LIBS Illuminates the Hidden Health Risks of Indoor Welding and Soldering

A welder in protective gear fuses aluminum pieces with precision, © 69-chronicles-stock.adobe.com

A Breath of Fresh (or Not So Fresh) Air

As electronics manufacturing, repair, and small-scale welding become more common in indoor environments, the need to monitor what’s really in the air we breathe has never been more pressing. Recent studies by scientists in China shine a literal laser on the microscopic dangers floating in these enclosed spaces, particularly focusing on pollutants emitted during soldering and welding activities.

Using laser-induced breakdown spectroscopy (LIBS) and single-particle aerosol mass spectrometry (SPAMS), two complementary spectroscopic techniques, researchers have developed a rapid, real-time detection platform that identifies and tracks harmful airborne particles—especially heavy metals like lead (Pb) and tin (Sn), as well as carbon emissions and fine particulate matter (PM) (1,2).

LIBS + SPAMS: A Dual-Tech Air Quality Solution

In a 2025 study published in Spectrochimica Acta, Part B: Atomic Spectroscopy, researchers Nuerbiye Aizezi, Yanpeng Ye, Ziang Chen, and Yuzhu Liu from Nanjing University of Information Science & Technology used LIBS to directly monitor emissions from soldering operations. LIBS employs a high-energy Q-switched Nd: YAG laser (1064 nm) to create a plasma on airborne particles, producing emission lines that reveal the elements present—no sample prep required (1,2).

In an earlier complementary study published in Optics and Lasers in Engineering, Enlai Wan, Qihang Zhang, Lei Li, Qinhui Xie, Xuan Li, and again Yuzhu Liu combined LIBS with SPAMS to provide additional data such as isotopic composition and particle size distribution, offering a richer profile of the pollutants and their potential health impacts (2).

Together, these tools form a real-time monitoring system capable of assessing the nature, origin, and concentration of harmful aerosols, and were deployed to compare emissions from traditional lead-tin solder wire versus lead-free alternatives.

Temperature, Toxins, and Time

One of the most striking findings from Aizezi and colleagues was the clear link between soldering temperature and pollutant levels. LIBS revealed that as the soldering temperature rose, the evaporation rates of Pb and Sn increased sharply. The carbon spectral line intensity also rose, indicating elevated gaseous emissions, possibly from flux combustion or organic material degradation (1).

Fine particulate matter < 2.5 µm (PM2.5) and < 10 µm (PM10) showed significant increases at higher temperatures. Notably, PM2.5 took longer to reach peak concentration in workers’ breathing zones, suggesting prolonged exposure to the most dangerous particles. PM2.5 is well-known for its ability to penetrate deep into the lungs and enter the bloodstream (1).

Quantitative analysis reinforced the observational data: Pearson’s correlation coefficients for Pb and Sn exceeded 0.8, and principal component analysis (PCA) analysis returned an R² of 0.89, confirming a strong linear relationship between temperature and pollutant intensity (1).

The Human Factor: Why Indoor Air Matters

As the second study points out, people now spend over 70–90% of their time indoors, making indoor air quality more important than ever—especially in workplaces where electronics or metal fabrication is performed. Exposure to Pb and Sn fumes can cause immune suppression,respiratory inflammation, and long-term neurological damage, with children and elderly populations particularly at risk (2).

The combination of LIBS and SPAMS allows for the classification of different welding emissions using machine learning (ML), including principal component analysis (PCA) and back-propagationartificial neural networks (BP-ANN), which could pave the way for AI-based indoor pollution alerts (2).

Cleaner Air Through Smarter Monitoring

This research, conducted across two state-of-the-art Chinese research hubs—the State Key Laboratory Cultivation Base of Atmospheric Optoelectronic Detection and Information Fusion and the Jiangsu International Joint Laboratory on Meteorological Photonics and Optoelectronic Detection at Nanjing University of Information Science & Technology—underscores a critical shift in environmental monitoring: speed, accuracy, and real-time insight (1,2).

Compared with conventional tools like ion chromatography or X-ray fluorescence, the LIBS-SPAMS combo is faster, non-destructive, and more adaptable to evolving conditions (2,3).

As soldering and welding remain integral to industries and DIY hobbies alike, this work provides both a warning and a roadmap. By making the invisible visible, these tools offer a path to cleaner indoor air and safer work environments.

References

(1) Aizezi, N.; Ye, Y.; Chen, Z.; Liu, Y. Impact of Soldering Temperatures on Heavy Metal and Dust Emissions: A LIBS-Based Environmental Pollution Analysis. Spectrochim. Acta, Part B 2025, in press, 107124. DOI: 10.1016/j.sab.2025.107124

(2) Wan, E.; Zhang, Q.; Li, L.; Xie, Q.; Li, X.; Liu, Y. The Online In Situ Detection of Indoor Air Pollution via Laser-Induced Breakdown Spectroscopy and Single Particle Aerosol Mass Spectrometer Technology. Opt. Lasers Eng. 2024, 174, 107974. DOI: 10.1016/j.optlaseng.2023.107974

(3) Wetzel, W. Evaluating the Impact of ICP-MS and LIBS on Environmental Monitoring. 2024, September 23. https://www.spectroscopyonline.com/view/evaluating-the-impact-of-icp-ms-and-libs-on-environmental-monitoring (accessed 2025-04-18)