Table 5 Studies focused on the particle release of ENMs by laboratory testing (column 1 indicates the different subcategorisations)

Powders

[53]

Rotating drum test (free fall, stirring, ...)

TiO₂ (Aeroxide P25), ZnO

SMPS, APS, MOUDI

PSD (15 nm - 20 μm), NC, DI

< 10% particles < 100 nm60% particles < 1 μm

[65]

Rotating drum test (free fall, stirring, ...)

TiO₂, SiO₂, FeO(OH), Mg₃Si₄O₁₀(OH)₂, Al₂O₃

FMPS, APS, Filtration

PSD (5.6 nm - 20 μm), NRP (0.5 μm - 20 μm), NRP (5.6 nm - 560 nm), DI

Undefined fraction of particles < 100 nm

[66]

Rotating drum test (free fall, stirring, ...)

Organoclay, Bentonite

FMPS, APS, Filtration

PSD (5.6 nm-20 μm), NRP (0.5 μm - 20 μm), NRP (5.6 nm - 560 nm), DI

Undefined fraction of particles < 100 nm

[70]

Free fall

TiO₂ (G5), SiO₂ (Aerosil 200)

ELPI; SEM (ELPI)

PSD(30 nm - 10 μm), MC, MC/M

Fraction of particles < 100 nm

[71]

Fluidized bed

TiO₂ (Aeroxide P25)

SMPS (LDMA, NDMA), APS; TEM (ESP)

PSD (4 nm - 20 μm)/NC_max

10% particles < 100 nm

70% particles < 1 μm

[4, 72]

Vortex shaker (fluidized bed, agitation)

SWCNT, alumina powder

SMPS (LDMA, NDMA), APS

PSD (4 nm - 20 μm), NC

Fraction of particles < 100 nm, alumina powder released more NP than SWCNT

[73]

Vortex shaker (fluidized bed)

SWCNT, MWCNT, TiO₂, ZnO

SMPS, HHCPC, APS, OPC

PSD (10 nm - 20 μm), NC (10 nm - > 1 μm)/V, NC (10 nm - > 1 μm)/M

Fraction of particles < 100 nm

[74]

Shaker method

MWCNT

SMPS, APS, TEM(ESP, CI)

PSD (14 nm - 20 μm), NC(dt)

Fraction of particles < 100 nm;

peak at 200-300 nm

[75]

Fluidized bed with oscillating sieve plate

MWCNT

SMPS, SEM (TP)

PSD (< 1 μm), NC(dt)

Fraction of particles < 100 nm

[29]

Stirring and dispersing in orifice (leak in pressurized vessel)

TiO₂, CeO₂, SrCO₃, TiZrAlO

SMPS

PSD (14 nm - 736 nm), fractions, relative values

Increase of the fraction of ENPs by increase of the overpressure (up to 12%)

Suspensions

[38]

Weighing/transferring of powders and sonication of suspensions

fullerenes, MWCNT, CB

HHCPC, HHPC, TEM-EDX (filtration)

PSD (0,3 μm - 10 μm), NC (10 nm - 1 μm)

Suspension sonication leads to droplets with embedded ENM

[77]

Spraying

suspensions with and without Ag

SMPS, TEM(ESP)

PSD (10 nm - 500 nm), NC (< 100 nm), NC(< 500 nm)

High fraction of particles < 100 nm

Coatings

[63]

Weak abrasion process (Taber Abraser)

PVC layer with/without ENPs (nanoclay)

SMPS, CPC

PSD (5 nm-1 μm)

[64]

Weak abrasion process (Taber Abraser)

coatings with/without ENPs (ZnO)

SMPS, CPC; SEM/TEM-EDX (ESP)

PSD (16 nm - 626 nm), NC (> 6 nm), wear mass

Very low concentrations, ENPs still embedded

[81]

UV light, wind erosion, scrabing

coatings with TiO₂

SMPS

PSD (15 nm - 661 nm), NC (15 nm - 661 nm)

Comparison with non-doped samples is missing

[54]

Shaving (razor blade)

CNT

FMPS, HHCPC, SEM & TEM - EDX (TP)

NC (10 nm -1 μm), PSD (5.6 nm-560 nm)

No significant change in concentration; no free CNTs were observed

[7, 8]

Sanding process (orbital sander)

coatings with/without ENPs (TiO₂, CB, SiO₂, CaCO₃)

FMPS, APS(ESP)

PSD (5.6 nm-20 μm)

General release of NP, spark particles contamination

[67]

Sanding process (Dremel)

coatings with/without ENPs (ZnO, Fe₂O₃)

FMPS, CPC, OPCSEM/TEM-EDX (ESP)

PSD (5.6 nm-20 μm), NC (< 100 nm), NRP (< 100 nm), NRP (< 10 μm), swarf mass; material, morphology

General release of NP but ENPs still embedded in the matrix

Composites

[82]

UV-light; weak abrasion process (Taber Abraser); customized sanding

POM with/without CNT, PA with/without SiO₂, cement with/without CNT, cement with/without CSH

SMPS, UNPA, SEM, AUC, XPS, SIMS

PSD (14 nm-820 nm), Morphologie, material

No free SiO₂-particles or CNTs detected

[42]

Dry and wet cutting (band-saw; rotatory cutting wheel)

composites with and without CNT

FMPS, APS, HHCPC, DT, SEM/TEM-EDX (ESP, TP)

PSD (5.6 nm-20 μm), NC (5.6 nm - 560 nm),

NC (0.5 μm - 20 μm) MC, material, morphology

No free CNTs observed

[69]

Dry and wet solid core drilling

Composites with and without CNT

FMPS, APS, HHCPC, DT, DC, SEM/TEM-EDX (ESP, TP) WRASS+ICP-MS

PSD (5.6 nm-20 μm), NC, MC (< 35 μm), SA; material; morphology

Smoke generation, free CNT clusters observed