An investigation of upper respiratory symptoms and related exposure to diesel exhaust emissions amongst employees at selected paint manufacturing industries within eThekwini, KwaZulu-Natal, South Africa

Abstract

Introduction: Diesel engines have high efficiency, durability, and reliability, together with their low-operating cost. These important features make them the most preferred engines for heavy-duty applications in agriculture, construction and industry. However, diesel engines are combustion engines and emit combustion products in their exhaust gas. Pollution emitted from diesel-operated vehicles are one of the largest preventable contributors to pollution caused by exhaust emissions, which are responsible for several health problems. The pollution produced by diesel-powered vehicles occurs significantly during idling and in the process of acceleration. Diesel particulate matter (DPM) is one of the concerning pollutants created from the combustion of diesel fuel due to the size of the particles and impacts they have on the respiratory system. Epidemiological studies have provided strong evidence for associations of DPM inhalation with inflammatory lung and cardiovascular diseases. In addition, DPM is classified as a human carcinogen by the International Agency for Research on Cancer. Methodology: The relationship between an employee’s upper respiratory symptoms and diesel exhaust emitted from forklift trucks was studied in two paint manufacturing companies located in eThekwini, KwaZulu-Natal, South Africa. The study population comprised 120 employees from both paint manufacturing companies. Data collection was conducted in two phases. The first phase entailed using a questionnaire as a data collection tool to establish Objective One of the research. The questionnaire was adapted to determine if there were any existing upper respiratory symptoms related to diesel exhaust emissions (DEE) being experienced amongst the exposed group of employees. The questionnaire consisted of three sections. Section A captured the participants’ biographical information such as name, age, gender, race, residential address, contact information and spoken home languages. Section B of the questionnaire captured the employees’ work history information. Section C captured information related to health issues of the employees. The second phase of the research entailed conducting personal air sampling. The purpose of the personal air sampling was to meet Objective 2 of the research, namely to quantify the level of diesel particulate matter employees were exposed to. Twenty-four personal air samples in total were taken from both paint manufacturing companies. The personal air sampling was conducted and analysed in accordance with the National Institute for Occupational Safety and Health (NIOSH) method 5040. The selection process for employees for the personal air sampling were based on their job function, source of pollution and exposure duration. Diesel powered forklift truck drivers were identified as the most exposed group of employee’s. Personal air sampling was conducted over an 8-hour period Results: The results of the questionnaire indicated that the ratio of males to females was approximately 4:1 (78.3%: 21.7%) (p < 0.001). None of the respondents indicated any shortness-of-breath issues. A small number (n = 2 or 1.7%) indicated that they sometimes experienced shortness of breath whilst doing work outside of their jobs (p < 0.001). However, some respondents did indicate that they coughed at their work stations (p < 0.001). Additionally, all of the respondents (n = 120) believed that exposure to diesel powered forklifts impacted their general health. According to the Hazardous Chemical Agents regulations of South Africa, an occupational exposure limit for DPM over an eight-hour time weighted average (TWA) of 0.16 mg/m3 was legislated. Twenty-four personal air samples were taken from the most exposed group of employees. Results of the personal air sampling indicate that DPM, measured as elemental carbon (EC), were below the occupational exposure limit of 0.16 mg/m3 for all samples taken. The results ranged between 0.004 mg/m3 and 0.011 mg/m3 . The results established that the most exposed group of employees, being the diesel-powered forklift truck drivers, were exposed to relatively low quantities of DPM. Conclusion: It was concluded that based on the results of the personal air sampling for DPM, the highest risk group of employees, namely the diesel-powered forklift truck drivers were exposed to relatively low levels of diesel particulate matter. This could be due to engineering controls in place such as the use of diesel particulate filters (DPF) on the diesel-powered forklift trucks, frequencies and duration of operating the diesel-powered forklift trucks and ventilation factors as the study setting was an above-ground study conducted in open warehouses. In addition, recommendations to further reduce the exposure to DPM were made in accordance with the hierarchy of control.