Occupational Heat Stress and Climate Change in Da Nang

Hot weather is recognized as detrimental to human health and labor productivity when temperatures and humidity exceed physiological thresholds. Occupational extreme heat exposure can lead to a number of detrimental heat-health impacts on workers. Excessive night-time temperatures following hot days do not allow for workers to recover and can compound work heat-health impacts. Climate change is projected to increase the number of hot days and nights, extend the length of the hot season and lead to a greater number of heat waves in many urban areas throughout Asia. As part of the Asian Cities Climate Change Resilience Network (ACCCRN) initiative, the Institute for Social and Environmental Transition (ISET) worked with the Centre for Community Health and Education (COHED) to see how climate change might change heat stress and stroke risk on the job in Da Nang, Vietnam. Healthy people can begin experiencing negative health impacts at ambient temperatures of 27°C and a relative humidity of 40%, but workers in jobs like construction, manufacturing, agriculture or mining can be exposed to even higher temperatures or physically demanding conditions at work. Despite the health risks, COHED found that few companies they interviewed knew of heat exposure risks or had protective measures in place.

Increasing awareness and helping companies develop heat exposure measures is particularly important. The Ministry of Health specifies that workplace protective measures need to be taken for workers engaged in heavy labor when temperature and humidity conditions create a heat index of 28°C, and 32°C for workers sitting at desks.

ISET calculated the heat index – a combination of temperature and humidity – in Da Nang and the number of days and nights between 1970-1999 that exceeded certain temperature limits. Using a number of climate models, ISET then investigated how many days and nights in the future (2020-2049) might exceed the limits because of climate change. By 2050, the daytime heat index exceeds the 32°C threshold nearly continuously between April and October. The number of nights exceeding 28°C is also expected to increase significantly, and workers without air conditioning at home may not be able to recover from the heat exposure while they sleep.

COHED is using this information as part of their workplace heat-health campaign with enterprises in Da Nang. COHED tested the heat index on three companies for ease of use to notify health and safety officers when unsafe heat exposure limits were being reached, and knowing when to trigger safety measures. The campaign is now being expanded to other enterprises throughout Da Nang.