The objective is to provide an assessment of the literature discussing particulate matter size and plume emission rates. A review of published articles was conducted, and 11 studies were identified. Early studies demonstrated that all lasers emit smoke within the alveolar hazard zone (0.1 μm–27 μm). Recent studies concluded that higher plume emission counts are seen near the treatment site, during long procedures, while using cryogen spray cooling, and with laser hair removal. Sapphire contact cooling, pre-laser lotions, and smoke evacuators help to minimize plume. Further investigation with larger sample sizes is recommended to confirm these findings.
Key points
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Lasers produce different sized plume particles ranging from 0.1 μm to 27 μm, and these varying particle sizes impose different health risks.
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Factors that affect plume aerodynamic particle size include distance from the laser, plume water content, laser wavelength, and additional laser settings.
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Plume concentrations vary by laser device and treatment indication.
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Predictors of high plume concentrations include close vicinity to treatment site, long procedure duration, and cryogen spray cooling.
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The N95 and N99 surgical masks and smoke evacuators can minimize exposure to surgical smoke. Smoke evacuators must be held close to the treatment zone.
Introduction
Medical laser treatments have grown rapidly in the last 30 years across multiple medical specialties including dermatology, plastic surgery, otolaryngology, obstetrics and gynecology, urology, ophthalmology, and dentistry, amongst others. Surgical smoke, or plume, is generated by all lasers, and studies have demonstrated that plume consists of 95% water and 5% particulate matter (PM). The PM is composed of volatile chemical compounds as well as tissue particles and transmissible infectious agents [ ].
Various heat-producing devices emit different particle sizes after impact [ ]. Smaller particles are more likely to carry hazardous chemicals, and larger particles may transmit bacteria and viruses [ ]. Additionally, PM aerodynamic size dictates where particles can deposit within the respiratory tract and subsequently cause direct pulmonary injury [ ]. Coarse PM is defined as having a diameter between 2.5 and 10 μm. These particles settle in the upper respiratory tract. Fine (0.1–2.5 μm) and ultrafine (<0.1 μm) PM deposits within the tracheobronchial tree and alveoli, termed the alveolar hazard zone [ ], causing irritation and parenchymal damage [ , ]. Ultrafine particles can evade host immune mechanisms, translocate across cells, and be absorbed into the bloodstream [ ]. Understanding these distinctions of particle size according to laser device is important when selecting appropriate personal protective equipment (PPE).
Although much has been written about the microbiological and chemical components of laser smoke, there is a paucity of literature discussing laser PM size and emission counts. This summary aims to provide an evidence-based evaluation of pertinent studies describing airborne PM size as well as emission rate and concentration across various laser devices. Microbiological and chemical compounds are outside the scope, and we direct the reader to previous review articles for this information [ , , ]. Secondary objectives are to present applicable information related to smoke evacuation for hazard reduction and to highlight areas in which further investigation is warranted.
Methods
A literature search was performed for peer-reviewed articles indexed for MEDLINE on the National Library of Medicine PubMed Database from January 1970 to December 2022 using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol [ ]. Search items included “laser”, “laser surgery”, “laser smoke”, “laser vapor”, “plume”, “surgical smoke”, “mean aerodynamic particle size”, “particle size”, “ultrafine particle”, and “smoke evacuator” in 9 combinations. Studies met inclusion criteria if they discussed aerodynamic particle sizes, plume concentration, or plume generation rates. In vivo, in vitro, and ex vivo studies were included as were studies conducted in all medical specialties. Study titles and abstracts were reviewed for relevance, and those that were outside the scope of this review were excluded. Each study selected underwent evaluation and data extraction followed by grading based on the Centre for Evidence-Based Medicine, Oxford [ ]. For consistency, all PM sizes are reported in micrometers (μm) and all plume count values (concentration and rate) are rounded to the nearest one.
Results
Eleven studies from the dermatology, ophthalmology, dental, and obstetrics and gynecology literature are included (6 ex vivo, 4 in vivo, and one both ex vivo and in vivo). Table 1 lists the studies analyzing laser plume aerodynamic size [ , ], and Table 2 shows experiments that evaluated laser plume concentration and rate [ , ].
| Authors | Design | n | Sample tissue | Plume measuring technique | Laser settings | Aerodynamic particle diameter (μm) | G |
|---|---|---|---|---|---|---|---|
| Hahn et al, [ ] 1995 | Ex vivo | a | Bovine eye globe corneas | Laser light-scattering technique | ArF Excimer (193 nm, CW, nonfractional ablative) | Mean: 0.11 farthest from the cornea, 0.149 closest to the cornea | 4 |
| Taravella et al, [ ] 2001 | Ex vivo | 2 | Human corneas (98 particles examined) | Electron microscopy | Excimer (308 nm, CW, nonfractional ablative, pulsed frequency 6 Hz, 160 mJ/cm 2 ) | Mean: 0.22 ± 0.056 SD | 4 |
| Freitag et al, [ ] 1987 | Ex vivo | 11 | Sheep, closed chamber | Anderson cascade impactor | Nd:YAG (1064 nm, CW, varying energies 15–75 W) | Mean: 0.54 | 4 |
| Dayan et al, [ ] 2021 | In vivo | 3 | Human cutaneous tissue, fractional resurfacing, dermatology clinic | PCE calibrated particle meter | Er:YAG (2940 nm, fractional ablative, coagulation mode) | Most particles in the 5–10 range, UFP present in plume | 4 |
| Kunachak and Sobhon, [ ] 1998 | Ex vivo | 10 | Human laryngeal papilloma | Electron microscopy | CO 2 (10,600 nm, nonfractional ablative, 10 W) | Range: 0.5–27 70% particles 0.8 | 4 |
| Nezhat et al, [ ] 1987 | In vivo | 32 | Human endometriosis laparoscopy | Marple personal cascade impactors | CO 2 (10,600 nm, CW and pulsed mode, nonfractional ablative, 15–30 W) | Median: 0.31 Range: 0.10–0.80 | 4 |
| Authors | Design | n | Setting | Plume measurement device | Smoke evacuator | Laser | Particle count (concentration or rate) | G |
|---|---|---|---|---|---|---|---|---|
| Levin et al, [ ] 2021 | Ex vivo, in vivo | 6 | Ex vivo pig skin tattoo removal, in vivo human tattoo removal | TSI model 3007 condensation particle counter, TSI SidePak Aerosol Monitor (0.01 to >1.0 μm) | — | Pigs: KTP (532 nm, 2.4 J/cm 2 ), Alexandrite (755 nm, 5.5 J/cm 2 ), Nd:YAG (1064 nm, 4.7 J/cm 2 ) Human: KTP (532 nm, 1 J/cm 2 ), Ruby (694 nm, q-switch, 4–5 J/cm 2 ), Nd:YAG (1064 nm, 2 J/cm 2 ), picosecond pulse duration for all lasers | Outside treatment room range: 20,000–30,000 PPC Treatment room mean: 91,000 PPC Maximum concentration in the breathing zone : 400,000 PPC | 4 |
| Chuang et al, [ ] 2016 | Ex vivo | a | LHR, terminal hair samples in air-tight glass chamber | Condensation particle counter, unspecified | ULPA smoke evacuator held at 2.5 cm | Alexandrite (755 nm, 3 ms pulse duration, 20 J/cm 2 ) Diode (810 nm, 30 ms pulse duration, 30 J/cm 2 ) | Baseline air: 15,300 PPC LHR peak at operator level: 435,888 PPC LHR peak at patient level: 145,386 PPC LHR + smoke evacuator at operator level: 69,976–129,376 PPC | 4 |
| Eshleman et al, [ ] 2017 | In vivo | 12 | LHR, dermatology clinic | TSI Model 3007 Condensation Particle Counter (0.01 to >1.0 μm) | PlumeSafe Turbo filter, held at 30.5 cm | Alexandrite (755 nm, 3 ms pulse duration) + cryogen spray cooling, Diode (810 nm, 30 ms pulse duration) + pre-laser lotion | Waiting room mean: 14,957 PPC Treatment room mean: 22,917 PPC | 4 |
| Ross et al, [ ] 2018 | In vivo | 11 | LHR with various cooling techniques, dermatology clinic | TSI 8525 portable condensation particle counter (0.02–1 μm) | — | Alexandrite (755 nm, 3 ms pulse duration, 8–12 J/cm 2 ) Nd:YAG (1064 nm, 20–30 J/cm 2 , 10 ms pulse duration) | Concentration at operator level with — Cryogen spray cooling: 400,000 PPC Refrigerated air cooling: 35,0000 PPC Sapphire contact cooling: 3500 PPC | 4 |
| Dayan et al, [ ] 2021 | In vivo | 3 | Fractional resurfacing, dermatology clinic | PCE calibrated particle meter (0.30–10.00 μm) | ULPA filter, held at 1–3 inches | Er:YAG (2940 nm, fractional, coagulation mode) | Baseline : 8 PPS ± 6 Mean : 44 PPS ± 11 | 4 |
| Karveli et al, [ ] 2021 | Ex vivo | 2 | Dentin removal, dental clinic | Gravimetric air pumps | — | Er:YAG (2940 nm, pulse frequency 20 Hz, 200–400 mJ) | PM 2.5 μm increased by a factor of 10, PM 10 μm increased by a factor of 15 | 4 |
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