for any medium to large-sized room with its 800 sq. ft. coverage. Its powerful filters were able to achieve excellent performance in reducing both PM2.5 & PM10 to 0.1 ppm at the end of our testing. Additionally, the noise levels on the max fan speed of the 45i are some of the lowest decibels we have tested to date. Overall, this is an outstanding air purifier for both performance and usability.

However, one downside to this specific model we tested was the app connectivity. For such an exceptional system, it lacks the modern functionality of a WiFi-connected app for remote control. That said, there is an upgraded version of the 45i with WiFi capabilities that costs a little extra.

Filter Type: HEPA, Carbon, PreFilter
Coverage Area: 800 sq. ft.

In This Review
Purification Performance | Ozone Test | Filters | Coverage | Build Quality | Noise Test | Usability | Maintenance | Size | Specs | Product Evolution | Comparison | FAQs

Performance Summary

At Modern Castle we test 11 different factors that impact the performance, build quality, and usability of the air purifier. Below is a complete list of our testing categories and their performance.

Test TypeTest Data
PM2.5 (1 hour test)0.2 ppm
PM10 (1 hour test)0.2 ppm
Particles (2 hour test)43
AQI (2 hour test)2
Ozone Detected0.0 ppm
Filter TypeHEPA, Carbon, Pre-Filter, Ionizer
Coverage Area800 sq. ft. (74 sq. m.)
Max Wind Speed8.7 mph (14.0 kph)
Noise Test53.4 dB

Purification Performance

To test the purification performance of the Alen Breathesmart 45i, we placed it in a medium sized room in our office (~14’ x 10`). Next, we lit incense to introduce smoke and other particulates into the air for 30 seconds. After, we use a professional air quality detector to take a measurement of the smoke-filled air.

Air Quality Testing Meter
Electronic testing meter we use to measure particulates and air quality

Next, we run the air purifier on the highest fan speed for 2 hours, taking measurements of the air quality at the one hour mark and the end of the test. Here is what we found:

Performance MetricStarting MeasurementAfter 1 HourAfter 2 Hours
PM2.538.6 ppm0.2 ppm0.1 ppm
PM1066.5 ppm0.2 ppm0.1 ppm

In our air purification tests, the Alen Breathesmart 45i was able to reduce PM2.5 to 0.2 ppm. This is 0.28 ppm lower than the average of 0.48 ppm, based on all of our air purification tests to date.

Alen Breathesmart 45i
Alen Breathesmart 45i

Below, we’ve included information on the testing criteria and what defines good vs. bad air quality. Simply, the lower the numbers the better.

Air Quality Pm 25 Index

Alen does mention in their quick start guide that after the initial start-up, they recommend placing the fan speed on “Turbo” for 2 hours to help purify the surrounding air. At our second-hour measurement, we saw the PM2.5 further decrease to 0.1 ppm, which is near our testing average of 0.15 ppm. After that, they recommend placing the Alen Breathesmart 45i on “Auto Mode” to adjust the fan speed as needed.

Ozone Test

With most air purifiers ozone generation isn’t an issue. That said, some that use negative ion generators have the potential to create ozone. To test this, we run the Alen Breathesmart 45i, letting it run for 1 hour and measure the levels of ozone before and after with an ozone meter device.

Pre-test Ozone

0.0 ppm

Post-test Ozone

0.0 ppm

In our ozone tests, the Alen Breathesmart 45i generated 0.0 ppm.



The Alen Breathesmart 45i has a 3-in-1 air filter.

Alen Breathesmart 45i Filter

Pre-Filter – Pre-filters are designed to catch larger particulates and debris before it makes its way to the primary filters. This can include hair, lint, and more.

Alen Breathesmart 45i Carbon Filter

Carbon Filter – Carbon filters are able to remove smells, odors, and VOCs (volatile organic compounds).

Alen Breathesmart 45i HEPA Filter

HEPA Filter – The HEPA filter is the primary filtration layer. It removes ultra small particulates including dust, pollen, mold, and more.

Alen Breathesmart 45i Ionizer

Ionizer – Ionizers and similar technology release charged particles into the air. These particles clump with other airborne particulates, causing them to fall to the ground and cease to be airborne. This feature can be turned on / off.


The Alen Breathesmart 45i has a coverage area of 800 sq. ft. It is best suited for medium to large rooms or even a 1 to 2-bedroom apartment.

Coverage Area

800 sq. ft.


245 CFM

Comparing the Alen Breathesmart 45i to the average, we see it is slightly larger, but the CADR is slightly smaller. Across all air purifiers we’ve tested to date, the average coverage area is 744 sq. ft. and the average CADR is 290 CFM.

Wind Speed Test

Our wind speed test uses an anemometer placed directly on the air vents of the Alen Breathesmart 45i to measure the fan speeds in miles per hour. We run it on the lowest and highest fan speeds and record the speed of the air coming out of the device.

Minimum Wind Speed

2.5 mph

Maximum Wind Speed

8.7 mph

In our wind speed test, the Alen Breathesmart 45i was able to generate a maximum wind speed of 8.7 mph. This is 3.6 mph lower than the average of 12.3 mph, based on all of our wind speed tests to date.

We typically see air purifiers with larger coverage produce higher wind speed. However, with the Alen Breathesmart 45i, it did come in slightly slower wind speed.


Build Quality Test

Our build quality test is a subjective test where we examine and assess the major material and design components of the air purifier. Specifically, we are looking for build and design issues that are more likely to break and/or be difficult to use.

Alen Breathesmart 45i
Alen Breathesmart 45i

The Alen Breathesmart 45i has an exceptional build quality between the body, fan, and filters. Each coming together to make a remarkable air purification system in quality. The body is constructed of durable plastic and has a heavy base to prevent possible tipping. The fan is placed in the rear of the system. Finally, the filters are 3-in-1, combined for simplicity in handling and maintenance.

PartBuild Quality

When compared to others in similar size and coverage, The Alen Breathsmart 45i stands out with its overall body construction and handling. It had convenient handles for moving the system around. The filter cover was easy to remove and securely snap back in place. It gave me confidence that it wouldn’t easily tip over if bumped. Overall, the build quality is excellent and exactly what we look for in a mid-sized air purification system.

Alen Breathesmart 45i Plastic Packaging
Alen Breathesmart 45i Plastic Packaging

Additionally, the Alen Breathesmart 45i comes with the option to change the color of the body panels. The options are White, Oak, Weathered Gray, Brushed Stainless, Graphite, and Espresso.


Noise Test

To determine the level of noise that the Alen Breathesmart 45i creates we use a sound meter and measure the decibel levels on both the lowest and highest fan speeds. In addition, we measure the ambient noise levels of the room as a baseline comparison.

Ambient Noise

41.2 dB

Min Noise

41.3 dB

Max Noise

53.4 dB

In our noise tests, the Alen Breathesmart 45i generated 53.4 dB of noise on the max fan speed. This is 8.6 dB lower than the average of 62.0 dB, based on all of our noise tests to date.

The Alen Breathesmart came in with an excellent score for its max noise. Our ambient noise in the lab was 41.2 dB, which means that the noise from the Breathesmart 45i was not overpowering. It was a comfortable level of white noise while on its max fan speed.



The Alen Breathesmart 45i has a friendly user functionality with its simplistic controls.



Removing the Alen Breathesmart 45i from its packaging took no more than 5 minutes, with the most tedious task being removing all the plastic covers.

Alen Breathesmart 45i Plastic Unboxed
Alen Breathesmart 45i Plastic Unboxed

There are plastic wraps across the body, across the control panel, and the filter comes wrapped in plastic. Be sure to remove all the plastic before turning the system on.


Controls & Display

The control panel is simple and has LED lights to help the user identify the current setting and status of the Breathesmart 45i. However, I do wish Alen had labeled the “T” with the full word “Turbo” on the control panel. It took me a few minutes to find it in the manual on what exactly the “T” fan speed is.

Alen Breathesmart 45i Controls
Alen Breathesmart 45i Controls

Wireless Controls

There are no wireless controls with this base model. For wireless control, you will need to upgrade to the Air Intelligence Bundle

In The Box

Alen Breathesmart 45i Unboxed
Alen Breathesmart 45i Unboxed


The Alen Breathesmart 45i has an estimated yearly maintenance cost of $69. The following are the major maintenance tasks for the Alen Breathesmart 45i.

TaskDescriptionEst. Annual Cost
HEPA, Carbon, Pre FilterReplace Every 12 Months$69.00
SensorRemove any obstructions, clean as needed$0

Size & Dimensions

Many of the air purifiers we test come in a symmetrical shape, like a circle or square. However, the Alen Breathesmart 45i has a wide front face of 15 inches, giving it a wide body look when viewed from the front. But, when looking at the thickness and depth, it only measures 8.5 inches.

Height25.0″ (63.5 cm)
Length8.5″ (21.6 cm)
Width15.0″ (38.1 cm)
Weight15.0 lbs. (6.8 kg)


The following table details the product specifications according to the manufacturer.

Manufacturer Specifications
ModelBreathesmart 45i
Height25.0″ (63.5 cm)
Length8.5″ (21.6 cm)
Width15.0″ (38.1 cm)
Weight15.0 lbs. (6.8 kg)
FilterHEPA, Carbon, Pre-Filter, Ionizer
Noise Levels53 dB (max)
Coverage Area800 sq. ft.
Wi-Fi CompatibleNo
PriceCheck Price

Product Evolution

The Alen Breathesmart series has several models of this series that range in size and coverage. The largest is the Alen Breathesmart 75i covering 1,300 sq. ft., the 45i is the mid-range air purifier, and the Alen BreathSmart FLEX comes in with a slightly smaller coverage than the 45i with 700 sq. ft.

Alen Breathesmart 45i
Alen Breathesmart 45i

Each model in the series comes with a WiFi-connected option, allowing users to connect their air purifier to the Alen Air App. This gives the user additional functionality and control over their air purifier.

How does Alen Breathesmart 45i compare?

Below is a complete list of our air purifier tests and critical product data compared side by side to the average based on all of our air purifier tests to date.

Test TypeTest DataAvg. Data
PM2.5 (1 hours)0.2 ppm0.4 ppm
PM10 (1 hours)0.2 ppm0.7 ppm
Particles (1 hours)4360.8
AQI (1 hours)21
Ozone Detected0.0 ppm0.0 ppm
Filter TypesHEPA, Carbon, Pre-Filter, Ionizern/a
Coverage Area800 sq. ft.744 sq. ft.
Max Wind Speed8.7 mph12.3 mph
Noise Test53.4 dB62.0 dB

While the Alen Breathesmart 45i had impressive results in air purification, it did struggle to achieve those results within the first hour. Typically, we see exceptional air purifiers achieve 0.1 PPM in both PM2.5 & PM10 within the first hour. However, it achieved those scores in our 2nd-hour measurement. It’s an excellent air purifier, but for complete purification, you’ll need to wait a couple of hours, depending on the size of your room.

Other Air Purifiers to Consider

Airdoctor 3500i Floor Sideview

AirDoctor 3500i

The AirDoctor 3500i is the latest model from AirDoctor that offers app connectivity for enhanced user remote functionality.

This air purifier would be best for remote user functionality and has a slightly larger coverage area than the Alen Breathesmart 45i.

Alen Breathesmart 75i

Alen Breathesmart 75i

The Alen Breathesmart 75i is a medium-sized air purifier that can cover up to 1,300 sq. ft.

If you’re specifically looking to stay within the Alen Breathesmart brand, the 75i is an exceptional upgrade from the 45i. Additionally, it comes with a Wi-Fi model so you can connect all your Breathesmart systems together.

AirDoctor 3000

AirDoctor 3000

The AirDoctor 3000 is a medium-sized air purifier from AirDoctor that has exceptional purification performance

If you’re not concerned about Wi-Fi connectivity, the AirDoctor 3000 is the perfect alternative for its performance.


Should I run the air purifier all the time?

Yes, the Alen Breathesmart 45i comes with a convenient “Auto Mode” that will allow you to turn the system on, and it will automatically adjust the fan power based on current air quality.

Does the Alen Breathesmart 45i have an Ionizer?

Yes, it comes with an ionizer that you can toggle on and off.

Does the Alen BreathSmart 45i have WiFi app connectivity?

This particular model we tested does not have WiFi, however, you can upgrade to the Air Intelligence Bundle which includes a WiFi-connected model.

About Derek Hales

Derek HalesDerek Hales is the Founder and Editor-in-Chief of He has been featured in Fast Company, Reader's Digest, Business Insider,, She Knows, and other major publications. Derek has a Bachelor's Degree in Business Administration from Kansas State University. Hales has been testing and reviewing products for the home since 2014.