Air purifiers don't need to run 24/7. If you get Xiaomi (I have these so I'm confident, but I would bet some others have the same), they are Wifi connected and controlled from mobile phone. On the phone, you can select schedule, and if you take whole home automation set, with air quality sensors, you can make even a lot more detailed automation of when to run, like when you're on the way home, turn it on 30 minutes before you arrive, etc.
I have one air purifier in each room. Set the bedroom ones to work overnight, and living/working room ones to work over the daytime but turn off at night. That can be easily overridden if pollution outside is really bad and a single air purifier can't handle it by simply turning others on by app or touch button on the box.
I prefer Xiaomi not only because they are cheap, but because they have air quality sensors and display with current information, can be controlled from phone, and have easily obtainable filter cartridges which cost about 800-900 baht each and last (in my case) about 9 months with schedule enabled, or about 6 months if running 24/7.
One word of caution with XIaomi - they have global and China versions. They use different cloud locations. So if you have China version, all is in Chinese and App has to be set to mainland China. I have all items Global versions, so I can control them all from same app. You'd need 2 phones if you had a mix. Chinese versions are usually a little cheaper than Global version.