In our head to head comparison today, we will be looking at two of the best air purifiers for large rooms. The Airmega AP-2015E(G) 400S by Coway and the BreatheSmart 75i by Alen are high-end air purifiers that feature aesthetic designs and high performance to keep our air as healthy as possible.

Airmega 400S vs. Alen BreatheSmart 75i

Airmega 400S

Although they are quite expensive, the two units are among the most advanced air purifiers with state of the art smart technology that makes them operate automatically, without any human intervention.

Here is a head to head comparison between the Airmega 400S and Alen BreatheSmart 75i.

Air Quality Monitoring

The Airmega 400S and the BreatheSmart 75i have pollution sensors that closely monitor the quality of the air in the room. They have colored LED lights that keep you in touch with the level of pollution. This monitoring process is automatic and continuous all day and night and only stops when the two units are switched off.


The Airmega 400S has three modes that it automatically adjusts to depending on the air conditions of the room. The first mode is Auto, which automatically adjusts fan and filtration speeds to meet the necessary cleaning requirements in the room. The Eco mode preserves energy and will turn off the fan for 10 minutes when the quality of air is good.

The Sleep mode has light sensors that detect when the room is dark. This mode allows it to switch to a quiet setting to allow you to sleep in peace. Also, the 400S has a programmable timer that allows you to set the duration of the purifying process.

Alen BreatheSmart 75i vs. Airmega 400S

Alen 75i

The Alen 75i has two operational modes, manual and auto. It also features four fan speeds: low, high, medium and turbo that go hand-in-hand with the two modes. In auto mode, the unit responds to the pollution levels in the room and automatically switches to either of the four modes. For instance, when the air has high pollution, it will switch to turbo speed, as it is faster and takes in a high amount of air.

The 75i is also programmable under the manual mode. You can set the timer to run for a specific duration and to start at a specified time. In addition, the 75i generates a soothing pink noise that facilitates a better sleeping experience.


Both units are relatively quiet in comparison to other air purifiers. The BreatheSmart 75i has a built in WhisperMax technology, which purifies large amounts of air with very little noise. The noise levels increase with fan speed, and the turbo mode is the loudest. The Airmega 400S is also very quiet in the lowest setting and reasonably loud in the highest mode.

Airmega 400S

Airmega 400S

Filtration process

There is a slight difference between the two filtration processes. The Airmega 400S features a dual filter system made up of the pre-filter and the Max2 filter. The pre-filter is constructed with a micromesh and helps get rid of hair, fur, and large dust particles.

The Max2 filter is a true HEPA filter and captures tiny particulates up to the size of 0.3 microns from the air. In addition, the filter is also constructed with activated carbon that reduces volatile organic compounds and toxic fumes like NH3 (ammonia) and CH3CHO (ethanol).

The Airmega also features a filter indicator that alerts you when to clean the pre-filter and also when to replace the Max2 filters. It has a maximum cleaning coverage of up to 1560 square feet and cleans the entire space after every 30 minutes.

Alen BreatheSmart 75i

Alen 75i

The Alen BreatheSmart also has a dual filter system, comprising the washable pre-filter that captures large particulates and the electrostatically charged HEPA filter system that captures more than 99% of tiny pollutants. It also includes an antimicrobial layer that inhibits the growth of bacteria and fungi and is packed with activated carbon to get rid of smoke, bad odors and harmful chemicals.

Another unique feature of the 75i is the ozone ionizer that charges the particulates in the air allowing them to fuse together for easy capture. It also has a filter life timer that informs you when to replace the HEPA filter. The BreatheSmart 75i has a maximum coverage of 1300 square feet and automatically cleans after every 30 minutes.

Airmega 400S Air Purifier

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Coway Airmega 400S vs. Alen BreatheSmart 75i

Smart Technology

The major difference between the two is that the Airmega can be operated remotely with a mobile app, while the BreatheSmart 75i cannot. The Airmega is Wi-Fi enabled and is operated by the Coway IoCare mobile app, which allows you to schedule, monitor and check out notifications from the unit. It further works with Amazon Alexa, which means it is receptive to vocal commands.

Both units are excellent at keeping air purified in large rooms. However, the Airmega 400S has a slight edge over the Alen BreatheSmart 75i because it can be operated with a mobile app and is also responsive to vocal commands. However, you can never go wrong with either choice, as they both get our seal of approval.

Alen BreatheSmart 75i Air Purifier

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