Occupational exposure to crystalline silica in artificial stone processing

Figures & data

Table 1. Characteristic of the facilities involved in the study.

Facility	Total no. of employees	Working material	Manual finishing			Mechanical processing
			Engineering controls	Type of processing	Adopted PPE*	Engineering controls	Type of processing	Adopted PPE
A	6	quartz-resin stones	extraction wall booths	dry	FFP3 face mask	water spraying equipment	wet	FFP3 face mask
B	15	quartz-resin stones	aspirated benches (perimeter)	dry	FFP3 face mask	water spraying equipment	wet	FFP3 face mask
C	65	quartz-resin stones	extraction wall booths	wet and dry	FFP3 face mask or half face mask with P3 filter	water spraying equipment	wet	FFP3 face mask or half face mask with P3 filter
D	14	ceramic products	aspirated benches (perimeter and wall) and one extraction wall booth	dry	FFP3 face mask	water spraying equipment	wet	FFP3 face mask

PPE = Personal Protective Equipment

Table 2. Levels of airborne respirable dust and RCS exposure in facilities involved in the study.

Facility	Respirable dust (mg/m^3)			RCS (mg/m^3)
	Mean ± SD	Median	Range	Mean ± SD	Median	Range
A (n = 4)	0.359 ± 0.430	0.171	0.098–0.996	0.046 ± 0.048	0.041	<0.005–0.098
B (n = 9)	0.071 ± 0.020	0.066^A^,B,C	0.059–0.124	0.007 ± 0.003	0.007^D^,E	0.004–0.011
C (n = 29)	0.098 ± 0.045	0.086	0.046–0.252	0.021 ± 0.020	0.014	<0.003–0.098
D (n = 9)	0.361 ± 0.322	0.232	0.120–1.154	0.027 ± 0.024	0.020	0.012–0.088
Total (n = 51)	0.160 ± 0.207	0.092	0.046–1.154	0.022 ± 0.023	0.013	<0.003–0.098

^Ap = 0.0112 Facility B vs. Facility A, Mann-Whitney test

^Bp = 0.023 Facility B vs. Facility C, Mann-Whitney test

^Cp < 0.0001 Facility B vs. Facility D, Mann-Whitney test

^Dp = 0.0007 Facility B vs. Facility C, Mann-Whitney test

^Ep < 0.0001 Facility B vs. Facility D, Mann-Whitney test

n = sample size

SD = Standard Deviation

Table 3. Levels of airborne respirable dust and RCS exposure categorized by type of working process.

Job task	Respirable dust (mg/m^3)			RCS (mg/m^3)
	Mean ± SD	Median	Range	Mean ± SD	Median	Range
Manual finishing (n = 22)	0.229 ± 0.299	0.100	0.048–1.154	0.030 ± 0.031	0.017^A^,B	0.004–0.098
Mechanical processing (n = 25)	0.109 ± 0.055	0.092	0.046–0.245	0.016 ± 0.013	0.012	0.004–0.054
Other (bonding, packaging, warehouse management) (n = 4)	0.102 ± 0.049	0.094	0.052–0.168	0.009 ± 0.007	0.007	<0.003–0.018

^Ap = 0.047 Manual finishing vs. Mechanical processing, Mann-Whitney test

^Bp = 0.03 Manual finishing vs. Other activities, Mann-Whitney test

n = sample size

SD = Standard Deviation

Table 4. Levels of airborne respirable dust and RCS exposure categorized by method of manual finishing.

Manual Finishing	Respirable dust (mg/m^3)			RCS (mg/m^3)
	Mean ± SD	Median	Range	Mean ± SD	Median	Range
Dry (n = 12)	0.352 ± 0.366	0.230^A	0.063–1.154	0.039 ± 0.038	0.020	0.004–0.098
Wet (n = 10)	0.082 ± 0.027	0.077	0.048–0.141	0.020 ± 0.014	0.016	0.009–0.054

^Ap = 0.0216 Dry vs. Wet, Mann-Whitney test

n = sample size

SD = Standard Deviation

Figure 1. Correlation between respirable dust and RCS content in the facility where quartz-resin (a) or ceramic (b) material were used.

Figure 2. Aspirated benches in facility B (panel a) and facility D (panel b).

Data availability statement

The authors confirm that the data supporting the findings of this study are available within the article.