I personally would not use a personal air purifier – all of them generate ozone. They may be advertised as generating a low level, but here are my concerns:
– How do you know if your personal unit is performing correctly, either while new or as it gets older? As far as I know, there is no simple home test for measuring the ozone level being discharged.
– What is the effect on the body and lungs of inhaling low levels of ozone at very close quarters over extended periods of time? Especially for a person with already compromised lungs this is critical.
– What do scientific, peer reviewed studies show about effectiveness and safety of personal air purifiers? I am not able to find any such studies. Most of what is published is from manufacturers.
We have asthma and allergies as well as bronchiectasis in our family (3 households.) We use a whole-house charcoal plus HEPA air filter systems. In our main home, it is part of our climate system (sorry, I don't know the brand.) In our seasonal home (a tiny house) we use a properly sized portable Honeywell unit. The keys to effectiveness are keeping the doors and windows closed as much as possible and absolutely changing all filters on or ahead of schedule, and buying the right filters for the unit. They have made a huge difference in our symptoms and comfort. My daughter has a portable one for her workplace as well. My son-in-law did a little research and added a UV unit in each bedroom as well because he is very concerned about viruses and their small boys.
As for the Covid recommendation to introduce fresh air to keep virus numbers low, we have the maximum fresh air intake on our ventilation system & rune the fan at low speed at all times. We also open windows whenever wind and air quality measures allow, regardless of low outside temperatures.