The area your ionizer covers is bigger than the ground area of my house. Can I just use one in the hallway to cover all the rooms on one floor?

Unfortunately, no. Ions cannot travel through walls. And the amount that could pass through a doorway is too few to properly ionize the room beyond. You really need one ionizer for each room to be covered. 

How many ionizers do you recommend per household?

It is not absolutely necessary to install an ionizer in every room. We usually suggest that you start with one in the room you live in most (usually the lounge), and a second one in the bedroom. (And maybe a personal model for an office.)

If I use my ionizer in a small room, will it generate too many ions?

No. Firstly, you can't overdose on negative ions. And in any case, we recommend that the ionizer is underworked and having spare capacity rather than just coping - not because it will put any strain on it, but everything that happens in the room has an effect on the ion levels. Say you switch on the tv, have friends round or have a full scale party. All of these things use up negative ions. By having a powerful model it will supply enough ions for all situations.

Does it cost much to run?

We have designed our ionizers to be extremely efficient. They only use a quarter of a watt of electricity. That works out at about 4000 hours or 24 weeks continuous use for just 1kW (1 unit).

Are your ionizers noisy?

No, there are no moving parts to generate noise. The only sound is a very faint hiss from the needles where they ionize the air. And you have to listen very carefully, close beside the ionizer even to hear this.

Can I leave it on all the time?

Yes, our ionizers are designed for continuous use. And the running cost is negligible.

Why have Astrid ionizers got 4 needles when others have up to 16?

There have been many different ion emitter designs varying from just one single needle to "carbon brush" emitters that effectively have thousands of points. In reality it doesn't matter what method is used. The actual specifications of the complete unit is the important issue, like the ion output and the area covered.
It's a bit like a band member asking "how many transistors are in my amplifier?" when what he's really interested in is the sound output and quality.
We experimented with various options and 4 needles is the most effective design for our ionizers.

Will I need to buy replacement parts, such as filters or needles?

No, Astrid ionizers do not use filters, and are fitted with special non-replaceable needles designed to last the life of the unit.

How long will the ionizer last?

Because we use very reliable solid state components in all our models and there are no other moving parts, there is virtually nothing to wear out. Our ionizers last for many years.

I've heard that small ingestible ions are especially good for health. Do Astrid ionizers produce them?

Yes, the emitter needles generate small, mobile ions that are breathed and absorbed by the body. 

Can your ionizers be described as negative ion generators?