HEPA really isn’t good, the way hepa filters are manufactured and discarded is really bad for the environment. A better alternative is electro static and ionizing filters that are cleanable, like airdog provides. The tech isn’t new, but the industry isn’t interested in not making money on disposable hepa filters..

Wasn’t the issue with the ionizing filters the production of ozone? I recall that being the reason the Ionic Breeze units fell out of favor.

How is Airdog any different?

Smaller Ionizers release really small amounts of ozone, airdog isn’t mainly using ionizing, the bigger filter is the electrostatic one. Ozone machines are dangerous though, but it’s no secret. You really shouldn’t use any ionizer in a non ventilated space for a long time though, it will build up

Ionizing air filter are a health hazard on their own: https://pubs.acs.org/doi/10.1021/acs.est.1c02582#

I don’t know input HEPA production, but if you throw them into household trash here in Germany they simply get burned.

From the article, there doesn't seem to be much of a conclusion rather than more studies are needed, since the technology is poorly understood. And I agree, the idea is that ionization happens naturally, it does, especially after lightning strikes, which then pulls particles downwards to the ground and nearby objects, the same happens indoor. This is good, particles <2.5ppm are attached to objects and usually stay attached and can be removed by wiping, the article you linked to targets gasses and their reactions to ionization in industrial ionizers which is the poorly understood parts. The article also doesn't compare home HEPA efficiency vs home Ionization, so it's not clear which is better or worse. Most modern air pumps also use ionization to clean the air, mainly using plasma (since it's the fastest), so ionization is already widely used in homes.

The problem with HEPA filters are the destruction of resources to make them, the bad controls of their quality and their short lifespan (Cheap home HEPA filter needs exchanging every 3 months) and their high price (>30€).

Yes, most of the HEPA air purifiers are trash, offered like as a "subscription service" due to the large cost and short lifespan (6 months in average) of the filters. But there are other options like Sharp KCA50EUW [0] with an advertised filter life span of up to 10 years. A more trendy and smart offering is Electrolux PA91-404DG, albeit it has a shorter filter lifespan (could not find the number now but if my memory is right then it's 2 years).

[0] https://sharphome.eu/en/sharp/airpurifierhumidifier/en-kc-a5...

If I understand correctly the air purifier you linked to is exactly one of those ionizing air purifiers producing unintended unresearched chemicals.

HEPA purifiers aren't trash, they are simply producing trash. For me that is a lesser evil to producing potentially dangerous chemicals in my home. Just like I accept using FFP2-masks that aren't reusable in contrast to cloth masks used at the start of the pandemic. There are other places where saving trash is has less negative impact than health products.

That sharp one is something I've missed and it also does Ionization, impressive lifetime, thanks for sharing that.