Expecting a baby with thai gf. How risky is Chiang mai?

In terms of safety etc, if we were to live in chiang mai long term, and stay inside with purifiers for the 3 bad months, how much risk are we taking? The reason for wanting to move was cooler weather, lifestyle, infrastructure etc vs samui where we were living.

Baby is expected in 7 months, we don't want poor health risks for ourself or the child, but also like chiang mai a lot. Great housing options/prices too. I have never visited in Feb-April however.

Moving date for us would be around April 5th, which I've heard is the worst and last month?