For people living in apartments, fresh air is a  precious resource. To keep the air healthy in  these spaces, what you can do is to replace  your HVAC filters more often than normal,  

install ventilation fans, and keep the house  free of dust to reduce particulate matter in  the air. 

If you live in a home with more windows, you  can open them at regular times each day to  let fresh air in. However, you have to take  note that outdoor pollution can also enter and  increase PM2.5 levels indoors. Improving the  filter used in your HVAC system can  significantly reduce the amount of PM2.5  entering your home. Houses with bigger  spaces can also put up plants to help improve  the air. 

At your workplace, you need to make sure  that the building’s ventilation system is  working efficiently and is able to ensure an  effective flow of fresh air so that the stale air  inside the workplace can be dissipated. 

Aside from good ventilation, our activities can  also have an impact on our indoor air.  

Cooking, for example, generates a high  amount of PM2.5. Maintaining good ventilation  is crucial to lessen health risks.