The investigators will define two separate groups of surgical procedures: 1.) an 'open group' in which mainly open anatomic lung resections will be included, and 2.) a 'minimally invasive' group in which mainly thoracoscopic anatomic lung resections will be included.

Both groups will then be randomized to either the performance of the surgical procedure under 'standard conditions' or to the performance of the procedure with the additional use of a smoke evacuation system.

During every procedure the hazardous smoke that is generated by the electrocautery in the surgical field will be collected through a tube at the height of the surgeons face. The smoke is then directly transferred to a mass spectrometer that is situated in the operating room (OR) and performs a real-time analysis of the chemical substances in the air. The degree of air pollution will be measured as well as the smoke evacuation systems' ability to reduce these hazardous chemical substances in the air can be evaluated.

Smoke samples will be continuously analyzed with a latest generation time of flight mass spectrometer in real time. Concerning the smoke evacuation device, the investigators will use the model IES 2 (Intelligent Evacuation System) from Erbe Swiss medical for this study.

Since this is only an observational study in which the investigators are only recording the type of surgery (i.e. open oder minimally invasive) and not recording sensitive patient data, the local ethics committee waived the need for an ethics committee approval of the study. In the end the smoke evacuation system does not have an effect on the patient or the procedure itself, but may rather influence the concentration of hazardous surgical fumes in the operating theatre.

Inclusion Criteria:

- All surgical procedures with a planned duration of more than 1 hour

Exclusion Criteria:

• Patients with a contraindication for electrocautery use
• Patients with Pacemaker or implantable cardioverter-defibrillator (ICD)
• Patients with an implanted neurostimulator device

All surgical procedures that will be performed during the study period at the investigators' department will be randomly allocated to either the performance of surgery with or the performance of surgery without the use of a mobile smoke evacuation device. Whether the procedure will be performed open or minimally invasive will be decided by the operating surgeon and is not part of the randomization process. During the respective surgeries, a mass spectrometer will be used to measure the smoke concentrations and its composition in the operating room.