The composition of plume produced during carbon dioxide laser endoscopic treatment for endometriosis was examined to determine whether it represented a hazard to the surgical staff. A total of 32 plume samples were collected from 17 women undergoing laser laparoscopic treatment for endometriosis and/or adhesions. The smoke was found to consist of particles having a median aerodynamic diameter of 0.31 micron with a range of 0.10-0.80 micron. The size range has two consequences: 1) using a human red blood cell as a model for all cells, it can be stated with greater than 99.9999% certainty that no cell-size particles, including cancer cells, are present in the plume; 2) particles in this size range are too small to be effectively filtered by currently available surgical masks.