Do I need to get visa just for a few hours' stop at the airport in Beijing

I'm travelling from Seoul to Bangkok via Beijing with one stop at the airport in Beijing. I'm not going to leave the airport at all, just to wait for the next connection to BKK by Air China. Do I need to get visa just for a few hours?
I'm a Polish citizen staying for 2 months in South Korea (in accordance with 90-day limitations; no visa required).
I appreciate your prompt reply. Happy Lunar New Year!
Ewa