Interlaboratory comparison of particle filtration efficiency testing equipment.

Particle filtration efficiency (PFE) is a critical property of face masks, with the most common test methods using sodium chloride as a challenge aerosol. In the absence of bottom-up uncertainty budgets for PFE, interlaboratory comparisons provide an alternative route to robustly quantify the precision and bias of the method. This work presents the results of several interlaboratory comparisons of particle filtration efficiency performed across a network of laboratories.

Particle filtration efficiency measured using sodium chloride and polystyrene latex sphere test methods.

Standards governing face masks differ in the test methods used to determine sub-micron particle filtration efficiency (PFE), such that the meaning of PFE is not universal. Unifying the meaning of PFE requires data using these different test methods to drive improvements in standards. This simple data set provides the equivalence between two major test methods used to assess PFE: (1) a test method using a neutralized, polydisperse sodium chloride (NaCl) and (2) a test method using an unneutralized, "monodisperse" polystyrene latex sphere (PSL) aerosols.

Comparison of measurement systems for assessing number- and mass-based particle filtration efficiency.

The particle filtration efficiency (PFE) of a respirator or face mask is one of its key properties. While the physics of particle filtration results in the PFE being size-dependent, measurement standards are specified using a single, integrated PFE, for simplicity. This integrated PFE is commonly defined concerning either the number (NPFE) or mass (MPFE) distribution of particles as a function of size.

Laser-induced incandescence for non-soot nanoparticles: recent trends and current challenges.

Laser-induced incandescence (LII) is a widely used combustion diagnostic for in situ measurements of soot primary particle sizes and volume fractions in flames, exhaust gases, and the atmosphere. Increasingly, however, it is applied to characterize engineered nanomaterials, driven by the increasing industrial relevance of these materials and the fundamental scientific insights that may be obtained from these measurements. This review describes the state of the art as well as open research challenges and new opportunities that arise from LII measurements on non-soot nanoparticles.