Levoit Core 300S, with over 94,000 reviews on Amazon, ranks as the No.1 best-seller in HEPA filter air purifiers. Yet, it’s not just the numbers that caught our attention – a little dispute with Dyson intrigued us to look deeper into this purifier model. Here is our review of the Levoit Core 300S.

#1 Auto Mode in Core 300S Air Purifier

While many purifiers, including the Core 300S, offer convenient features like auto and sleep modes, this feature also comes with a problem. The device categorizes 0-35µg/m3 as VERY GOOD, but in fact 35µg/m3 is 7 times higher than the WHO annual limit of 5µg/m3.

When the built-in sensor detects the air as VERY GOOD (below 35µg/m3), it automatically lowers the fan speed. In practice, it should clean the air at a higher speed to remove more pollutants, ensuring that PM2.5 stays below the WHO annual limit.

#2 Inaccurate Built-In Sensor

The auto mode feature relies on the built-in sensor to provide air quality data, then the question comes: is the sensor accurate? 

A built-in sensor only measures air next to the air purifier, often which has just been cleaned. This doesn’t necessarily give a good representation of the air in the room. An air purifier that is too weak to clean a room may still have cleaner air near the purifier.

We have seen a complaint from an Amazon user pointing out that the Levoit built-in sensor is inaccurate.

#3 False Claim on HEPA Filter Label

In August 2023, Dyson questioned whether Levoit EverestAir Smart True HEPA, Core 300, and Core 300S True HEPA air purifiers, along with their replacement filters, actually met HEPA standards. 

Levoit argued that their claims were originally based on independent data. However, they decided to permanently stop using those challenged claims, which meant that the Better Business Bureau would not assess the evidence. 

Since then, Levoit removed the term “True HEPA” from Core 300S and now emphasizes a 3-stage filtration process instead. 

Read more: Dispute Finds Levoit Falsely Claimed Filters As ‘True HEPA’ Grade

#4 Didn’t Publish CADR and Noise Levels on All 3 Speeds

On Energy Star Website The CADR of the Levoit Core 300 is tested to the AHAM AC-1-2002 standard and found a result of average 240 m³/h (141 cfm). Based on this result, the Levoit Core 300S would be suitable for a 20 m² room. 

However, they didn’t publish CADR and noise levels on all 3 speeds so it is difficult to know their performance on different speeds.

#5 Cost-Effectiveness

In terms of cost-effectiveness, it has an outstanding air cleaning performance for every dollar spent, reaching 1.6 CADR. This outperforms Smart Air’s Sqair, which achieves a 1.5 CADR per dollar, as well as Blueair Blue Pure 411i Max with its 1.4 CADR per dollar.

With less than US$150, it has a CADR of 240 m³/h and making it undoubtedly one of the best budget air purifiers.