Work-related heat stress concerns in automotive industries: a case study from Chennai, India

Abstract

Background: Work-related heat stress assessments, the quantification of thermal loads and their physiological consequences have mostly been performed in non-tropical developed country settings. In many developing countries (many of which are also tropical), limited attempts have been made to create detailed job-exposure profiles for various sectors. We present here a case study from Chennai in southern India that illustrates the prevalence of work-related heat stress in multiple processes of automotive industries and the efficacy of relatively simple controls in reducing prevalence of the risk through longitudinal assessments.

Methods: We conducted workplace heat stress assessments in automotive and automotive parts manufacturing units according to the protocols recommended by NIOSH, USA. Sites for measurements included indoor locations with process-generated heat exposure, indoor locations without direct process-generated heat exposure and outdoor locations. Nearly 400 measurements of heat stress were made over a four-year period at more than 100 locations within eight units involved with automotive or automotive parts manufacturing in greater Chennai metropolitan area. In addition, cross-sectional measurements were made in select processes of glass manufacturing and textiles to estimate relative prevalence of heat stress.

Results: Results indicate that many processes even in organised large-scale industries have yet to control heat stress-related hazards adequately. Upwards of 28% of workers employed in multiple processes were at risk of heat stress-related health impairment in the sectors assessed. Implications of longitudinal baseline data for assessing efficacy of interventions as well as modelling potential future impacts from climate change (through contributions from worker health and productivity impairments consequent to increases in ambient temperature) are described.

Conclusions: The study re-emphasises the need for recognising heat stress as an important occupational health risk in both formal and informal sectors in India. Making available good baseline data is critical for estimating future impacts.

Keywords: WBGT; automotive industry; climate change; work-related heat stress.

Fig. 1.

Box plots illustrating the distribution of measured WBGT values at various indoor locations in automotive or automotive parts manufacturing units (dashed lines indicate the range of outdoor WBGT values across locations; dark boxes indicate locations with process-generated heat contributions and light boxes indicate locations without process heat contributions (i.e. only ambient temperature contributions), respectively, to heat stress. Work locations key: With process heat contributions – A: PTCS (varnishing oven), B: cab furnace, C: paint shop, D: fuel injection manufacturing, E: tube manufacturing, F: canteen (boiler area). Without process heat contributions – G: body shop (general shop floor), H: fuel injection manufacturing (general shop floor), I: paint shop (general shop floor), J: stamping, K: wheel alignment and engine deck, L: material storage and stores, M: PTCS (starter, armature and shaft areas), N: team meeting areas, O: plastic moulding area, P: utility areas, Q: canteen (general), R: brazing, S: trim and chassis.

Fig. 2.

Workloads at various locations in relation to WBGT indices (dark boxes indicate locations with process-generated heat contributions and light boxes indicate locations without process heat contributions (i.e. only ambient temperature contributions), respectively, to heat stress; dashed lines indicate TLV for fully acclimatised light work and dotted-dashed lines indicate TLV for fully acclimatised moderate work). Work locations key: With process heat contributions – A: PTCS (varnishing oven), B: cab furnace, C: paint shop, D: fuel injection manufacturing, E: tube manufacturing, F: canteen (boiler area). Without process heat contributions – G: body shop (general shop floor), H: fuel injection manufacturing (general shop floor), I: paint shop (general shop floor), J: stamping, K: wheel alignment and engine deck, L: material storage and stores, M: PTCS (starter, armature and shaft areas), N: team meeting areas, O: plastic moulding area, P: utility areas, Q: canteen (general), R: brazing, S: trim and chassis. Many locations with light workloads were still in excess of TLVs (indicating the need for engineering controls). Other locations with moderate workloads were close to or exceeded the TLVs (indicating opportunities for both administrative and engineering controls).