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4. Results and discussion on the exposure measurements on the paving site
The exposure values (corrected for field blank) are given in Table 1. There are 8-hour
Time-Weighted Average values (TWA). The 8-hr TWA values correspond to average
exposure over the course of an 8-hour work shift. This value is often preferred
because it is more representative of a full workday.
Table 1
8 h TWA in mg/m 3 WAM laying (day 2)
MF BSF SV
Paver driver 0.22 0.05 3.45
Screedman 1 0.19 0.08 2.40
Screedman 2 0.19 0.07 1.18
Raker 0.16 0.14 2.93
Roller driver 0.13 0.03 0.79
Static 1 0.97 0.02 0.32
Static 2 0.14 0.01 0.23
The main part of the aerosols is inorganic (mineral dust). Relevant exposure data
(BSF) have been compared with Italian OELs. On an 8-hr Time-Weighted Average
basis, no measured values exceed these OELs.
It must be understood that in all cases (hot and warm production) the values
determined are well below any occupational exposure or environmental limit. This
clearly demonstrates that both hot mixture and WAM-Foam production are fully
acceptable from an occupational and environmental point of view.
When compared with Shell’s previous exposure measurements conducted on paving
HMA, these emissions are in the lower range (commonly 0.05-0.60 mg/m 3 in BSF).
The same level of magnitude (< 0.05) was previously recorded when using usual pen
grade binders (e.g. 35/50) at around 150°C.
The BSF data are also consistent with exposure data from our earlier studies (up to
0.05 mg/m 3 ).
Static values were found rather high especially in terms of mineral dust. This is
probably explained by the traffic on the other side of the motorway.
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