Noise surveys of hand-held pneumatic rock drills in Hong Kong

A study of the noise generated by hand-held pneumatic rock drills at 15 road works locations in Hong Kong was conducted in 1989. The locations of road construction works were identified over one week period. Sound pressure levels (SPL) and band frequency analysis were measured with the integrated sound level meter at the level of the operator's ears. The sound levels for all 15 operators exceeded the local statutory limit of 90 dBA. The average sound level was 107.4 dBA and the corresponding continuous equivalent level adjusted to 8 hours or L_eq (8h) was 104.8 dBA. The sound levels for the octave frequencies from 125 Hertz to 8000 Hertz were all in excess of 90 dBA. Estimates of the risk of developing hearing impairment for conversation speech among the operators were 18% and 42% after 5 and 10 years of exposure, respectively. Although there is adequate statutory control to restrict and reduce the hazards caused by noise at road construction works to the workers and to the public at large, no noise control measures were noted at the work sites and none of the operators used hearing protection. This situation was compounded by the short-term nature of road works and the high mobility of the operators.