$30 Box Air Purifier Review – Shocking Results

When I started Smart Air in 2013, the cheapest air purifier I could find cost over $600. That’s why I started shipping a simple, effective DIY Air purifier that cost just $30.

But since then, more and more purifiers priced around $30 have been appearing on the market. Here’s just one example called the “Diqu purifier”. It’s a small, white, box-like purifier that ships for just under $30 (198RMB) in China. In this article, I’ll cover just how good it is.

First Impressions

The Diqu box purifier was originally advertised at 465 RMB ($70), but I paid just 200RMB. I was impressed it was this cheap. After unboxing, I found a small, 35cm tall air purifier, with a reasonable but not great build quality. Here’s the Diqu purifier alongside Smart Air’s DIY air purifier.

But what I really care about is the how well this air purifier clean the air. To answer that, we ran CADR tests for the Diqu, and compared it to our DIY purifier, which also costs around $30.

The $30 Air Purifier Test

Smart Air’s engineer intern Joseph ran clean air delivery rate (CADR) tests on both purifiers to measure their effectiveness. In these tests, we burn a cigarette in a closed room, run the purifier for 20 minutes, and track the reduction in particles over this period.

The results weren’t pretty. The CADR for the Diqu purifier was about 30% of the DIY1.1. But perhaps we don’t need such a high CADR? Maybe a CADR of 26m3/hr is enough?

Unfortunately not. Based on a CADR of 26m3/hr, the Diqu purifier can clean a room that’s just 3.1m2 in size. Just how big is that? It’s roughly the same size as a king sized bed.

Compare that with the DIY1.1, and it can clean a room that’s 10.5m2 in size. That’s roughly the size of an average apartment bedroom. It can comfortably fit a king-sized bed along with a table and drawer.

Why is the Diqu Air Purifier’s Performance So Bad?

After opening up the Diqu air purifier, I found a small, flimsy looking air filter inside.

This filter measured just 21x17x3cm in size.

That’s far smaller than the filters in most purifiers, and means the Diqu air purifier can’t push out much clean air. A small filter also means it will need replacing more often.

What About the Diqu’s Ionizer Function?

The Diqu also has an ionizer feature. This is advertised as increasing cleaning efficiency and performance. However, the truth is that ionizers can actually increase formaldehyde and PM2.5 in your home.

Read more: what are ionizers and why you should avoid them »

Bottom Line: Diqu $30 Box Air Purifier Review

The $30 Diqu air purifier is less than 1 as effective as a DIY air purifier. It’s ionizer feature may actually increase indoor air pollution levels. We wouldn’t recommend this purifier as a cost-effective solution to breathe clean air.

Smart Air

Update: it’s worth noting that 2 years after purchasing the Diqu air purifier, it disappeared from online e-commerce platforms. Replacement filters are also unavailable. I suspect this purifier was a one-off, short term sale by the sellers taking advantage of an opportunity. Without the ability to purchase replacement filters, this purifier cannot be used long term.


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Smart Air is a social enterprise that creates simple, no-nonsense air purifiers and provides free education to protect people’s health from the effects of air pollution. We are proud to be the only certified B-Corp dedicated to fighting air pollution.