
Smart Air - lispython
http://smartairfilters.com/
======
unholiness
I never thought I'd be pulled in by a product that essentially bills itself as
"Clean your air CHEAP with this one cool trick discovered by a college kid",
but they've executed well.

What they're offering is just an easy way to buy a fan and HEPA filter
($27USD, or 166RMB, as the FAQ freely admits). Even so, their website makes me
like instantly their business model, and because of their approach and
willingness to run workshops, I immediately trust goods from them more than
than I trust buying the parts directly from the manufacturer.

It will be interesting to see what they do with their new, loyal customer
base. I imagine they could easily start a filter-replacement subscription
service, where they send you as many new filters as you need for XXrmb/year.
If you're needing more than is profitable, they could add a phone call into
the process "to diagnose why your home is needing filters than it should".
This is the kind of honor system that only works if your customers already
like you. Assuming their product actually works, I think they will easily
achieve that.

~~~
talhelmt
Hey, this is Thomas--Smart Air is my startup. Thanks for the ideas! I'll
consider adding a subscription service. Several people told me at the
beginning NOT to publish my findings (at
[http://particlecounting.tumblr.com/](http://particlecounting.tumblr.com/))
because I should make money off of it instead. But I published it anyway
because I thought (1) if I don't make a dime, but people learn how to protect
their health without going broke, that alone is worth it and (2) there's space
for an air filter company that publishes data openly.

There's so much trust involved in air filters because it's almost impossible
to know if they're working if you don't have an expensive particle counter. So
we're hoping that our open data and methods will show that they can protect
their health without going broke.

~~~
tianshuo
Hi Thomas, I'm a Science and technology instructor for high school students in
Beijing, this could make a great project for them. Call me at
tianshuo_at_gmail_dot_com

------
simonsarris
This is a very neat idea, though I suspect they'll ultimately want a more
powerful fan.

Note that high quality air filters also have a carbon pre-filter that gets
changed more often than the HEPA filter, and having one ought to make your
HEPA filter last much longer, especially in somewhere like Bejing. They also
play a part in controlling odors.

This is what I'm currently using and love it to death. Note that the customer
photos with the "dirty" filters are actually the carbon pre-filter and not the
HEPA

[http://www.amazon.com/dp/B00440EKRG/](http://www.amazon.com/dp/B00440EKRG/)

~~~
acgourley
I'm still trying to reconcile the $300 price tag of yours with the price tag
of a carbon filter (5 on amazon) HEPA filter (70 on amazon) and box fan (30 on
amazon). Is there really 200 dollars worth of plastic, assembly, marketing and
IP in the the whispure? Or is there one important element I'm not accounting
for (perhaps fan power, fan noise, some kind of PID, or sensors to check
filter health)

~~~
gcb0
a quote from the movie with the mock history of dr kellogs:

health is the easy way to a fool's wallet.

that said I have 3 expensive of those filter at my home. not that one, 3 other
different brands. The main factor for my purchases were silence. and
ironically the only one that was silent is a discontinued sharp model that
sold for $150. all the $300 models are awful. specially the blueAir one that
focus all it's marketing on being silent.

~~~
Noxchi
> health is the easy way to a fool's wallet

No it's not, especially with a preemptive health solution (solving a problem
people don't feel they have).

~~~
jfoster
You seem to be suggesting that pre-emptive health solutions are a very
considered purchase, but isn't fear a major driver of such purchases? Perhaps
not unwarranted fear, but fear is also not very conducive to completely
rational purchasing behavior.

------
seanmcdirmid
See [http://iphone.bjair.info/](http://iphone.bjair.info/)

The air pollution ATM is at 366 PM 2.5 when this post was made. The chart now
tops out at 300 with the hazardous description; the US embassy got rid of the
crazy bad description given that the Chinese government wasn't so happy about
that.

We went all the way up to 800 and 900 last January; we got up to 424 just last
week. 0-50 is considered clean air, Salt Lake City institutes burn bans
whenever their AQI goes above...35. There was a scandal when it got to 55 or
so last year.

------
talhelmt
Hey, this is Thomas--I started Smart Air and the Particle Counting Tumblr that
preceded it
([http://particlecounting.tumblr.com/](http://particlecounting.tumblr.com/)).

Thanks for all the useful suggestions! Our main philosophies are to (1) not
rip people off and (2) be open about our data. I post data and testing methods
to Particle Counting on a regular basis.

Simon--you're right about the fan speed. We've been doing experiments with
more powerful fans, and we'll be coming out with a more powerful model soon.
It'll be better for bigger spaces, and it cuts the particle counts down a lot
faster. The fan is a bit more expensive though.

------
douge
These 20x20x4 inch HEPA filters are much better than standard 1 inch a/c
filters. They are the right size for putting on your box fan.

[http://www.ushomefilter.com/products/air-
filters/SC80-20X20X...](http://www.ushomefilter.com/products/air-
filters/SC80-20X20X4)

Shipping is free, and with the coupon code TWITTER10, you'll save some money.

------
gabemart
For someone living in a city with reasonably clean air and no smog problem,
does filtering the air in their living space provide any long-term health
benefits?

~~~
dmix
Negative ionic air purifiers may help with SAD (seasonal depression) [1]
similar to daylight bulbs. Research is somewhat inconclusive.

It also supposedly makes air have equivalent ionic levels to "country or
mountain air". Apparently in the city/offices the ion levels in the air are
quite lower than in rural areas which is harmful. This of course is the sales
pitch from the companies selling them.

But at the same time the filters kill bacteria and pet dander (which is always
good).

I found a HEPA air filter that contained negative ionizer for around ~$50 on
Amazon which I use in my home office.

[https://en.wikipedia.org/wiki/Negative_air_ionization_therap...](https://en.wikipedia.org/wiki/Negative_air_ionization_therapy)

~~~
eru
Why is killing bacteria always good?

~~~
Goopplesoft
Ah the perils of text language. You're not sure if he's referring to both
bacteria and pet dander or just pet dander.

~~~
eru
Yes, it's somewhat ambiguous. You don't even know if they kill bacteria and
they pet [verb] dander. English grammar is crazy ambiguous.

~~~
Goopplesoft
hah good catch, pretty crazy actually.

------
DanBC
200 rmb is about £20, or $32, or €24

------
DannyBee
Errr - this is expensive for what you get. Among other things, the CFM is so
low that it takes hours to reduce the particle rate any appreciable amount, as
their own tests show.

You'd do a lot better with a standard high velocity fan (also 35 bucks, and
you can get them cheaper):
[http://www.northerntool.com/shop/tools/product_200361823_200...](http://www.northerntool.com/shop/tools/product_200361823_200361823?cm_mmc=Google-
pla-_-Fans-_-
Floor%20Fans-_-2507402&ci_src=17588969&ci_sku=2507402&gclid=CKH_2N_exroCFQZyQgod5A4AFw)

You want to be changing the air at a much higher rate than they are.

They quote a 13.5 square meter bedroom. This is 145.313 square feet. If they
have 8 foot high ceilings, it's 1160 cubic feet.

In order to be changing the air so little as they are, my guess is this box
fan is ~40CFM, giving ~30 minutes between air changes.

For 30 bucks, you can get a 2000+ CFM fan (see above), and put the filter on
the intake side rather than the output side. This would change the air in the
room roughly _twice a minute_ , or roughly 60 times faster. There will be some
loss of CFM due to static pressure increase, but ...

They also probably want a cheap, washable, electrostatic pre-filter so you
aren't wasting the filtrating on easily caught particles. Otherwise, you are
just going to go through this hepa filter really quickly.

~~~
talhelmt
This is Thomas--founder of Smart Air. Thanks for the ideas!

I totally agree--we've been doing tests with more powerful fans, and the
results are great. We'll be coming out with a more powerful model soon. Of
course, it's a bit more expensive to get a more powerful fan.

We've avoided using pre-filters because we don't want to cut down on air flow
(and HEPAs aren't all that expensive), but we'll probably use a pre-filter on
the more powerful model.

About where to put the filter, is there a reason to put it on the intake side?
I've heard several people make that argument, but I've never heard a good
justification for it.

~~~
DannyBee
There are a couple reasons to put it on the intake side:

1\. Otherwise you are pulling dust particles directly into the fan
bearings/etc (though it may be that you don't have a good enough seal for this
to matter anyway). All this does is lower the life of the fan. This is one of
the reasons you see filters on the intake side of an A/C or furnace - to
protect the innards.

2\. If a non-dust particle gets dropped into the fan, with the filter on the
outtake side, it is likely to get propelled through the filter at high speed.
With the filter on the intake side, this will never happen (since it would not
hit the filter), and even dropping it near the rear of the filter is unlikely
to cause damage.

(There are other reasons that would matter more if this was an enclosed
ventilation system, but it isn't)

Note that without pre-filtering, i can't imagine these filters are really
lasting that long without being cleaned. Are you measuring static pressure
increase at all to see how long they last before needing to replaced?

HEPA filters are not usually meant to be sole filters and last a long time.
They are just too fine and load too quickly. Some form of coarse separation
(IE >5 micron particles) is usually necessary to get any real life out of
them.

------
ksec
I am actually looking for a solution where the filtering is done through water
rather then a HEPA filter, which needs replacing quite a lot in a environment
as bad as Bejing.

~~~
jmpe
Use aquarium air stones. The smaller the bubbles and higher the column of
water the better.

~~~
lostlogin
Wonder if a fully functioning fish take would be even better - if you get
plenty of plants growing, they will feed off the water/each other in my
experience. The rate of air injection would likely have to be higher than that
of a normal fish tank though? I used to run a fish tank with CO2 injection to
get the plants growing well. The best, cheap way of doing this was to put CO2
into the filter intake, that way big bubbles which escapes the diffuser were
blended up by the impeller of the filtration.

~~~
jmpe
AFAIK you could introduce mosses (Vesicularia and the likes) instead of higher
plants, they're not as CO2 dependent. Every aquarium tutorial I ever read
tells me that air pumps lower the CO2 content and you need injection as you
explain.

------
X4
I think that people in Beijing and other Asian or American countries should
stand up more often and force their governments to install filters on each
fabric's smoke pipe and charge those who don't comply with a big fine. You can
then open a petition that votes for using the money generated from that fine
to for deploying fuel-less car alternatives… Come on, tell me you're helpless
and dependent on your government and that your voice is not worth anything,
that you can't change your country.. If you agree sir, I'm sorry. Sorry that
you're not standing up for your rights. But then dear citizen, have the
courage and inhale the smog in all it's glory and purity.

The DIY Filter idea is great to have a transitional solution and I applaud the
startup for this idea. But a government, a country, a company, or a
stakeholder, none of them can make profit and money, when there are no trees
to cut, no clean air to breathe, no healthy citizen to employ, no educated
class to teach, no unpolluted earth for the seed and no will for change. Then
you've created the perfect environment for a colony of sheep that follows a
butcher who sells himself as a shepard.

~~~
lignuist
While I agree in general, one of the biggest sources (if not the biggest) of
dust in Beijing's air is the desert Gobi. It will be pretty hard to build an
appropriate filter. ;)

In my experience Beijing's air is really "special". Hot, humid, dusty. Not my
favorite environment.

~~~
seanmcdirmid
The dust is not as bad these days as 10 years ago; the tree planting in Inner
Mongolia and hebei has worked surprisingly well. These days, pollution from
artificial sources is a much bigger problem and we've mostly forgotten about
dust, but sand storms still occur occasionally.

------
chopin
Axial fans, especially those for household purposes do not offer the required
pressure drop of approx. 300 Pa
([https://en.wikipedia.org/wiki/HEPA#Specifications](https://en.wikipedia.org/wiki/HEPA#Specifications)).
Axial fans have typically a high throughput but low max pressure difference
(see eg. [http://www.adrianagarcia.me/wp-
content/themes/twentyeleven/a...](http://www.adrianagarcia.me/wp-
content/themes/twentyeleven/axial-fan-curve)). HEPA filters require radial (or
centrifugal) fans for acceptable throughput.

As well, a HEPA filter becomes clogged very rapidly without appropriate
prefilter. This means that the pressure drop required increases considerably
definitely beyond reach of any household fan.

~~~
Havoc
>Axial fans, especially those for household purposes do not offer the required
pressure drop of approx. 300 Pa

It might fall short of the official specs, but its difficult to argue with
their results.

What kind of prefilter would one need? I'm thinking of DIYing this...

~~~
chopin
>It might fall short of the official specs, but its difficult to argue with
their results.

For this one would need to know the exact measurement setup. For real world
performance it is important to know the approximate exchange rate of air of
the room. The throughput of the fan across the filter must be considerably
higher than that.

>What kind of prefilter would one need? I'm thinking of DIYing this...

First of all, you would need a radial fan to overcome the required pressure
drop. As for the prefilter, I am from Europe, which has probably different
standards than the US, but some overview is provided here:
[http://www.filtration-
engineering.co.uk/air_filter_testing.h...](http://www.filtration-
engineering.co.uk/air_filter_testing.htm) . For my clean room set up I had a
EU5 prefilter combined with a EU9 main filter. Afair, laminar flow boxes for
dirty environment (i.e. not supposed to be used within a clean room) have EU5
(or the equivalent) prefilters as well.

~~~
Havoc
Interesting. Why do you have a clean room if I may ask? I'm guessing data
recovery?

~~~
chopin
I was in making photographic (those with silver halide) plates in the 90's.
That's a wet chemistry process which does not tolerate any dirt in the final
product. I made a good deal of the required machinery on my own so I have some
basic knowledge on clean room design (albeit a bit rusty).

------
gpurkins
Nice! I had read something similar for a wood workshop here:
[http://woodgears.ca/dust/air_cleaner.html](http://woodgears.ca/dust/air_cleaner.html)

Seems to be quite effective.

Also, if you're into woodworking, woodgears is probably one of the best, if
not the best on the net.

~~~
lignuist
I stumbled upon woodgears.ca after watching woodwork Youtube videos. This guy
is so awesome.

Here is his 3D Pantograph:

[http://www.youtube.com/watch?v=vtm4u583YOQ](http://www.youtube.com/watch?v=vtm4u583YOQ)

[http://www.youtube.com/watch?v=iUGkroZus_Y](http://www.youtube.com/watch?v=iUGkroZus_Y)

------
f7t7ft7
Can't you just do this with a normal box fan and a hepa air filter you buy for
7usd at the market?

~~~
donutreceipt
From the FAQ:

You can! We have links on our Particle Counting blog. 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
Taobao for the cheapest 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 (200RMB)
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.

~~~
drivingmissm
The irony is that running all of these filters is consuming electricity, which
in turn means more coal-fired power plants and even dirtier air for everyone.
Beijing should move to clean up the environment.

~~~
ericd
The irony's not very strong, since these can clean a lot more than they
contribute via electricity consumption.

------
peferron
Just ordered one, and also a Dylos DC1100 particle counter. I'm often in
Shanghai, and pollution can get pretty rough even if we have it better than in
Beijing. I'll make sure to measure the hell out of it and see if it really
works. :)

Edit: I know the particle counter ($200) is 6 times the price of the air
purifier, which can seem ridiculous; but to me it makes much more sense to do
that than to buy a $300 air filter and just pray for the best while having no
clue at all about what's really going on.

------
scarboy
I like this product, it appeals to a market where there isn't much money to
spend and is probably effective.

The consumer air purifier market is a mess. There is so much misinformation
and fake reviews out there that it's impossible to make a decision.

Each company runs dozens of smear sites against everyone else. All the Amazon
reviews look fake. All the companies seem to have something wrong with them.
It got to the point that when I was doing me research I just gave up and
decided to not buy anything.

------
pervycreeper
Are particles the whole story when it comes to air pollution, or do you have
to worry about gases, too?

Also, what would be a good source for obtaining HEPA or carbon filters in
Canada/USA?

~~~
talhelmt
Hey, this is Thomas, founder of Smart Air.

Excellent question! Particulates are very important, but gases can be a
problem too. We talk about gas pollution in our workshops, and I've written
about it on Particle Counting:

[http://particlecounting.tumblr.com/post/60881490803/the-
limi...](http://particlecounting.tumblr.com/post/60881490803/the-limits-to-
counting-particles)

However, I don't know of home filters that target gases.

~~~
dopkew
There are various indoor plants that are said to help with indoor pollution.

~~~
yaddayadda
[http://www.ted.com/talks/kamal_meattle_on_how_to_grow_your_o...](http://www.ted.com/talks/kamal_meattle_on_how_to_grow_your_own_fresh_air.html)

[http://www.slideshare.net/jaymeattle/how-to-grow-your-own-
fr...](http://www.slideshare.net/jaymeattle/how-to-grow-your-own-fresh-air-
ted-2009-talk-presentation?type=powerpoint)

TED presenter Kamal Meattle argues for: \- Areca Palm \- Mother-in-law's
Tongue \- Money Plant

------
ck2
Or strap a $1 central A/C filter to a $10 box fan.

~~~
jrockway
That is not going to filter out PM2.5. Those filters only exist to protect the
internals of the A/C unit from large debris.

------
luke_s
This is good, but why is it in English, not Chinese? If you want to reach
people wouldn't the best way be to post on the various forums netizens like to
hang out in?

~~~
brianherbert
Maybe they are trying to connect with the expat community.

------
switch007
The copy at the top seems a bit wordy to me.

How about this?
[http://i.imgur.com/whD4yWh.png](http://i.imgur.com/whD4yWh.png)

------
hoprocker
Crazy. I was just thinking about doing this in my place a few months ago. I
was going to actually build a little container that fit in a window and have a
HEPA filter from McMaster-Carr (or wherever) sitting behind computer tower
cooling fans, as these fans are designed to be quiet and low-power. This
design has a ready-made chassis, though.

------
aidenn0
You get a lot more flow with a squirrel-cage fan; I don't know a cheap source
of those though.

------
jmpe
I've used HEPA filters when I built an IV glove box a couple of years back.
Don't recall the numbers, but I needed a fair bit of pressure from the air
pump to get a decent flow rate. Somehow I don't think a fan will do it.

~~~
icelancer
Did you even read the data that shows otherwise?

~~~
chopin
Did you even bother to look up basics of HEPA filters? They require an initial
pressure drop of 300 Pa
([https://en.wikipedia.org/wiki/HEPA#Specifications](https://en.wikipedia.org/wiki/HEPA#Specifications)),
which is beyond reach of any household fan. When the filter bcomes clogged,
the pressure drop will increase even higher.

Updated: Grammar

------
octatone2
This depresses me.

~~~
DanBC
What about it depresses you?

The fact that people need air filters? Or something about the way these people
are doing it?

I really like their website. They're open and honest about not being experts,
and about how they do things, and how they want corrections and additional
information. They sell you a kit _if you want it_ , but they make no secret
about it being really easy to do by yourself.

~~~
malandrew
It's a classic case of negative externalities caused by stupid human decisions
and a complete disregard for the commons. People have been shitting in the
commons so long in Beijing that the particulates in the air are crazy high.
Everyone feels like this have to have a car instead of pushing hard for
effective public transportation. Since everyone has to have a car, it hurts
everyone on buses because the traffic is so bad the busses can't get anywhere
on time anymore[0]. Then everyone has a building that is heated by coal,
instead of making an effort to upgrade the buildings to some form of heat that
isn't going to dump thousands to millions of pounds of particulates into the
atmosphere.

Instead of solving the problem at the root, everyone takes an every man for
himself approach to the problem like the one described by the OP. The
government should provide some sort of tax incentive to every building willing
to upgrade their heating to something cleaner and should tax the hell out of
cars in the city and put that money towards public transportation

FWIW, I lived in Beijing back in 2005/2006 and had a solid smoker's cough
after a year. It's truly disgusting how everyone is effectively poisoning each
other there.

[0] Furthermore, the design of the onramps and offramps on the ring roads are
such that they cause a cascading locking condition once the level of traffic
hits a certain point. When the line to exit a ring road gets long enough, it
blocks the on ramp. This causes locking to cascade through the whole city.

~~~
seanmcdirmid
Beijing is the victim of geography where pollution is often trapped in an
inversion; a problem like Salt Lake City in the states. Beijing has much fewer
cars per person than say Seattle, and the problems arise from too many people
more than too many cars, coupled with shitty cheap oil refined poorly leads to
a huge problem in aggregate. On the other hand, the subway system has been
built up nicely, and is expanding very quickly, though it is always wicked
full and not very comfortable by western standards. Beijing's traffic problems
simply boil down to too many people and cars and not enough road with nowhere
really to build more.

Old coal boilers are another problem, and a lot of pollution blows in from the
Hebei country side and gets stuck in Beijing without an outlet. All buildings
in Beijing are heated by the city, so it's not even the building owner's
option to be more efficient. Beijing is slowly switching over to natural gas
for heating but the transition will take a couple years to finish.

The AQI right now is down to 50 where it was 340 only a few hours ago. I can
only imagine we got some wind to blow out the bad air all of a sudden.

------
mathgladiator
Cool; for a couple of years now, I've purchased furnace filters and used a
simple box fan. It handles a great deal of particulates in the air (compare
rooms during a sunny day with an without the fan is very stark)

------
krunk4ever
Pretty cool idea, but given that the target audience are people living in
China, why is the site in English instead of Chinese? Is the target Americans
or other English speaking people living in China?

------
neals
First though: Why would I need this. Then I saw something about Bejing, where
I believe there's lots of smog(?).

Would this help against lots of smog?

~~~
seanmcdirmid
If you live in Beijing, you need an air filter. We were about to buy an
expensive one, but this is quite nice; we might just go with it.

------
DigitalSea
I love simple and affordable alternatives to otherwise expensive solutions
like this. This is a fantastic idea.

------
MichaelTieso
Could have used this when I lived in Xi'an for a year. Coughed the majority of
the time I was there.

------
keyanzhang
here's a discussion on zhihu.com (in Chinese):
[http://www.zhihu.com/question/21951887](http://www.zhihu.com/question/21951887)

------
reion
Guys at [http://aaaiiirrr.com/](http://aaaiiirrr.com/) are doing the same
thing, but Open source.

~~~
dm2
I don't see anything on their website. Looks like a new install of wordpress.

~~~
reion
Sorry - it was [http://aaaiiirrr.org/](http://aaaiiirrr.org/) not .com

------
caiob
Why put the price in RMB?

