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Monday, January 20, 2020

Clearing Australian air pollution

There is not much you can do to clear the outside air in Australia from all the pollution caused by bush fires short of taking climate change seriously but it is a different story inside your house.  The problem is all the tiny particles of soot, dust and other aerosols created by the fires.  There are P10's, P5's and even P2.5's.  These tiny particles are sucked deep into the lungs where they cause all sorts of problems.

The technology to clear the air in your house is the same that is used to clear particulates from smoke stacks.  Look at the smoke stacks in any modern country and at the most, they put out water vapor clouds that rapidly dissipate in the air and, of course Carbon dioxide.  It is called electrostatic precipitation.  Home units are sometimes called negative ion generators.  So how do they work.

The 220 volt AC is fed into a transformer that steps up the voltage.  (does anyone know what voltage they use.  Haven't been able to find the info).  The high voltage is then run through a rectifier such as a wheatstone bridge to give pulsating high voltage DC power.  If there is need to smooth out the power, a capacitor can be connected between the positive and negative outputs of the Wheatstone bridge.  The negative side is then run through a seriously strong resistor so that you can't get a shock (at least not a bad one) if you touch the spike.  the spike is where the electrons come off into the air and for reasons I won't go into, a spike is the best configuration to send electrons into the air.

The electrons stick to particles in the air, charging them and as the charged particles come close to surfaces, they are attracted and stick.

The positive side can  be grounded to your power supply ground but better still, put the grounding wire provided, with the metal end into a large shallow body of water with a pinch of salt in the water.

One of our sons had breathing problems when he was younger so we put one of these on a small shelf above his bed.  It wasn't long before the wall behind the bed turned black from all the charged particles that the electrostatic charge glued there.  With a grounded body of conductive water, you will see the water get grungy as charge particles are attracted to the water.  If this doesn't happen, you either have very clean air (unlikely) or you have an inferior  brand of negative ion generator.  Our son's breathing and his sleep was much improved.

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