Worker Exposure Monitoring of Suspended Particles in a Thermal Spray Industry

Abstract

The purpose of the present work was the investigation and characterization of the quality of air in a thermal spray industry, in Greece. The activities that take place in the specific facility, as well as in most other similar industries, include thermal spraying and several mechanical and metallurgical tasks that generate airborne particles, such as grit-blasting, cutting and grinding of metallic components. Since the main focus of this work was the workers exposure to airborne particles and heavy metals, portable air samplers with quartz fiber filters, were used daily for 8 h. Three samplers, carried from different employees, were used for a period of 1 month. Results showed that both particles and heavy metals concentrations were low, even in the production site, which was the most susceptible area. The only exceptions were observed in the case of cleaning and maintenance activities in the thermal spray booth and in the case of spraying outside the booth. The main reason for the low concentrations is the fact that most of the activities that could produce high-particle concentrations are conducted in closed, wellventilated systems. Statistical elaboration of results showed that particles are correlated with Ni, Cu, Co. The same conclusion is extracted for Fe, Mn. These correlations indicate possible common sources.

Modeling of High Nanoparticle Exposure in an Indoor Industrial Scenario with a One-Box Model

“…From a risk assessment perspective, thermal spraying is known to generate unintentional nanoparticle (NP) emissions (with diameters < 100 nm; 10 6 cm −3 ) at pilot-plant and industrial scales [6,7]. High particle mass concentrations have also been reported [8,9]. Similar NP emission and formation mechanisms have been identified in a large variety of industrial processes [10,11,12,13,14,15,16,17].…”

Review of the physicochemical properties and associated health effects of aerosols generated during thermal spray coating processes

“…Because of the high particle number, the aerosols were observed by Bemer et al (2010) to be highly unstable due to coagulation, and the physical properties of the aerosol changed quickly during transport from the generation point to the sampling device. Similar observations have been demonstrated with welding fume as their physical characteristics have been shown to dynamically change based on time after particle formation (Zimmer and Biswas, 2001) as well as selection of processes and settings (Petsas et al, 2007). During thermal spray coating, Bemer and colleagues (2010) observed the aerosol using an electrical lowpressure impactor and condensation nucleus counter to be mostly in the submicron size range with 85-90% of the particles less than 100 nm.…”

“…In assessment of air quality in a thermal spray facility in Greece, portable air samplers using quartz fiber filters worn by workers for 8 h day −1 for 30 working days (not including weekends) indicated that total particle and specific metal concentrations were below the established Greek workplace limit of 10 mg m −3 for an 8 h day −1 (Petsas et al, 2007). The investigators believed this was most likely because of work using closed and well-ventilated systems.…”

“…Elevated urinary concentrations of chromium, nickel, and cobalt in workers during thermal spray coating processes Chadwick et al (1997) Worker death due to severe lung damage caused by toxic metal inhalation during thermal spray coating Washington State Department of Labor and Industries (2005) Elevated particle concentrations were observed during cleaning and maintenance activities in a thermal spray coating booth Petsas et al (2007) Emission rates for thermal spray coating process far exceeded those compared to arc welding Bemer et al (2010) Total dust concentrations during spray coating exceeded local exposure limits by four to eight times Huang et al (2016) Elevated ultrafine particle formation was observed inside and outside spray coating chamber Viana et al (2017) Ninety percentage of particles formed during spray coating processes were less than 90 nm Salmatonidis et al (2019Salmatonidis et al ( , 2020…”