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AirDoctor 3500i Review: Data-Driven Testing

Derek Hales

Written By: Derek Hales

Updated on:

AirDoctor 3500i
98 Purification
97 Build Quality
85 Noise
100 Usability
93 Maintenance
96.6 Overall Score
Tested With Scoring System 1.1

Best For

  • Large coverage of 1,274 sq. ft.
  • User-friendly controls on the top of the machine.
  • The new AirDoctor app displayed great information and control options


  • Must use an AirDoctor approved filter.
  • More expensive relative to many other purifiers

Our Verdict

The AirDoctor 3500i is the latest model fromAirDoctorthat offers app connectivity for enhanced user remote functionality. It comes with all the great performance power of the AirDoctor 3000 but with the added Wi-Fi connection. Its coverage is outstanding, covering 1,274 sq. ft. with 2 air changes per hour.

However, this air purifier does come with some drawbacks. It’s on the pricier side of air purifiers and it requires AirDoctor’s proprietary filters. However, the benefit of the increased price is exceptional performance.

Filter Type: Carbon, HEPA
Coverage Area: 1,274 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)0.1 ppm
PM10 (1 hour test)0.2 ppm
Particles (1 hour test)15
AQI (1 hour test)1
Ozone Detected0.0 ppm
Filter TypeHEPA, Carbon, Pre-Filter, Ionizer
Coverage Area1,274 sq. ft. (118 sq. m.)
Max Wind Speed15.6 mph (25.1 kph)
Noise Test66.8 dB

Purification Performance

To test the purification performance of the AirDoctor 3500i, 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 1 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
PM2.558.4 ppm0.1 ppm0.1 ppm
PM1098.8 ppm0.2 ppm0.1 ppm

In our air purification tests, the AirDoctor 3500i was able to reduce PM2.5 to 0.1 ppm. This is 0.39 PM2.5 lower than the average of 0.49 ppm PM2.5, based on all of our air purification tests to date.

AirDoctor 3500i
AirDoctor 3500i

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

This level of purification power is something we similarly see in larger air purification systems. With this being a step down in terms of coverage area from the larger AirDoctor 5500i model, it didn’t sacrifice any of the purification power when packed into a smaller device.

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 AirDoctor 3500i, 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 AirDoctor 3500i generated 0 ppm. This is the same level as the average of 0 ppm, based on all of our ozone tests to date.



Unfortunately, there are no 3rd party filters available for AirDoctor. So you’ll need to buy the 1st party AirDoctor filters.

AirDoctor 3500i Pre-Filters

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.

AirDoctor 3500i Carbon Filter

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

AirDoctor 3500i HEPA Filter

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

AirDoctor 3500i 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 AirDoctor 3500i has a coverage area of 1,274 sq. ft.

Coverage Area

1,274 sq. ft.


340 CFM

Comparing the AirDoctor 3500i to the average, we see it has a notably larger coverage area. Across all air purifiers we’ve tested to date, the average coverage area is 749.19 sq. ft. and the average CADR is 292.49 CFM.

Wind Speed Test

Our wind speed test uses an anemometer placed directly on the air vents of the AirDoctor 3500i 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

8.0 mph

Maximum Wind Speed

15.6 mph

In our wind speed test, the AirDoctor 3500i was able to generate a maximum wind speed of 15.60 mph. This is 3.32 mph higher than the average of 12.28 mph, based on all of our wind speed tests to date.

The wind speed on the AirDoctor 3500i is definitely something to consider for this medium-sized air purification system. For context, the size above the 3500i is the 5500i, which is meant for larger areas, and has the same wind speed as the 3500i.


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.

PartBuild Quality

AirDoctor is a fantastic brand that builds reliable air purifiers out of sturdy plastic components. With the 3500i, you get a glossy white finished plastic that surrounds the body. It feels well put together and gives the impression that it’s built to last. Overall, the AirDoctor 3500i demonstrates exceptional build quality.


Noise Test

To determine the level of noise that the AirDoctor 3500i 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

43.1 dB

Min Noise

44.6 dB

Max Noise

66.8 dB

In our noise tests, the  AirDoctor 3500i generated 66.8 dB of noise at the max fan speed. This is 4.65 dB lower than the average of 62.15 dB, based on all of our noise tests to date.

Due to the higher wind speeds the AirDoctor 3500i creates, it carries a louder noise level. However, the noise level output is not that far off when compared to the average. To put this into perspective, our current testing data ranges from 72.50 dB to 46.00 dB. The AirDoctor 3500i is fairly close to the testing average when looking at the overall range.



The major update to this model is the wifi connectivity, allowing it to connect to AirDoctor’s app.



Setup was simple and easy. The most important step you’ll need to take with your new AirDoctor 3500i is removing the plastic cover from the filter.

AirDoctor 3500i Packaging
AirDoctor 3500i Packaging

This is a critical step that must be done before turning on the system.


Controls & Display

The controls on the AirDoctor 3500i are at the top of the system and displayed with a backlight panel. When pressing the buttons, they make an audible “beep” to signal the user that it has registered your input.

AirDoctor 3500i Controls
AirDoctor 3500i Controls

On the front of the air doctor, is the air quality indicator with an LED light ring. This ring will display the air quality index with either blue for good air quality, orange for moderate, and red for poor air quality.

Wireless Controls

What sets this model apart from the standard AirDoctor 3500 is its new Wi-Fi capability and app connection. The AirDoctor App allows you to remotely manage your Air Doctor’s performance and power settings. The app provides details about the air quality in your room and local weather information.

In The Box

AirDoctor 3500i Unboxed
AirDoctor 3500i Unboxed


The AirDoctor 3500i has an estimated yearly maintenance cost of $120. The following are the major maintenance tasks for the AirDoctor 3500i.

TaskDescriptionEst. Annual Cost
HEPA FilterReplace Every 8-12 Months$59.95
Carbon FilterReplace Every 8-12 Months$59.95
Pre FilterPeriodically clean and replace as needed$19.95

Size & Dimensions

The AirDoctor 3500i has the exact same dimensions as the AirDoctor 3000.

Height18.7″ (47.5 cm)
Length8.8″ (22.2 cm)
Width13.9″ (35.2 cm)
Weight18.0 lbs. (8.2 kg)


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

Manufacturer Specifications
Height18.7″ (47.5 cm)
Length8.8″ (22.2 cm)
Width13.9″ (35.2 cm)
Weight18.0 lbs. (8.2 kg)
FilterHEPA, Carbon, Pre-Filter, Ionizer
Noise Levels66.8 dB (max)
Coverage Area1,274 sq. ft.
Wi-Fi CompatibleYes
Warranty1 year
PriceCheck Price

Product Evolution

The new AirDoctor 3500i is the new series from AirDoctor that has the app connectivity. The Airdoctor 2000i, 3500i, and 5500i all come with Wi-Fi features that connect to a very informative app.

How does AirDoctor 3500i 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)0.1 ppm0.49 ppm
PM10 (1 hours)0.2 ppm0.74 ppm
Particles (1 hours)1561.04
AQI (1 hours)11.91
Ozone Detected0.0 ppm0.0 ppm
Filter TypesHEPA, Carbon, Pre-Filter, Ionizern/a
Coverage Area1,274 sq. ft.744 sq. ft.
Max Wind Speed15.6 mph12.4 mph
Noise Test66.8 dB62.2 dB

Generally, a strong indicator that the air purifier has exceptional purification performance is our 1-hour testing measurement. At 1 hour, the AirDoctor 3500i was able to reduce the PM2.5 to 0.1 ppm, easily beating our 1-hour testing average of 0.49 ppm. It had similar measurements for PM10, reducing it to 0.2 ppm after the 1-hour measurement. It then held those measurements into the 2nd hour.

AirDoctor 3500i
AirDoctor 3500i

Additionally, the app connectivity stands out for the AirDoctor product lineup. Not only does it provide remote handling, but giving the extra air quality information sets it apart from other air purifier apps.

Other Air Purifiers to Consider

Shark NeverChange

Shark NeverChange

The Shark NeverChange scored exceptionally well in display features with its large front-facing air quality meter and touchscreen controls on top.

The Shark NeverChange would be best for someone who wants a plug-in and forget air purifier that can give exceptional information on the surrounding air quality.

Oransi Mod+

Oransi Mod+

The Oransi Mod+ is the successor to the Oransi Mod.

This air purifier would be best for medium to large size rooms with its increased coverage to 1,361 sq. ft. and an improved CADR rating of 375.

Alen Breathesmart 75i

Alen Breathesmart 75i

The Alen Breathesmart is a medium-sized HEPA air purifier that comes with 3 different filter options.

The Alen Breathesmart 75i is a quiet air purifier that would be best for rooms that need large coverage but have to be as quiet as possible.


Can I wash the HEPA and Carbon filter on the AD3500i to extend the lifecycle?

No, these filters are not washable and should only be replaced with AirDoctor-approved filters.

How long do AirDoctor Filters last?

Depending on the environment that the system is operating in, it’s generally a good idea to replace the filters every 8-12 months. However, situations may vary and the AirDoctor App will alert you when the filter needs to be changed.

Should I leave my air purifier on all the time?

You can leave the system on 24/7 if you prefer. The AirDoctor 3500i does come with an “Auto Mode” that will adjust the fan speed according to air quality.

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.