A variation on the standard Mountain Breeze ionisers that was aimed specifically at helping combat VODS (VDU Operator Distress Syndrome), a rather dramatic title to explain the fatigue of sitting in front of cathode ray tube monitors all day.
The concept was that the CRT had a positive charge on its surface that was counteracted by the ionisers generation of negative ions.
There's a probability that many of the VODS symptoms were caused by long hours, flickery displays, chemicals liberated by hot components (early VDU's gave off strong "electronic" smells) and being slouched in front of the computers while wearing synthetic fabric clothing, on plastic seats on nylon carpet. Basically electrostatic hell, with this little unit doing its best to nudge the polarity in your favour.
The main feature that differentiates this ioniser from the classic one is the use of an LED as a power indicator. Up to that point ionisers with indicators had used neon lamps for their ease of driving, and an LED gave the unit a modern "electronic" look in keeping with the computer era.
A green LED of that time was based on gallium phosphide technology and they were very dim, even at 20mA, so to drive one from the mains wasn't as simple as using a resistor and diode. It had to be a capacitive dropper, and that was pretty unusual for that time.
Other than that, the rest of the circuitry is a standard 11-stage Cockroft-Walton multiplier with 22 10nF 630V capacitors, 22 1N4007 diodes and two 10 Megohm safety resistors on the output to the needles.
It's worth mentioning that this arrangement is probably only practical for 220-250V use, as lower voltages would require a much larger multiplier.
Ionisers impart a strong electrical charge into air by applying a high voltage (several thousand volts) to sharp points. This results in electrons attaching to air molecules, and dust which then gets repelled away from the sharp points (like-charges repel) creating a slight draught. The negative charge neutralises positive charges and also precipitates dust to ambient surfaces like walls and floors.
Although considered quack products by some cynics, largely due to the use of snake-oil sales techniques in the past, the units do have a distinct effect - although their indiscriminate dust precipitation does make a mess in their vicinity.
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