Starting from December 23, 2020, all Chinese and foreign passengers (excluding children under 3 years old) who take flights from Los Angeles to China, are required to take nucleic acid and IgM antibody tests at following designated facilities in Los Angeles 2 days prior to the departure date, and apply for a green health QR code.
--- From The Consulate General of The People's Republic of China in Los Angeles

Los Angeles County:
Orange County:
Rowland Heights Office (羅蘭崗辦公室)

17506 Colima Rd, Ste 201
Rowland Heights, CA 91748
Irvine Office (爾灣辦公室)

980 Roosevelt, Ste 200A
Irvine, CA 92620