Continuous-flow air-supplied breathing apparatus with a visor is the
respiratory protective equipment (RPE) of choice within the motor vehicle
repair trade for protection against exposure to isocyanate paints. Whilst these
devices are capable of providing adequate protection, a common workplace
practice of sprayers lifting up the visor of their RPE immediately after
spraying when checking the quality of the paint finish is thought to have an
impact on the protection afforded. While the visor lift may be only for a few
seconds, this action, especially if repeated numerous times during a work
shift, could potentially result in a significant increase in exposure.

Informal interviews with paint sprayers were conducted to understand the
reasons for this behaviour followed by a series of laboratory tests to quantify
the potential degree of exposure as a result of a visor lift.

The majority of the paint sprayers interviewed explained their reasons for
lifting their visors immediately after spraying and before the spray booth had
been adequately cleared by ventilation. The main reasons given for a visor lift
included a combination of habit, poor visibility due to poor visual clarity of
the visor screen material, over spray, scratched visor screens, internal visor
reflections, and poor booth lighting.

The results of tests, published in the Annals of Occupational Hygiene, showed
that the degree of protection provided by the visor when in the lifted position
is in the approximate range of 1-3.7 (mean 1.7) and over the whole of the
exposure period (from start of the lift to recovery of protection after
refitting) is in the approximate range of 1.4-9.0 (mean 2.7). This is a
significant reduction when compared to the assigned protection factor of 40 for
this class of device and the measured protection factors of 5000-10 000 when
worn correctly.

These results clearly demonstrate that lifting the visor whilst still within a
contaminated atmosphere considerably increases the wearer's exposure and that
this is an example where improvements in RPE design can contribute to lower
exposure.

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AplusA-online.de - Source: The Annals of Occupational Hygiene