Extreme temperatures due to global warming are impacting negatively on the general population in many regions of the world, yet heat-related illnesses remain largely overlooked. Heat-related morbidity and mortality is predicted to increase because of climate change. Environmental heat is emerging as a key public health issue, particularly amongst poor and vulnerable sectors of society in developing countries. This study assessed the exposure of outdoor street vendors in Bulawayo, Zimbabwe, to extreme heat whilst working between seven-and thirteen-hour shifts per day and mostly in direct sunlight during summer months. This group of workers is particularly vulnerable to heat-related and other health problems as they are deemed to be illegal traders and operate without the support of a legislative framework to monitor their health and wellbeing. With the current political upheaval in Zimbabwe there is an urgent need for government to develop heat prevention policies, heat prevention guidance measures and extensive programs for outdoor workers to increase their knowledge and awareness of the issue. It is also necessary to develop adaptation and coping mechanisms amongst this vulnerable sector of society, while also exploring other preventive measures that could reduce heat exposure more broadly.
Global warming due to climate change is a topical issue, with average surface temperatures projected to rise by between 1.8-4.0°C by the year 2100 worldwide [1]. As a result, various environmental health hazards and health-related issues including heat-related illnesses will emerge as public health problems in the future, particularly in developing countries, including the Southern Development Community (SADC) [2]. The impact of climate change and associated heat events on economically disadvantaged groups, particularly in developing countries, needs to be assessed and mitigation strategies must be developed to protect people and alleviate suffering of vulnerable groups, such as those engaged in low-paid jobs and working outdoors [3,4].
The frequency of extreme heat waves has been increasing, leading to excess morbidity and mortality, particularly in developing countries [5]. The burden of heat-stress-related illness is predicted to rise due to climate change effects [6-8]. People of low socio-economic backgrounds, outdoor street vendors and those with cardiovascular, respiratory and cerebrovascular diseases are deemed most vulnerable to the effects of heat waves [3]. In developing countries, the effects are more pronounced as there is a general lack of understanding of heat-related risks and communities generally have poor adaptive capacity, largely due to their inability to gain access to electricity and air conditioning [9].
Outdoor street vendors in developing countries, including in the city of Bulawayo in Zimbabwe, comprise a group of occupations that involve spending extended hours exposed to high temperatures and radiant heat without cooling sources or adaptation measures. In addition to the well-documented effects of heat stress such as heat cramps, heat syncope, heat exhaustion, heat stroke and mortality, this cohort will experience these effects in the future [4,10,11]. There are many more sinister health effects associated with chronic heat exposure and dehydration, particularly kidney disease, which impacts negatively on those exposed to heat [12]. In developing countries such mortalities may be misdiagnosed or not recorded due to lack of knowledge amongst health professionals and the population [2].
Studies have shown that hot summer temperatures in Zimbabwe from 1955 to 2003 increased by 1.86°C per decade [13]. Bulawayo, the second-largest city in Zimbabwe, has a sub-tropical climate with semi-arid hot summer temperatures averaging 29°C, however, the recent summers have been much hotter. During 2015, the city experienced two weeks of heat events-one in October and the other in November-withaverage daily temperatures of 32°C and some days reaching 40°C. These temperatures were accompanied by high humidity levels [2].
Bulawayo was the principal industrial hub of Zimbabwe in 1980’s, however, due to the country’s economic meltdown most industries closed, leaving over 130,000 economically active people working outdoors as street vendors, selling new and second-hand clothes, fruits and vegetables [14]. This cohort of workers is particularly susceptible to heat exposure as the city environment is also impacted by the urban heat-island effect [8]. Working long hours suggests that these people could potentially be suffering from the effects of heat stress.
The most critical factors in determining levels of heat-stress risk include: metabolic workload, average temperature of the surrounding area, humidity and air circulation [15]. Outdoor street vendors do not have high metabolic workloads for most of the day as they are usually seated or standing near their stalls. The physically demanding part of their work would be experienced when transporting their wares to and from their place of business; however, this occurs during the cooler part of the day. Although their work would be described as sedentary, they are generally seated in direct sunlight for many hours exposed to high temperatures and humidity without protection. These workers are also at risk of suffering dehydration due to sweating and lack of access to adequate clean water. These conditions can cause chronic health problems that may affect kidney function [7].
The dilemma of outdoor workers is further exacerbated by the fact that most of the exposed population live in inadequate housing and have no access to cool resting environments. Some people have no access to electricity, nor would they be able to afford air conditioning if they had electricity [4,10,16-18]. It is therefore anticipated that an increase in the frequency of heat waves will impact significantly on this vulnerable sector of society in the future [19].
To prevent heat-related illnesses, people employed in outdoor occupations, health professionals and policy makers should have adequate knowledge about the public health impacts of heat and the development of heat prevention strategies. In developing countries, capacity-building across the board can enhance peoples’ adaptation methods to the impacts of heat, thus reducing heat-related morbidity and mortality. From a government perspective it is necessary to recognise these “informal” illegal street vendors, who represent an extremely vulnerable sector of society and implement interventions such as provision of shade and cool potable water as well as health-promotion actions directed at building resilience and coping strategies as well as informing vendors when and how to seek early medical attention should it be required [8,20].
In developed countries, strict labour legislation guidelines regulate work in extreme heat and there are defined adaptation strategies that protect workers [17]. However, in most developing countries such as Zimbabwe, there is lack of public awareness and policy considerations regarding heat exposure [8,21]. Management of heat stress requires a consultative approach with all stakeholders to make decisions that may influence policy changes towards minimizing the hazard. According to Huang et al., [20], developing countries should include adaptive capacity building and adaptation implementation engagements to minimize heat stress. Preventive measures to reduce morbidity and mortality of workers associated with heat stress in developing countries may include early heatwave warnings, health promotion and improved working areas, including provision of adequate shade and ventilation, as well as access to cool sources of hydration. Organized land use and improved design plans of buildings, air conditioning use and adjustment to conditions are significant in prevention of heat effects [11,20]. However, in developing countries some of these strategies may not apply due to socioeconomic factors. There is lack of studies in developing countries, in particular the SADC, on monitoring heat effects on people and developing adaptation strategies to protect them.
Hazard Type |
Assessment Point Value |
|||
0 |
1 |
2 |
3 |
|
Sun exposure |
Indoors ? |
Shade ? |
Part shade ? |
No shade ? |
Hot surfaces |
Neutral ? |
Warm on contact ? |
Hot on contact ? |
Burn on Contact ? |
Exposed period |
< 30 min ? |
30 min-1 hour ? |
1 hour-2 hours ? |
>2 hours ? |
Confined space |
No ? |
Yes ? |
||
Task complexity |
Simple ? |
Moderate ? |
Complex ? |
|
Climbing, up/down stairs or ladders |
None ? |
One level ? |
Two levels ? |
?Two levels ? |
Distance from cool rest area |
? 10 metres ? |
? 50 metres ? |
50-100 metres ? |
?100 metres ? |
Clothing (permeable) |
Single layer (light) ? |
Single layer (moderate) ? |
Multiple layer ? |
|
Understanding of heat strain risk |
Training given ? |
No training given ? |
||
Air movement |
Strong ? |
Moderate wind ? |
Light wind ? |
No wind ? |
Respiratory protection-negative pressure |
None ? |
Disposable half face ? |
Rubber half face ? |
Full Face ? |
Acclimatisation |
Acclimatised ? |
Unacclimatised ? |
||
2 |
4 |
9 |
||
Sub-total A |
15 |
2 |
3 |
6 |
|
Metabolic work rate |
Light ? |
Moderate ? |
Heavy ? |
Sub-total B |
2 |
1 |
2 |
3 |
4 |
|
Apparent temperature |
? 27°C ? |
? 27°C ≤ 33°C ? |
? 33°C ≤ 41°C ? |
? 41°C ? |
Sub-total C |
2 |
The economic situation in Zimbabwe and many other developing countries has driven a large sector of the population to engage in informal outdoor employment. These workers do not receive legislative protection as their operations are perceived to be illegal and this extremely poor and vulnerable sector of society is at risk of suffering short-or long-term ill-health effects associated with heat waves [24].
These risks are further aggravated by the effects of climate change that have impacted the agro-based economies of developing countries. Droughts and floods have driven rural populations into the already congested cities such as Bulawayo, where industries have also closed, forcing the population to work informally in the city’s streets. Outdoor street vendors are exposed to environmental and occupational hazards during their daily activities. Heat stress adaptation in humans involves physiological adaptations, referred to as heat acclimatisation. It is assumed that these street vendors are fully acclimatised from working under such conditions in Bulawayo, as many had been in this current profession for several years.
Other heat adaptations observed includes actions taken to avoid heat exposure and to gain protection from extreme temperatures, direct sunlight and humid conditions. In a developed-world context, this is easier to achieve where most people are able to work in air-conditioned environments or have cooling options readily available. However, for illegal, informal traders on the streets of Bulawayo, this is clearly not an option. Additional measures may include the intake of sufficient fluids, being physically fit and active and having a well-balanced diet.
The public health dilemma is that most outdoor street vendors in Zimbabwe conduct their business in the open and in direct sunlight. Due to the impact of climate change, the summer months in Bulawayo have become hotter, with high humidity levels. This study demonstrated that street vendors are exposed to heat-stress risks, which are exacerbated by long work shifts of between seven to thirteen hours, often in direct sunlight and without protective measures against the heat. Sources of potable drinking water are not easily accessible to these workers as they are illegal vendors working in undesignated areas and have no access to the formal infrastructure in the city. Their monthly income levels range from less than $50 to $300 and they therefore cannot afford to buy drinking water on daily basis, thus exposing them to risk of dehydration. Their working conditions are generally not conducive to good health. In addition to having to cope with extreme heat in the summer, they are also exposed to air pollution from dust and vehicle emissions, which create further public-health problems.
This study shows that temperature levels and heat events have become more common and cause suffering and sickness amongst street vendors, who are deemed to be a particularly vulnerable group. Street vendors operate in the informal sector and their activities are deemed illegal, thus they do not benefit from government interventions and have no legal protection and have limited capacity to access healthcare. The group has limited choices to mitigate the effects of heat wave conditions, as they spend long hours under direct sunlight and most do not have access to electricity or effective means of cooling either at work or at home. The study shows that street vendors suffer from various heat-related symptoms such as headaches, dizziness, muscular aches, elevated body temperatures and insomnia during the summer, which is a clear indicator of heat-stress risk. There is lack of knowledge about heat-related illnesses including heat stress amongst this cohort and they do not seek medical help as most cannot afford it. The majority treat themselves and lacks an understanding about the short- and long-term health effects associated with heat exposure.
Some street vendors have implemented basic adaptive practices, other than acclimatisation, such as wearing light, loose clothing and hats during summer and seeking shade to rest in; some go as far as constructing illegal shelters using cardboard, canvas and plastic.
In addressing this public health dilemma, the government should establish heat-prevention policies to protect the health and safety of outdoor workers. The authorities should develop a comprehensive heat-prevention model that includes all stakeholders, such as government departments, health professionals and the street vendors. The Ministry of Health should be responsible for public health research, health promotion, monitoring, assessments and the provision of environmental health management services and healthcare provision aimed at developing and strengthening adaptation and coping strategies of heat-related consequences. Technical capacity building should involve provision of guidance materials that increase knowledge among health providers in recognising the risks associated with heat exposure and treating and advising vulnerable communities on heat-related public health effects. Local governments such as Bulawayo should allocate resources to plan, design, develop and provide infrastructure that will protect the outdoor street vendors from heat exposure and provide cooling strategies, such as growing trees and other forms of shade and the provision of accessible water sources close to outdoor workers’ operation areas.
This study was confined to assessing heat stress among outdoor street vendors due to time and resource constraints. For it to be holistic it should have covered all outdoor workers, including those operating backyard industries, however the results are still valid and can apply to every outdoor-setting activity.
As heat-related effects are new phenomena in developing countries, more research is needed on climate change impacts on public health in different community groups and on developing heat-prevention guidelines appropriate to developing countries. Further studies can evaluate the monitoring systems used in the country to reduce heat-related risks and measure the current government heat-prevention policies. Other studies can compare street vendors with other outdoor workers.
The study was supported by the Australian research funds through Edith Cowan University.
Citation: Ngwenya B, Oosthuizen J, Cross M, Frimpong K (2018) Heat Stress and Adaptation Strategies of Outdoors Workers in the City of Bulawayo, Zimbabwe. J Community Med Public Health Care 5: 034.
Copyright: © 2018 Bigboy Ngwenya, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.