Seeing how the haze is not going away anytime soon and how my family and I aren’t going to spend money on getting a proper commercially available filter, I thought that I should try and make some kind of cheap filter for use at home.

My primary purpose of this filter is to weed out the pm2.5 particles. This particles are so small (2.5 microns), they are thought to go straight into the blood stream, and as we all know, smoke inside blood = bad. Particles larger than that are easily filtered out by conventional means, but the pm2.5 particles will need specialized filters, like N95 masks and HEPA filters.

Interesting note – N95 masks should be used when pm2.5 particulate concentrations reach 40 µg/m3. Current levels are above 200+ µg/m3.

Lots of products use HEPA filters, but they’re relatively expensive and are also expensive to replace. I was looking for a cheaper solution when I stumbled across this sentence on the US’s EPA website – ‘These fine particles also have a great affinity for water’. So, I thought, why not use water as the filter? It’s cheap, readily available and seem to want to trap fine particles.

2 Types of Water Filters

I figure that there are 2 ways of creating a filter.

Method 1 – The Blowy Filter

As its name implies, it’s basically rigging something up to blow air onto the surface of a body of water.

Blowy filter mk1
Basically a CPU fan blowing air onto a body of water

Pros – Relatively cheap, easy to create, high volumes of air
Cons – Inefficient

You can either simply get a fan and blow into a pail of water, or if you prefer a little more finesse, cut up an old container and stick cpu fans on it.

Some of you may already see a problem with the idea, and yeap, it will be inefficient because many, if not most, of the lighter particles may not even come into contact with the water.  The best workaround I can think off at the moment is to basically have the fan blow straight down onto the surface of the water. It should also be covered to encourage further contact.

This is probably a fun project if you’re the type who likes to tinker, but if you don’t mind spending a little bit of money or you prefer something a little more straight forward, I suggest you use the 2nd method.

Method 2 – The Bubbly Filter

This is basically using an aquarium pump to push air through a pail of water.

Pros – Efficient, idiot proof
Cons – May be costly, low air volume

If you have an old unused aquarium air pump, well then, you’re in luck. If not, try getting a pump that can push high volumes of air, especially if you’re gonna be using this in large areas like the living room. Noise may be an issue if you’re thinking of using it in a bedroom, so do take that into account.

Also, you want the bubbles to be as small as possible to increase the surface area of contact between the air and water. Don’t need air stones, but you could block of the end of the tube and poke smaller holes around it.

Air Control

In my humble opinion, using either setup with open windows, etc, would, obviously, defeat the purpose of having made the filters in the first place. You can use it as it is in an air-conditioned environment to clean the air in the house, but that’s would waste a lot of electricity, so, you should use these ideas to create a ‘gateway’, allowing you to bring in clean air into the house, even with the windows and doors closed.

Ideally, there should be a way to funnel the the air into the air filter. The problem is of course that the entire window needs to be opened for the air to come through, while things like drilling a hole to make way for a pipe isn’t going to be practical. Best way I can think off is to leave one of those mini-top windows open for your pipe.

Experiment

Anyway, these are just ideas, and they are by no means proven replacements for full-on air purifiers. Do try them out and see what happens. Do share your results by commenting!

Have fun, and relax, just breathe =)

Update – It would seem like the best way to do this is to do a combination of the 2.

The problem with the ‘Blowy’ method is that the water is still. Adding a way to splash water around to create more surface area contact would require adding a pump…which can big expensive and/or too big, depending on your setup. It would definitely be too big for the little rig I posted above.

I guess it would be good if we could combine the 2 methods. So, you still have the fan blowing air onto the water, but this time, we’ll add an air pump. The bubbles created will produce water movement and splashes, while the air being pumped as bubbles themselves will get cleaned as they’re bubbling up.

Time to go shopping for an air pump =D