Table 2

Impinger to PCM conversion estimates using paired and concurrent samples

Study plant IDExposure zone groupPaired samples (n)Concurrent samples (n)Paired samplesConcurrent samplesCombined estimates
PCM/imp ratio*95% LCL95% UCLPCM/imp ratio95% LCL95% UCLPCM/imp ratio95% LCL95% UCL
1Prep-card12405.243.317.604.453.286.034.774.165.37
1Spin-twist12583.091.824.692.471.513.852.732.203.27
1Weave-product7522.630.237.601.520.882.451.600.422.78
3Prep-card301493.842.645.258.786.9910.885.524.956.09
3Spin-twist401311.540.922.314.523.276.072.602.133.07
3Weave-product46756.404.468.715.663.159.626.165.426.89
4Prep-card15858.726.2511.597.235.269.718.047.378.71
4Spin-twist18808.486.5710.734.903.376.817.026.467.58
4Weave-product271209.167.2011.354.323.245.726.986.477.49
  • *PCM fibres>5 μm/ml per MPPCF.

  • Imp, impinger; LCL, lower confidence limit; MPPCF, millions of particles per cubic foot of air; PCM, phase contract microscopy; UCL, upper confidence limit.