A new bivariate respirator fit test panel representing Black South African respirator users

Filtering facepiece respirators (FFRs) manufactured in South Africa and elsewhere for use by South African workers are commonly tested against non-South African respirator fit test panels (RFTPs) such as those for the United States and the Chinese population, the 2009 Chinese RFTP. These RFTPs are based on facial measurements of their respective populations. Our study evaluated the applicability of these panels to Black South Africans and developed a representative panel for Black South African respirator users.

Facial dimensions were collected from 693 Black South African respirator users using traditional anthropometric tools. Face width and Face length were overlaid on the NIOSH and Chinese bivariate RFTPs to determine their applicability by checking distribution within the panels and individual cells. We then developed a dedicated Black South African bivariate panel. This included adjustments of panel boundaries to contain 95% of the study population. Data were analysed using STATA version 17 (and graphed using Microsoft Excel).

Panels developed for the United States and Chinese populations did not adequately represent Black South Africans. Most (96.5%) of Black South Africans fell within the NIOSH panel, however, there was no uniform distribution. The Chinese panel only contained 90.8% within the cell boundaries, which was less than the required 95% population within the panel boundaries. Thus, a new bivariate panel representative of Black South Africans was developed. The new panel boundary limits for the Black South African panel are 95 to 135 mm for face length and 123 and 154 mm for face width, which differ from those of the NIOSH and Chinese panels. The final Black South African bivariate panel contains more than 97% of the study population with a more even distribution of subjects within the cell and panel boundaries.

The findings showed that the NIOSH and Chinese bivariate panels do not adequately represent the Black South African population. Respirators designed and tested using these panels or similar ones may negatively affect the desired fit of a Black South African population. The newly developed bivariate panel for Black South Africans should be validated in future studies. It is uncertain to what extent the findings are generalizable to the South and Southern African population external to the study area of Gauteng.