Surgical Smoke Carries Persistent Free Radicals and Reactive Chemistry, Study Finds

Every time a surgeon’s electrocautery pencil touches tissue, a plume of smoke rises into the operating room air, carrying with it a complex cocktail of chemicals that has long been treated as little more than an unpleasant nuisance. A new study published in the journal Air Quality, Atmosphere & Health now shows that this smoke is far more dangerous than its appearance suggests. Researchers systematically characterized surgical aerosols generated during operative procedures and found that the fine particles they contain are not inert contaminants but chemically reactive materials, laden with persistent free radicals and endowed with a measurable capacity to generate reactive oxygen species, the aggressive molecules that drive oxidative stress and inflammation in living tissue.

The research team, led by Yu-Chieh Wang of National Sun Yat-sen University in Kaohsiung, Taiwan, together with colleagues from clinical and academic institutions in Taiwan and Thailand, focused their analysis on the PM1 fraction, particles with diameters of one micrometer or less. These ultrafine particles are of particular concern because they are small enough to penetrate deep into the lungs, past the body’s normal filtering defenses, and to deposit in the delicate alveolar regions where gas exchange takes place. Size-resolved aerosol samples were collected directly in operating rooms, capturing the real-world conditions in which surgeons, nurses, anesthesiologists and other staff work day after day.

Once collected, the PM1 samples underwent an unusually thorough chemical interrogation. The researchers measured the carbonaceous composition of the particles, distinguishing organic carbon from elemental carbon using established thermal-optical protocols, and quantified the concentrations of polycyclic aromatic hydrocarbons, a class of compounds formed during incomplete combustion that includes well-known carcinogens. They also determined the heavy metal content of the particles using high-resolution inductively coupled plasma mass spectrometry, a technique sensitive enough to detect trace elements at extremely low concentrations. Electrocautery, after all, works by heating tissue and metal electrodes to extreme temperatures, and previous work has shown that the procedure can even liberate molten metal particles from surgical implants.

The most striking findings, however, came from electron paramagnetic resonance spectroscopy, a technique that detects unpaired electrons and is therefore the gold standard for identifying free radicals. The EPR analysis confirmed the presence of persistent free radicals on the surgical particles, a category of long-lived radical species more commonly associated with environmental pollutants such as diesel exhaust, coal fly ash, incense smoke and biomass burning particles. Unlike ordinary free radicals, which react and disappear within fractions of a second, persistent free radicals can survive on particle surfaces for hours, days or longer, traveling intact through the air and into the respiratory tract.

The team went beyond simply detecting these radicals and quantified the intrinsic ability of the surgical aerosols to generate reactive oxygen species in aqueous solution. The ROS-generating capacity of the PM1 fraction was measured at 1.03 × 10¹⁸ ± 1.86 × 10¹⁷ spins per gram, a figure that places surgical smoke squarely within the range of recognized hazardous reference particulate materials. For comparison, the researchers noted that this value lies between those reported for SRM-2786, a fine urban dust standard issued by the US National Institute of Standards and Technology, and coal-fired power plant fly ash, a material whose oxidative toxicity has been extensively documented in laboratory animal studies.

This comparison carries a sobering implication. Environmental health scientists have spent decades establishing that the toxicity of airborne particulate matter correlates poorly with mass alone and much better with chemical reactivity, particularly the oxidative potential of the particles. Regulatory frameworks, however, still largely rely on mass-based metrics. The new results suggest that surgical smoke, which has historically escaped the kind of scrutiny applied to traffic or industrial pollution, deserves to be evaluated by the same reactive chemistry standards. The authors argue explicitly that surgical smoke should be regarded as a chemically reactive aerosol rather than an inert particulate contaminant, a reframing with direct consequences for how operating room air quality is monitored and controlled.

The mechanism by which these particles could harm the body follows a well-understood pathway. When inhaled particles carrying persistent free radicals come into contact with the aqueous lining fluid of the respiratory tract, the radicals can catalyze continuous cycles of redox reactions, generating a sustained flux of reactive oxygen species such as hydroxyl radicals and superoxide. These molecules attack lipids, proteins and DNA, triggering inflammatory signaling cascades. Because operating rooms are enclosed spaces with limited air exchange during procedures, and because surgical staff are exposed repeatedly across long careers, the authors warn that sustained inhalation of surgical aerosols may induce severe airway and inflammatory responses, underscoring the need for control measures to mitigate occupational exposure in surgical environments.

The study also situates itself within a growing body of literature on surgical smoke hazards. Earlier investigations have quantified particle concentrations during tonsillectomy and breast surgery, surveyed the inconsistent use of smoke evacuation systems in operating theaters, and catalogued the volatile organic compounds and viruses that can survive in surgical plumes. What distinguishes the new work is its integration of source-focused aerosol chemistry with radical spectroscopy and health risk assessment, providing a mechanistic bridge between what is emitted at the surgical site and what happens once those particles reach human tissue. The researchers describe the reactive aerosols as transient carriers of persistent free radicals that act as continuous sources of reactive oxygen species upon interaction with aqueous environments such as respiratory tract lining fluid.

The practical implications for hospitals are significant. Smoke evacuation systems, high-filtration respiratory protection and adequate room ventilation are already recommended by several professional bodies, but compliance remains uneven worldwide, partly because the hazard has been perceived as minor or poorly characterized. By demonstrating that surgical smoke exhibits oxidative potential comparable to regulated combustion pollutants, the study gives occupational health officers a concrete, quantitative basis for treating electrocautery plumes as a genuine respiratory hazard. The authors emphasize that the chemical reactivity of the particles, not merely their mass concentration, should determine how exposure risk is assessed, and that this sustained redox activity is central to understanding the health consequences of chronic exposure.

For the millions of healthcare workers who stand over electrocautery fields every day, the message of this research is clear: the haze that rises from the surgical site is chemically alive in the most unwelcome sense. It carries combustion-derived carcinogens, trace metals and long-lived radicals capable of generating oxidative stress long after the plume has dispersed. As the evidence accumulates, the operating room may come to be seen not as a pristine clinical environment with an occasional smoky inconvenience, but as an occupational setting with an air quality problem that demands the same rigor applied to factories, highways and power plants. The study was supported by the National Science and Technology Council, Taiwan, and the authors report no competing financial interests.

Subject of Research: Chemical characterization and health risks of electrocautery surgical smoke aerosols in operating rooms

Article Title: Emission characteristics of electrocautery surgical smoke in the operating room: polycyclic aromatic hydrocarbons, metals, persistent free radicals, reactive oxygen species generation, and health risk assessment

Article References: Wang, Y.-C., Ching, W.-C., Wang, C. C., Lee, C.-L., Khemawoot, P., & Ching, W.-M. (2026). Emission characteristics of electrocautery surgical smoke in the operating room: polycyclic aromatic hydrocarbons, metals, persistent free radicals, reactive oxygen species generation, and health risk assessment. Air Quality, Atmosphere & Health, 19(9), Article 206. https://doi.org/10.1007/s11869-026-02095-1

Image Credits: AI Generated

DOI: 10.1007/s11869-026-02095-1

Keywords: surgical smoke, electrocautery, persistent free radicals, reactive oxygen species, PM1, polycyclic aromatic hydrocarbons, heavy metals, operating room, occupational exposure, electron paramagnetic resonance, oxidative stress, air quality