This time of haze offers an excellent opportunity to both keep your indoor air clean and insulate your house a little bit. Use clear tape to seal cracks and gaps around windows, or use rolled-up toilet paper (push it in with the flat end of a small spoon handle) to fill the gaps. On doors, open the door and on cleaned wood, run a piece of duct tape from top to bottom where the door hinges, sticking one half to the frame and the other half onto the door – when the door is closed, it will create a nice seal against air flow.
Don’t run your exhaust fans unless absolutely necessary. The air pulled out by the fan needs to be replaced (“make-up air”), and air is drawn into the house through gaps and cracks in the building envelope. When the air is hazy, it gets pulled in. When it is warm and humid outside, you are pulling this air into the house, creating an extra load for the air-conditioners to cool and dry the air. This also leads to more condensation issues and the related mould problems.
So, seal the gaps and don’t run exhaust fans in the kitchen and bathrooms when not required!