Workplace performance of a loose-fitting powered air purifying respirator during nanoparticle synthesis

Antti J. Koivisto, Mikko Aromaa, Ismo K. Koponen, Wouter Fransman, Keld A. Jensen, Jyrki M. Mäkelä, Kaarle J. Hämeri

    Research output: Contribution to journalArticleScientificpeer-review

    18 Citations (Scopus)


    Nanoparticle (particles with diameter ≤100 nm) exposure is recognized as a potentially harmful size fraction for pulmonary particle exposure. During nanoparticle synthesis, the number concentrations in the process room may exceed 10 × 10<sup>6</sup> cm<sup>−3</sup>. During such conditions, it is essential that the occupants in the room wear highly reliable high-performance respirators to prevent inhalation exposure. Here we have studied the in-use program protection factor (PPF) of loose-fitting powered air purifying respirators, while workers were coating components with TiO<inf>2</inf> or Cu<inf>x</inf>O<inf>y</inf> nanoparticles under a hood using a liquid flame spray process. The PPF was measured using condensation particle counters, an electrical low pressure impactor, and diffusion chargers. The room particle concentrations varied from 4 × 10<sup>6</sup> to 40 × 10<sup>6</sup> cm<sup>−3</sup>, and the count median aerodynamic diameter ranged from 32 to 180 nm. Concentrations inside the respirator varied from 0.7 to 7.2 cm<sup>−3</sup>. However, on average, tidal breathing was assumed to increase the respirator concentration by 2.3 cm<sup>−3</sup>. The derived PPF exceeded 1.1 × 10<sup>6</sup>, which is more than 40 × 10<sup>3</sup> times the respirator assigned protection factor. We were unable to measure clear differences in the PPF of respirators with old and new filters, among two male and one female user, or assess most penetrating particle size. This study shows that the loose-fitting powered air purifying respirator provides very efficient protection against nanoparticle inhalation exposure if used properly.

    Original languageEnglish
    JournalJournal of Nanoparticle Research
    Issue number4
    Publication statusPublished - 9 Apr 2015
    Publication typeA1 Journal article-refereed


    • Aerosol
    • Air purifying respirator
    • Filtration
    • Occupational safety
    • Protection factor
    • Respirator performance

    Publication forum classification

    • Publication forum level 1

    ASJC Scopus subject areas

    • Atomic and Molecular Physics, and Optics
    • Condensed Matter Physics
    • Modelling and Simulation
    • General Chemistry
    • General Materials Science
    • Bioengineering


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