This is the second Alen product I have purchased in the last few months. I have owned the 45i for a couple of months and was very satisfied with its performance.

We have wanted an air purifier for a couple of years and after doing some research decided the Alen models were the best option. We were motivated by construction in a unit next door that has kicked up some dust plus we live in an older building so also general health concerns. 

Concurrent with ordering the 75i, I also purchased an air quality monitor that measures HCHO, PM2.5, TVOC and AQI. I have found the general rating from the 75i and the air quality monitor measures to be consistent.

The 75i works as advertised and knowing our indoor air quality is excellent make us feel more comfortable that we are taking that extra step to improve our overall health.