Frequently Asked Questions

Where do you ship?

We ship anywhere in India and now also internationally. Please get in touch with us if you are outside India and we will get you a shipping quote.

How long does shipping take?

If you are in Delhi, it should take about 1 or 2 business days. For anywhere else in India, it will take about 5 to 6 business days. For Kathmandu, if we ship via air, it will take about 3 to 4 business days and if we ship via road, it will take about 10 business days.

Are you experts in air pollution?

No. Thomas, our data guru, is a professor in psychology at the University of Virginia. But we’re firm believers in honest presentation of empirical data. Our philosophy is that no one should believe us just because we say so. Instead, we openly publish our data and methods so you can see how we reach our conclusions and judge for yourself. And we own a particle counter.

Are you saying your DIY air purifiers work better than the expensive brands?

In our tests, the Cannon DIY performed just as well as the other big-brand purifiers! We’re not saying our DIYs are the most effective purifiers on the market, but what we are saying is that big brand purifiers aren’t necessarily any better. What we can say is that the DIY purifiers outperform all other purifiers we’ve seen in terms of cost-effectiveness. If particulate pollution is your primary concern (it’s our main concern!) and your bedroom is 15 m2 or smaller (most are), then the DIY filters we sell perform about the same as (or in the Cannon’s case, better than) the expensive brands.

Why can’t I just order the filters and fans myself?

You can! We have links in our Air Pollution knowledge base showing how you can do this! We’re more committed to spreading the knowledge that HEPA filters are a cheap way to effectively combat air pollution than we are to making money, so we’d never discourage anyone from buying the same parts elsewhere.

We just try to make the parts easier to get for people who don’t want to scour shops for the best filters. People have also emailed us saying that some stores stop carrying fans in the winter and that some HEPA manufacturers don’t sell in small orders. We buy in bulk so we can offer a low, flat rate that includes shipping anywhere in Mainland China. By buying with us, you also know that you’re getting HEPAs that we tested personally for effectiveness.

What’s the pre-filter for?

The pre-filter goes before the HEPA and filters out larger particles. This lets the HEPA focus on filtering out the smallest particles without getting clogged up by the big ones. We don’t include pre-filters on the Original DIY because the fan isn’t as strong as the Cannon. However, if you own the Original DIY and want to use a pre-filter, you can order them individually on our site.

Are you making money off this?

Not tons. So far we’re making enough to pay modest salaries to the people on the team, although Thomas is still working full-time for free. Any leftover cash goes to buying testing equipment and to the development of our soon-to-be commercially produced affordable air purifier.

I don’t feel much air flowing out the front. Is that normal?

Yes. Tests show conclusively that the DIY purifier still cleans the room air (such as all 200 days of longevity test data here).

How often should I change the filter?

Big purifier companies have nice-sounding numbers for HEPA longevity – 6 months! But what is that based on? And if a HEPA lasts 6 months in Sweden, will it last 6 months in Beijing? To get to the bottom of it, Gus tracked how much particulate his DIY Original removed in his Beijing apartment every day for 200 days.

Results? In real Beijing air, effectiveness dropped significantly after about 140 days (almost 5 months) at 8 hours a day or about 1,000 hours total. So we suggest changing your filter before this. See the full results and method here.

Remember that this result may not hold for the Cannon. So now we’re doing a Cannon longevity test!

Should I run the purifier while I’m out of the house too?

Thomas tested this by setting a Cannon to turn on and off automatically in an empty room over the course of six days, and recorded how quickly particulates rose and fell. On average, the Cannon cut .5 micron particulates in half in 10 minutes. By 20 minutes, it removed 80%. That’s pretty fast, so unless you have noticeable symptoms there’s no need to leave it running while you’re not at home. It’s fine to turn the purifier on when you get home. See the full results and method here.

Can I turn the purifier off when I sleep? How long does it take for the air to get dirty again?

Even in a room with the doors and windows closed, our tests found that particulate levels increased very quickly after the purifier was turned off. Dirty air is entering our homes constantly, even though we can’t see it. That’s why we don’t recommend turning the purifier off while you sleep. See the full results and method here.

Don’t see your question answered? Get in touch and we’ll get back to you as soon as we can.

Smart Air low cost purifiers

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.

Certified B-Corp air purifier company