Evaluation of personal exposure to airborne pollutants in a middle-sized shipyard in Singapore

Abstract

Being a catalyst for Singapore’s economy, the marine and offshore (M & O) industry has flourished over the years with significant local and foreign labour employment. In addition to being a labor-intensive industry, similarities shared between the shipyard’s operations to construction and manufacturing works has raised concerns with regards to workers’ exposure to airborne pollutants.

Between 10th and 22nd January 2013, sampling for PM10, PM2.5 as well as Volatile Organic Compounds (VOCs) were thus conducted in the micro-environments of a shipyard located at the western part of Singapore to evaluate workers’ exposure to these airborne pollutants. In addition, concentrations of 9 metallic elements were also determined from the particulate matter (PM) samples that were collected from cyclones placed outdoor of a cargo container within the shipyard between 14th and 22nd January 2013. The assumption for this study will be that daily variations of a worker’s 8-hr work shift is slight which means that the results from short-term exposure assessment can be used to approximate a longer term exposure conditions.

The PM10 and PM2.5 concentrations in different work stations of the shipyard revealed significantly high contribution of particles in the PM2.5 size range with a ratio of 0.25 or higher and a positive correlation in linear regression analysis. The nature of work activities and conditions observed during sampling at the work station have suggested welding fumes and diesel-operated heavy-duty vehicles such as tower cranes and forklifts to be major contributors of the fine particulates. The measured PM10 and PM2.5 at majority of the work areas in the shipyard also exceeds the suggested standards stipulated by U.S. Environmental Protection Agency and World Health Organization (WHO). In addition, VOCs such as BTEX compounds and 1,2,4-Trimethylbenzene were also identified at work areas such as the main road and hull fitting workshop which indicated harmful exposures to both vehicular emissions and solvent usage during work. The results of heavy metal analysis also revealed major contributions from nickel, iron, lead and manganese in samples of PM2.5 which is in line with the SEM images obtained that much of the heavy metals are found in the finer particulates. This constitutes a health risk considering the toxicity of heavy metals as well as the deposition characteristics of the PM2.5 particles in human respiratory system.

Hence, the effects of these airborne pollutants to the health of the shipyard workers must be addressed as the pollutant levels measured in the study are indicative of harmful exposures.