Objective: To study the effect of activated carbon[url=www.coconutactivatedcarbon.com/]coconut activated charcoal[/url] on the purification of formaldehyde in the clean workshop return air purification device and its influencing factors. Methods: From May to June 2018, choosed 4 different commercial activated carbons (bamboo charcoal, 1-3 mm, 3-5 mm; coconut shell charcoal, 6-12 mesh, 8-16 mesh) to make 5 types of activated carbon purification net. In the simulated clean plant laboratory, the detection of occupational disease hazards was used to test the purification effect of different types of activated carbon purification nets on formaldehyde. Results: The purification effect of different types of activated carbon increased with the prolongation of purification time, and the difference was statistically significant (P