Carbon monoxide exposure assessment among toll operators in Klang Valley, Kuala Lumpur, Malaysia

Abstract

A comparative cross-sectional study was conducted to determine tollbooth carbon monoxide (CO) levels and carboxyhaemoglobin (COHb) levels among the tollbooth operators and office workers in the Klang Valley, Kuala Lumpur. All tollbooths were equipped with well functioning air-conditioning. The total number of respondents was 180: 90 toll operators and 90 office workers aged between 19 and 52 years. The highest peak of CO level recorded was 61 ppm. The highest average peak CO level within a shift was 30 ppm. The CO level was higher during peak traffic at 6.00 – 8.00 a.m. There was no significant correlation between average peak CO level with vehicle load (r = −0.007, p = 0.474). The toll operators' median COHb level (1.0%, IQR = 0.8%) was significantly higher (p = 0.008) compared to office workers (0.7%, IQR = 0.8). There was a weak and significant correlation between COHb levels with average peak CO levels (r = 0.228, p = 0.031). In conclusion, tollbooth operators were chronically exposed to CO leading to higher COHb levels compared to office workers.

Keywords:

• Carbon monoxide
• carboxyhaemoglobin
• tollbooth operators
• vehicle load

Acknowledgements

The authors would like to acknowledge funding support of this work by the National University of Malaysia. They also express thanks to Forensic Unit, Chemistry Department, Petaling Jaya for giving training on COHb analysis and to Toll Concessionaires, volunteers who took part in the study and Professor Pakeer Oothuman Syed Ahamed who assisted in the writing of the paper.