根据我对空气净化器原理的了解,要减少颗粒物污染的关键在于HEPA 滤网。虽然我只在中国住一年,我真不舍得花8000民币买一台超贵的净化器,我觉得我可以自己制作属于自己的空气净化器。
我在这里给出净化器有效的数据(1, 2, 3, 4),这篇是教你如何制作DIY空气净化器。
#1 购买一台风扇
非常重要的一点,风扇的前面最好有一个平面,这样可以方便把HEPA网绑上去。这是我花58元购买的风扇。
#2 购买HEPA滤网
这是我购买的第一个HEPA 滤网,价格108元人民币。
我测试所有我能找到生厂商的HEPA网,希望可以找到一个既能捕捉更多颗粒,同时风阻更小-也就是可以通过更多空气的HEPA。我用激光测试仪做了测试,结果表明这款HEPA 的效果非常好。因为我一次性批量采购,所以这 个HEPA 比我初次买的HEPA 要便宜,放在我的淘宝店(还有Smart Air 官网)供有需要的人购买。
#3 卸掉风扇前面突出的部分
把风扇的前网拆掉,前网是通过一个卡片固定的,如果有钳子会更容易操作。
把风速开关调到高档,然后把开关旋钮卸下。旋钮突出会使HEPA不能很好和风扇贴和。没了旋钮,可以通过插拔插头来开关风扇。
#4 用绑带将HEPA 滤网系上,你就成功制作了你自己的DIY空气净化器了!
用固定带把HEPA绑在风扇的前面,专属于你的空气净化器就完成了!
风扇中间的铁棍可能会稍微插入滤网。我的测试结果表面这个问题并不会影响HEPA 的效率,为了安全你也可以把它锯掉。当然,要是能够找到没有铁棍的风扇是最好,也是我正在销售的(淘宝网)。
这DIY净化器价值166人民币(27美元)。你的下一个问题一定是:DIY空气净化器和那些昂贵的8000人民币的空气净化器比较,效果如何呢?点击这里观看测试视频,用更给力的风扇效果会更好吗,和其他品牌比较起来效果如何。
你也可能会想:滤网不是应该在风扇的背面吗?其实,我的直觉一直是‘放前后并不会有差别’,但测试的结果竟出乎我预料。
划重点:DIY空气净化器步骤
- 购买一台风扇;
- 购买HEPA滤网;
- 拆掉风扇前网;
- 将HEPA滤网固定在风扇前侧。

Thanks for sharing. Does this work for filtering out the Covid-19 virus particles in air aerosols? If I use such a purifier while I stay in a hotel room where the windows cannot be opened, is it going to be effective?
Hi Serena. Yes, HEPA filters can also capture virus particles, and so can capture COVID-19. There has been research done by the CDC in the US which shows that installing HEPA filters in schools reduced COVID transmission, so they can help. If you use them in your hotel room, just make sure that you still take other precautions like hand-washing and wearing masks. Air purifiers are just one of the solutions to reducing COVID transmission!
More info:
1. Can HEPA filters capture COVID?
2. CDC study shows air purifiers with HEPA filters reduce COVID transmission
Breathe safe,
A humidifier’s main purpose is to restore moisture to the air in your house. It achieves this by injecting water vapour into a room, which can be visible or not. Continue to fill a reservoir with water to keep the humidifier operating. The mechanism converts the water into a fine mist and expels it into the surrounding air. v Humidifiers are most effective in dry environments because they replace moisture in the air. The Most Effective Air Purifier Living in an arid area can cause dry skin, throat irritation, sinus problems, nosebleeds, and breathing difficulty. A humidifier can assist.
Is there any reason why your filters are relatively very thick compared to other air purifiers? I definitely like that your filters are thick – it feels robust. But I noticed that other HEPA filters are usually thin and made of less paper. Does it mean that your filters are much more robust & has better longevity or is it a simple trade off in cost-effectiveness (i.e. cheaper material but equal effectiveness)?
Great question Ken. Thicker filters mean deeper pleats (folds) in the HEPA filter. Overall, this means more HEPA filter material can be packed into the HEPA filter, allowing for a higher airflow and longer lifespan of the filter.
The reason Smart Air’s filters may appear thicker is because we design all filters to have maximum airflow – thicker means higher airflow.
Seeing as we can’t search through comments, I apologize if this has been asked:
How much difference does it make if we don’t pull the grating and knobs off, or if the filter is not the same size or cannot be fastened flush with the fan?
It seems odd to me that filters will be the same dimensions as fans as they come in all different shapes and sizes!
If you look at the photo you can see that all that matters is that the filter is as big as the whole area that air comes out of. So that circular indented area where the fan blades are, your filter just needs to be at least as big as that. It won’t matter that the filter is bigger.
Can I use air cooler without water instead of standard fan for the diy cooler?
If I use a hepa filter for my furnace, and have the furnace fan on all the time, is this an effective air purifier?
Hi Shea, the only issue is that in order to push enough air through the filter, you need a fan powerful enough. For sure if you use a HEPA filter there, it will help to clean air going through, but is the amount enough to clean up the whole room, that depends on how strong your fan is and how large your apartment is.
Thank you so very much Thomas because you have saved me some financial hardship trying to come up with the money for a purifier. Temporarily out of work and the thought of needing at least 3 devices for my home then the cost of filters. Oh gosh! Your DIY air purifier came at the right time for me. May God so richly bless you…
Hi. Will your fan plug into Australian powerpoints?
Hi Mira, the plug on our DIY fan is not the same as Australia’s plug type, but with a simple adapter (similar to a travel adapter) you will be able to use the fan in Australia!
hello, I have purchased a diy1.1 air purifier. Which side of the hepa filter should face the fan?
According to the Smart Air website, there are instructions on the edge of the diy1.1 filter instructing placement of the filter on the fan side; that is, where the air flow exits the fan:
https://smartairfilters.com/cn/en/product/hepa-filter/
Hi! I’m in ACT Australia and currently due to extreme conditions, hundreds of fires are burning 1-3 hrs away. This is blanketing our city for weeks.
Needing to attempt to make this amazing alternative as I cannot breath easy in my smokey apartment with my children.
My question is, after I purchase my fan and hepa-filter, can I also attatach a carbon filter as well as 2x general filters to the one machine? I would be very grateful to know exactly the right combination and order (if there is one) please…so that all the ‘bad’ is captured effectively.
Thank you so much!
Hey Britt, can’t imagine what you and your family are going through in Australia because of the fires!
To answer your question, there can only be 1 filter attached to the fan at each time — either a HEPA or a carbon filter. If you attach more than 1 filter, it will not be effective because a fan’s strength isn’t enough to support both.
Hye Ethel, just quick question: what depth of HEPA filter should be? I have options 20mm, 25mm, 30mm, 35mm?
Hi Britt I am in Australia experiencing the fire conditions in Canberra; where did you buy your HEPA filter?
Hi Britt I am in the ACT also where did you get your HEPA filter?
Kate
Thanks for this! I was inspired to build my own. Q: do you recommend combining HEPA and activated carbon filters with a regular box fan, or would that put too much strain on the motor?
I’m running it with both at the moment, but I don’t even know if it’s pulling the air through at sufficient volume to be effective, since I can’t feel the air flow pushing out the front.
Thanks!
Hey Rory, you can combine a HEPA and carbon filter on a box fan but the best way to make sure it is effective is to get an air quality monitor!
Hi, this maybe a silly question. I just made a DIY air purifier similar to instructions here. How much of air flow should we be able to feel at the front of the HEPA filter ? Little or none at all as I am getting almost none.
Hey Muhammad! This is a very common question for DIY air purifiers. Even if you can’t feel a lot of air coming out of your DIY, it doesn’t mean it’s not working. With the original DIY that Tom made, it also felt like very little air was coming out, however tests proved it to be effective. Check out this video of Tom showing this: https://www.youtube.com/watch?v=JpfpZofUzNo&t=7s
To ensure you’re getting the maximum air possible out of the purifier, make sure there’s a good seal between the fan and the filter, and that no air is leaking out of the back of the fan.
Breathe safe!
Hello! I had a similar problem to Muhammad’s – little to no air flow out of the front of the filter and significant flow out of the back of the fan (even after taping up all of the side vents in this particular desk fan.
What do you recommend to correct for this? I’m in the USA, so I don’t believe I have affordable access to the same fan listed in the instructions in this blog post.
If you’re in the USA, then you’re in luck! I suggest you get yourself a box fan and a large furnace filter. These fans are extremely powerful and very affordable in the US. They should be a great option for you!
Hi Thomas,I want to buy your HEPA Filter through Taobao website. However i have a big question : the last product is an air purifier machine or a fan having air purifier function. Is this product still a fan? Does it make cool anymore?
Hey Vivi, Tom’s out doing nerdy stuff so I’ll reply on his behalf! With the HEPA filter attached, the airflow is much less than a regular fan, so these DIY purifiers don’t have a strong cooling effect. However since the HEPA filter is detachable from your fan, you should be able to remove the HEPA filter at any time to turn the DIY air purifier back into a fan.
Thank for your reply. Finally the fan is not a fan anymore, right? The fan becomes an air purifier?
Hi, I wanted to back/order the Squair on Kickstarter but am I one day too late? The photo says it ends on July 5th, which is today, but I can’t seem to find a link to order… thanks!
Hey Mona, you just missed the Kickstarter, unfortunately! The campaign ended midday on the 5th July! If you want to be the first to know about pre-orders, sign up to our exclusive mailing list here
Finally the fan+filter is to be fitted as a fan (pumping air towards you) or as an exhaust fan (pumping air outside) ?
Is possible to have those ones in México City ?
Hi Daneil! We can ship to México City, but shipping costs can be pretty steep. What we suggest is you pick up a HEPA filter from our store, and source a local fan in México City, to save on shipping! More info: https://smartairfilters.com/cn/en/shop/worldwide-orders/
thanks a lot, I will do it. we are also interested in becoming a tester and create data for México and all LatAm countries. we are an IOT network that wants to help solving air quality problems in our regions. this is our website wndgroup.io , let us know how we can collaborate.
Hi. Where’s the best location to place the diy air purifier? I’m not sure if it needs a different air path vs the regular purifiers. Thanks. Janet
Hi there. I have done a similar thing ihere in Chaing Mai but instead of using a Hepa filter I used Filtrete air con paper made by the company 3m. Do you think this would also be an effective way of cleaning the air?
Yes, you can use the 3M AC filters for your air conditioning! We have actually tested this, but are yet to write up a report on it. What we found was that using the paper on air conditioners was effective at removing around 80% of PM2.5 in a small 10sqm room. However the effectiveness will depend greatly on how powerful your AC is and how often you change the filter paper.
where in chiang mai did you get the filter paper? Everyone of my mates leaves this time of year because of the smog. I will be returning later in the year but i want to prepare for next year
Are the HEPA filters washable? Or do you have to replace the filter after 6 months or so?
Good question Glenn! We wanted to know the answer to that, so we ran tests and published the results. Read about whether or not you can wash HEPA filters here.
I really enjoy that you are sharing technical proof in the article. I do a lot of drywall (gypsum) wall work and have been doing this same thing for almost 20 years. I use the 20in box fans that are sold everywhere (in America) for $25 or less and furnace air filters $7-20 depending on quality and vendor. This allows work to be done in single rooms with the doors closed keeping the dust from invading the rest of the home. For $30-40 (US) I have great air cleaning comparable to commercial units costing $130-400. I also get very affordable filters
WOW That is awesome marvellous and outstanding. I do prefer this site for many diys!
I am from Malaysia.
In the consideration of expensive international shipping cost for a cannon fan, I would prefer to purchase the fan locally. Please advise me if I could use an
exhaust fan with the air flow rate at 830m3/hour, using both HEPA filter and activated carbon filter for purifying my newly renovated house?
Do you have your filters and such available for purchase in North America? I’ve enjoyed navigating around your website! Thank you for all the work and publishing the information.
Hey Craig, glad you’ve found the info on our site useful! Right now we don’t have outlets in North America, although we can ship to individuals through our online store (although be warned: shipping is often more than the cost of the filter itself!)
We’re always looking for distributors to spread our low-cost solutions and the knowledge that clean air doesn’t need to cost an arm and a leg, and North America is definitely within our sites if you know anybody who might want to help out!
Terrific! Many thanks for sharing your work.
Woah, Your Post is very usesful, I’m From VietNam, I will try to make it