Where to apply if you work in CERN, CH, and live in Fernay-Voltaire, France?

Hello. My son is a Serbian citizen working in CERN laboratory, Switzerland, and he lives in Fernay-Voltaire, France, on the very border between Switzerland and France. Can he apply for Chinese Visa in Zurich, or he must do that in Paris? The purpose of his traveling is a scientific conference in China, and he possess the relevant documents. Thank you very much in advance. L. Gligorov