Page 112 - Engineering Rock Mass Classification_ Tunnelling, Foundations and Landslides

Tunnel—Cont’d Physiological effect on workers
el exhaust and
el exhaust and Strongly irritating to mucous membranes at
low concentrations; can be kept below
objectionable levels by limiting fuel sulfur
content to 0.5%

NO2 is most toxic; all oxides of nitrogen cause
severe irritation of the respiratory tract at high
concentrations; acute effects may be followed
by death in a few days to several weeks owing
to permanent lung damage