Try to wear a KN95 and crack the window open? Don't recirculate the air on your AC.
KN95 is available everywhere with cheap price and I have a lot in stock, so this is no problem.
Goggle and hazmat suit are also available with reasonable prices; something like US$5 for hazmat suit and US$3 for goggle. However, wearing these make one feels like you're in war with someone. Further, I might have dinner with him as he'd stay one night in Phnom Penh.
Thank you guys for your kind advices. I will take your advice by wearing a KN95 mask, open car windows and keep safe distance. The most important things is I have 3 doses of vaccine. So I think I'm rather safe. A one-week self quarantine after the event will also keep people around me safe too.