Homemade air ionizer which not producing ozone…?

I want to know how to make an air ionizer which not producing ozone .I understand air ionizer and ozone device is very alike in
construction.The ozone produced in the air by ozone devices is dangerous because of nitrous gases ...my ionizer I don't wanna make ozone
So how can I made an air ionizer which not producing ozone?
I understand,for producing ionized air,we need
high voltage.For producing ozone ,we need HV too .So ,how to avoid to not producing ozone
though?
Please give me details;is not clear for me the difference between that 2 phenomena
So more clearly .What must be the range voltage between minim and maxim to have an
efficient ionizer and in the same time to not producing ozone ?