Does anyone know what can be used to filter out the pollution and PM2.5 particles for a car aircon? Is it possible to use a 3M Filtrete or something else?

You can buy cabin filters that are designed to filter out PM 2.5. "D Protect Filter Nano-Shield Series" seem to be OK and they have cabin filters available for many different models of vehicle on Lazada, they cost around 400 depending on the size of the filter. Your aircon won't be quite as powerful using one of these instead of the paper cabin filters, but it's worth losing a little bit of power.