Objectives Needle-free jet injectors are frequently used in dermatological practice. Injection-generated small-droplet aerosols could be harmful upon inhalation when chemotherapeutics, like bleomycin, are used. Here, we aim to explore jet injector-induced small-droplet aerosol formation of bleomycin in relation to air ventilation and to provide safety measures for clinical practice. Materials and Methods With a professional particle sensor, we measured airborne aerosol particles (0.2-10.0 mu m) after electronic pneumatic injection (EPI), spring-loaded jet injection (SLI), and needle injection (NI) of bleomycin and saline (100 mu l) on ex vivo human skin. Three levels of air ventilation were explored: no ventilation, room ventilation, and room ventilation with an additional smoke evacuator. Results EPI and SLI induced significant small-droplet aerosol formation compared with none after NI (0.2-1.0 mu m; no ventilation). The largest bleomycin aerosol generation was observed for the smallest particles (0.2-1.0 mu m) with 673.170 (528.802-789.453) aerosol particles/liter air (EPI; no ventilation). Room ventilation and smoke evacuation led to a reduction of >= 99% and 100% of measured aerosols, respectively. Conclusion Jet injectors generate a high number of small-droplet aerosols, potentially introducing harmful effects to patients and healthcare personnel. Room ventilation and smoke evacuation are effective safety measures when chemotherapeutics are used in clinical practice.