The effect of exposure to cold on dexterity and temperature of the skin and hands

Abstract

Objectives. This study aimed to determine the impact of low temperature (−1 °C, +5 °C) on manual dexterity and hand skin temperature after 1 h of exposure when using two types of protective gloves. Methods. Ten male participants wore double gloves or single gloves, when spending 1 h in a climatic chamber at −1, +5 or +20 °C. Before and after the cold exposure, measurements of mean weighted body skin temperature, hand skin temperature, the Purdue Pegboard Test and hand grip strength were performed. Results. There were statistically significant differences in the values of mean weighted body skin temperature and left and right hand skin temperature between the study variants. Conclusion. No effect of cold exposure (−1 °C, +5 °C) on manual dexterity was observed, but there was an effect of −1 °C temperature change on weighted mean skin temperature and hand skin temperature during 1 h of exposure. The decrease in both right and left hand skin temperature after cold exposure was the largest for −1 °C while using single gloves, and differed significantly from the other variants.

KEYWORDS:

• manual dexterity
• cold exposure
• skin temperature
• hand temperature
• cold environment

1. Introduction

Dexterity is defined as a motor skill determined by a range of arm, hand and finger movements, as well as the ability of the hands and fingers to manipulate [1–5]. This definition includes both fine finger dexterity (e.g., writing, picking up a coin) and manual dexterity (e.g., digging, placing a saucepan on the hob) [5]. To assess dexterity, objective and representing reality task tests are used [3–5]. The objective tests include, among others, the Purdue pegboard test, power grip strength and pinch grip strength [5].

Manual dexterity can be affected by environmental conditions, e.g., low temperature [3,4,6,7]. In a cold environment, constriction of the peripheral blood vessels and cooling of the distal parts are observed [3,4,8–10]. This may cause a decrease in the temperature of the skin of the hands/fingers, which can translate into, e.g., reduced physical performance, longer reaction time, reduction in muscle contraction force and impaired manual dexterity [3,4,6,8,10]. The reduction in dexterity is greater the more the work performed depends on finger dexterity [11]. It was reported that when the skin temperature decreased from 24 to 7 °C, a loss of performance was observed for filling boxes with cubes (11%), passing needle and thread through a cube (22%), fastening screws by hand (26%), tying knots in rope (28%), fastening screws with a screwdriver (36%) and putting rings around pins (38%) [10,11]. In addition, the lower the skin temperature of the fingers/hands, the greater the decrease in dexterity [11]. If the temperature of the fingers drops to 14–15 °C, the dexterity may be reduced [1,6,10–13]. According to European Standard EN ISO 9886:2004 [14], the local skin temperature should not be lower than 15 °C (in particular for the extremities: face, fingers and toes).

As many factors affect manual dexterity, it is difficult to establish precise guidelines on the relationship between hand skin temperature and predicted loss of sensory and motor functions [6]. It is suggested that significant deterioration of hand function occurs when the hand/finger skin temperature drops below 14–15 °C [1,3,4,10–13].

Therefore, it is important not to allow the hand skin temperature to drop below a certain limit [10]. As the temperature of the hands (and hence blood flow) decreases, manual dexterity will gradually deteriorate. Therefore, maintaining warm fingers, hands and forearms is important for proper functioning of the hand [15]. However, some researchers have tested the opposite situation. They found that finger dexterity decreased even if the hands were kept warm (>28 °C) but the body was cooled down [16–19]. Kiess and Lockhart [16] reported that mean weighted body skin temperature decreasing below 24 °C alone impairs manual dexterity. On the other hand, finger dexterity may be maintained during 3 h of exposure to –25 °C even with low finger blood flow, if the finger skin temperature is maintained at a relatively high level (28–35 °C), the change in body heat content is >−472 ± 18 kJ, the mean weighted body skin temperature is >28.5 ± 0.3 °C and the forearm muscle temperature is >29.8 ± 0.5 °C [19].

Reducing the skin temperature of hands/fingers, and thus also manual dexterity, may impair work efficiency and increase the incidence of accidents [3,4,10,20]. Maintaining proper manual dexterity is important, not only at work but also in everyday life. Many tasks require high manual dexterity, as well as fine finger dexterity (e.g., sorting small items in cold storage). However, this efficiency may be decreased by a cold working environment.

Understanding the impact of the environment on the skin temperature of the hands and their dexterity will allow for better protection of workers in the workplace. Often, despite properly selected hand protection, workers complain about the lack of comfort during their work [21]. In addition, in Poland, work in a cold microclimate (in rooms with an air temperature below 0 °C) defines a job as work in special conditions that allows workers to apply for ‘bridging pensions’ in accordance with the Polish Act of 19 December 2008 on bridging pensions (Journal of Laws 2022.1340).

The aim of this study was to determine the impact of low temperature (−1 °C, +5 °C) on manual dexterity and hand skin temperature after 1 h of exposure when using two types of protective gloves.

2. Materials and methods

A study of the effect of air temperature when using two types of protective gloves on manual dexterity and hand skin temperature was carried out in a climatic chamber with the participation of a selected group of volunteers.

2.1. Participants

Ten right-handed, male subjects, not exposed to a cold environment for several weeks, participated in the study (Table 1).

Table 1. Characteristics of volunteers.

Parameter	Mean ± standard deviation
Sex	Male
Age (years)	21.8 ± 3.2
Body mass (kg)	76.7 ± 10.3
Height (m)	1.8 ± 0.1
BMI (kg/m^2)	22.8 ± 2.2
VO2max (ml/min/kg)	30.5 ± 2.8

Note: BMI = body mass index; V_O2max = maximal oxygen consumption.

Healthy volunteers (after a medical interview) were selected for the study on the basis of an aerobic fitness qualification test. Details of the qualification test have been described previously [3]. It should be emphasized that some of the volunteers were the same as in the previous study [3]; however, the studies differed in terms of aims and analysed indices.

Volunteers were informed about the conditions of the study and asked to prepare properly before the study. Participants were required to abstain from caffeine and alcohol, be well rested and not perform exercise for 24 h before the preliminary and experimental trials.

The study procedures were approved by the Committee of Ethics and all participants provided written informed consent.

2.2. Test conditions

Each participant underwent five study variants: four as cold exposure and one as a control condition (Table 2).

Table 2. Test variants.

Test variant	Air temperature (°C)	Tested gloves
V.1	+5	Type A
V.2	+5	Type B
V.3	−1	Type A
V.4	−1	Type B
V.5 (control conditions)	+20	Bare hands

Volunteers visited the laboratory five times, with at least 1 day off between tests. The order in which the study variants were conducted was randomized.

Participants spent 1 h in the climatic chamber (Weiss, Germany) for each study variant. During this time, they performed different manual tasks, such as sorting of small elements by shape or colour and completing Valpar Component Work Samples 1 (VCWS 1 Small Tools [Mechanical]; Bases of Virginia, USA) [22], as described in detail previously [3]. Before and after being in the climatic chamber (cold exposure and control conditions) the participants performed the Purdue pegboard test and hand grip strength test to determine their manual dexterity. The test scheme is shown in Figure 1.

Figure 1. Test scheme: pre-test (preparation for test); 1 h of exposure in climatic chamber; and after the test.

The tests outside the chamber were performed without protective gloves at room temperature (19–20 °C).

2.3. Gloves and clothing

The participants were dressed in the following set of clothing: thermal underwear, a cotton T-shirt, a fleece jacket, woollen socks, a woollen cap, an insulated jacket and insulated trousers (dungarees) in cold exposure. In the reference conditions (variant V.5), standard work clothes, a cotton T-shirt and thin socks were worn by the volunteers. Shoes were adapted to the prevailing conditions [3].

In cold conditions (in the climatic chamber) two types of gloves were used during the tests: glove type A, double glove (white knitwear + black fleece) (variants V.1 and V.3); and glove type B, single glove (polyester) (variants V.2 and V.4). The tested protective gloves differed in the type of material and the type of fibres used [3]. The convective cold test and the contact cold test for the gloves were performed on a thermal hand model according to Standard EN 511:2006 [23]. The tested gloves achieved the first performance level of resistance to convective cold, as well as the second (type A gloves) and third (type B gloves) performance levels of resistance to convective cold [3].

The thermal insulation of the clothing ensemble was tested in the climatic chamber on the thermal manikin (NEWTON, USA) according to Standard EN 342:2017 [24] and Standard EN ISO 15831:2004 [25]. The total thermal insulation of protective clothing was 0.415 m² °C/W (2.68 clo), so this set of clothing may be used at an air temperature of both +5 and −1 °C [3].

2.4. Tested parameters and research equipment

2.4.1. Skin and hand temperatures

Skin and hand temperatures were recorded throughout all conditions at 30-s intervals using a data logger i-button (Maxim Integrated, San Jose, USA). Metal chip skin thermistor sensors (i-button: DS1923-F5, Maxim Integrated, San Jose, USA) were positioned at five measurement points on the skin: left hand, right hand, right calf in front (right shin), neck and right scapula.

The mean weighted body skin temperature (T) was calculated by weighting four from the five points (left hand, right shin, neck, right scapula) by representative areas according to Standard EN ISO 9886:2004 [14]: $\begin{array}{rl}T& =0.28T_{\mathrm{neck}}+0.28T_{\mathrm{right}\mathrm{scapula}}+0.16T_{\mathrm{left}\mathrm{hand}}\\ & +0.28T_{\mathrm{right}\mathrm{shin}}.\end{array}$

2.4.2. Manual dexterity

2.4.2.1. Purdue pegboard test – hand and finger movements

The Purdue pegboard consists of two parallel rows with 25 holes each and metal pegs. The task is to take, one by one, the metal peg from the cup and place it in the row of holes. The test result is the number of pegs placed in the holes within 30 s. The test was performed for both hands separately [26].

2.4.2.2. Hand grip strength

Hand grip strength was measured in a standing and upright position. The participants squeezed the dynamometer with the left or right hand with maximum force. The force exerted on the dynamometer was recorded during the measurement. Each measurement was repeated twice, and the higher (maximum) force value was selected for the analysis of test results.

2.5. Statistical analysis

Statistical analysis was performed to evaluate the differences (after exposure compared to before exposure) in the weighted mean skin temperature, hand skin temperature, grip strength and manual dexterity (Purdue pegboard test) using the Friedman analysis of variance test (STATISTICA version 9.0). In the case of statistically significant changes, the Wilcoxon signed-rank test was used. The level of statistical significance was set at p < 0.05.

3. Results

3.1. Mean weighted body skin temperature

Values of mean weighted body skin temperature as well as hand skin temperature, before and during the test, were calculated as the mean value from 1 min near time-points (e.g., ‘before’ was calculated as the mean value from 1 min before entering the climatic chamber; ‘after’ was calculated as the mean value from 1 min before exiting the climatic chamber [from 59 and 60 min in the climatic chamber]).

Mean weighted skin temperature values (with standard deviation) for 10 participants before and after the test, depending on the study variant, are shown in Figure 2.

Figure 2. Mean weighted skin temperature values of volunteers before, at 20 and 40 min, and after (60 min) the test, depending on the variants. Note: bars = mean values, whiskers = standard deviation.

There were statistically significant differences in the values of the mean weighted body skin temperature (calculated as the value after minus the value before exposure in the climatic chamber) between the study variants (Table 3). The greatest drop in temperature before and after exposure was noted for variant V.4. It differed significantly from any other variants of the study. For type A gloves, there was a significantly smaller decrease in the weighted mean skin temperature at an air temperature of +5 °C (variant V.1) than at −1 °C (variant V.3). For the V.5 variant (reference conditions, without a glove, in lighter clothing), a significantly smaller temperature drop was noted than for the V3 and V4 variants (Table 3).

Table 3. Difference in skin temperature (skin temperature after cold exposure minus skin temperature before cold exposure) for variants V.1–V.5.

	Hand skin temperature (°C)
Study variant	Left hand	Right hand	Mean weighted skin temperature (°C)
V.1	0.0 ± 1.5^‡	0.9 ± 1.3^†,‡	0.3 ± 0.5^†,‡
V.2	−1.3 ± 2.2^‡	−0.1 ± 1.7^‡	0.3 ± 0.7^‡
V.3	−1.9 ± 2.6^‡	−0.5 ± 1.9*^,‡	−0.4 ± 0.7*^,‡,§
V.4	−4.4 ± 1.3*^,**^,†,§	−3.5 ± 1.2*^,**^,†,§	−1.3 ± 1.1*^,**^,†,§
V.5	−0.3 ± 1.3^‡	−0.1 ± 0.9^‡	0.5 ± 0.7^†‡

* Significantly different from variant V.1.

** Significantly different from variant V.2.

^† Significantly different from variant V.3.

^‡ Significantly different from variant V.4.

^§ Significantly different from variant V.5.

3.2. Hand skin temperature

Mean values of skin temperature (with standard deviation) on the left and right hands before and after cold exposure for 10 participants (depending on the test variant) are shown in Figures 3 and 4.

Figure 3. Mean values of skin temperature on the left hand before and after cold exposure, depending on the test variant. Note: bars = mean values, whiskers = standard deviation.

Figure 4. Mean values of skin temperature on the right hand before and after cold exposure, depending on the study variant. Note: bars = mean values, whiskers = standard deviation.

Statistically significant differences (post-exposure and pre-exposure; calculated as the value after minus the value before exposure in the climatic chamber) in the mean left hand skin temperature were observed between the study variants (p < 0.05; Table 3). Variant V.4 differed significantly from the other variants. For the V.4 variant, the largest decrease in skin temperature on the left hand was noted after cold exposure, compared to the other variants (p < 0.05).

Statistical analysis of differences (post-exposure and pre-exposure) in mean skin temperature values for the right hand also showed significant differences between the study variants (p < 0.05; Table 3).

For the V.1 variant, a significantly smaller decrease in the mean skin temperature on the right hand was observed than for the V.3 variant and the V.4 variant (for the V.1 variant, an increase in temperature was observed). The decrease in right hand skin temperature after cold exposure was the largest for the V.4 variant and differed significantly from the other variants (Table 3).

3.3. Manual dexterity tests

3.3.1. Purdue pegboard test

Mean (with standard deviation) values obtained in the Purdue pegboard test for the right and left hands depending on the study variant are shown in Figure 5. A similar number of pegs were placed before and after the examination. The performed statistical analysis did not show statistically significant differences in the difference (calculated as the value after minus the value before exposure) in the number of pegs placed between the test variants for both the left hand and the right hand.

Figure 5. Mean values obtained in the Purdue pegboard test for the right hand (RH) and left hand (LH), depending on the study variant. Note: bars = mean values, number of pegs, whiskers = standard deviation.

3.3.2. Grip strength

The mean (with standard deviation) values of the grip strength for the left and right hands for 10 participants depending on the study variant are shown in Figure 6. On average, lower strength was observed after the study; however, differences (after exposure compared to before) in the hand grip strength between the study variants did not differ significantly for either the right or the left hand.

Figure 6. Mean values of grip strength for right hand (RH) and left hand (LH) for 10 volunteers depending on the study variant. Note: bars = mean values, whiskers = standard deviation.

4. Discussion and conclusion

The present study showed the effect of both the type of protective gloves and the ambient temperature on the hand skin temperature and on the weighted mean skin temperature.

As a result of exposure to cold, the body temperature drops, especially in the extremities. The decrease in skin temperature and blood flow in these areas contributes to reduced heat loss from these parts of the body. This results in a further reduction in skin temperature [5,9,10,20,27]. In this study, the impact of air temperature on mean weighted skin temperature was observed. A downward trend was observed after 20 min at −1 °C with single gloves. A significant decrease in mean weighted skin temperature was observed due to 1 h of exposure to −1 °C. The decrease in mean weighted skin temperature after exposure to −1 °C was significantly greater than in thermoneutral conditions (+20 °C). However, there was no statistically significant difference between the +5 °C and the +20 °C test conditions. By contrast, research by Oksa et al. [28] observed a lower mean weighted skin temperature after 2 h of simulated sausage packing at 4 °C (compared to tests at 19 °C). Perhaps in the present study the exposure time (1 h) at 5 °C was too short and the clothing was ‘too warm’ to show this difference. The intensity of the tasks performed also affects the reduction of skin temperature. The largest decrease in mean skin temperature was noted also after exposure to −5 °C or lower [29]. Similarly, Imamura et al. [7] observed a decrease in mean skin temperature to 27.1 ± 0.9 °C after 40 min of exposure to −10 °C in participants wearing NBC (nuclear, biological, chemical) clothing with a combination of ordinary rubber and cotton gloves. In contrast to cold exposure, at 20 °C the mean skin temperature changed to a small extent (0.2–1.0 °C) [7]. In the present study, the values obtained after exposure to −1 °C were also statistically significantly lower than the values after exposure to +5 °C (regardless of the tested gloves). It should be noted that the decrease in skin temperature has been observed in various studies, regardless of the method of skin temperature determination [28–30]. In this study, both the ambient temperature and the type of gloves used during exposure to cold had an impact on the mean weighted skin temperature after exposure in the climatic chamber. A greater decrease in mean weighted skin temperature was observed at −1 °C for type B gloves than for type A gloves. These results confirm that gloves affect the amount of heat loss (body/hand temperature). Depending on the type of gloves, heat loss can be reduced by up to 60–90% [31,32]. However, even the use of protective gloves does not fully protect the fingers/hands from cooling [3,4,7,33]. This is due to the cylindrical shape of the fingers, which promotes heat loss [7,34–36]. A significant influence of ambient temperature and type of gloves on the hand skin temperature was observed. The largest decrease in mean temperature on both the right and left hands was recorded after exposure to −1 °C using type B gloves (variant V.4). On the right hand, the influence of air temperature on hand skin temperature was observed for both gloves. Significantly lower values of hand skin temperature were recorded after exposure to −1 °C in relation to the air temperature of +5 °C. On the left hand, a statistically significant effect of air temperature was noted only for type B gloves. Saedpanah et al. [37] described lower palm temperature in outdoor car mechanic workers after exposure to cold air compared with neutral air. In contrast to our research, in the study by Saedpanah et al. [37] protective gloves were not used during exposure to low temperatures. Lower palm and hand skin temperatures were also observed after 40 min exposure to −10 °C compared to +20 °C in participants who wore NBC clothing with a combination of ordinary rubber and cotton gloves [7]. However, Imamura et al. [7] emphasized that hand temperatures remained at a high level during cold exposure at rest (20.1 ± 1.7 °C).

In the present study, exposure to cold did not affect the results of the manual dexterity tests (Purdue pegboard test, hand grip strength).

The Purdue pegboard test has been shown to be a reliable and valid measure of manual dexterity at room temperature [29,38,39]. However, it was demonstrated that manual dexterity at ambient (room) temperature does not correlate with dexterity at low temperature [39]. In this study there was no observed impact of cold exposure on manual dexterity (assessed by the Purdue pegboard test). Regardless of the environmental conditions (5 or −1 °C), there was no difference (comparing after to before) in the number of pegs insert into the holes. In contrast to this study, the manual dexterity measured with the Purdue pegboard test was lower after 130 min of exposure to −20 °C (thin gloves) [30]. Elton et al. [5] also observed the negative impact of a cold environment (20 min, 5 °C) on the Purdue pegboard test results – there was a 7% reduction of dexterity after cold exposure. Wiggen et al. [29] also noted the significant effect of temperature on Purdue pegboard test performance at −5 and −15 °C compared to 22 °C. It was suggested that the mean weighted body skin temperature must decrease below 24 °C to impair manual dexterity [16,19]. Moreover, Clark [40] reported that finger dexterity performance might decrease when hand skin temperature fell to 13 °C, but was unaffected at a hand temperature of 16 °C (it is not described which part of the hand was examined) [19,40]. In the present study, the minimum hand skin temperature and the weighted mean skin temperature for individual participants were higher than the previously reported values. This was true even in the case of variant V.4, where the lowest recorded values were observed (minimum participant skin temperature on left hand 21.2 °C and on right hand 22.9 °C and weighted mean skin temperature 27.9 °C for variant V.4). This may be one reason why we did not observe an effect of exposure to cold on manual dexterity as measured by the Purdue pegboard test.

Ramadan [41] observed that low hand skin temperature (5 °C) had a significant influence on hand grip strength in comparison to hand skin temperatures of 25 and 45 °C. Exposure to a cold environment could have an influence on hand grip strength. Saedpanah et al. [37] reported that grip strength in car mechanics working at a temperature of 0 °C and below decreased by 10.3% compared to neutral air (24–31 °C) [37], which may be related to the reduction of the hand skin temperature. In the present study, no impact of low air temperature on the hand grip strength was observed. Flouris et al. [30] also did not observe any impact of 130 min of exposure to −20 °C on hand grip strength. Likewise, no effect of temperature (22, 5, −5, −15 and −25 °C) was noted on grip strength in participants wearing standard protective clothing in the petroleum industry [29]. Moreover, Elton et al. [5] did not observe a statistically significant difference in power grip strength, although there was a slight reduction (3%) in the cold environment (5 °C) compared to thermoneutral conditions (19–24 °C). The lack of effect of cold exposure on grip strength may be due to the lack of changes of muscle temperature [5,29]. The muscle force is dependent on muscle temperature, but isometric force production during the hand grip strength test only slightly depends on a muscle temperature of 25–35 °C [29]. It was found that hand grip strength decreased when the hand skin temperature was <25 °C and the forearm muscle temperature was <30 °C [7,42]. The participants in this study wore clothes that were properly selected for the environment, which may contribute to the probable lack of temperature reduction in the extrinsic hand muscles in the forearm, which is consistent with Elton et al. [5] and Wiggen et al. [29]. Although in the present study the forearm muscle temperature was not measured, the relatively high average skin temperature would suggest there was no drastic decrease in muscle temperature, which is in line with the reports by Wiggen et al. [29] and Elton et al. [5]. Tochihara et al. [43] also did not find differences in hand grip strength between workers in cold storage units (−20 and −23 °C) and workers in a general storehouse (12–15 °C). The authors suggested that the lack of impact of cold exposure on manual dexterity may be due to: carrying out measurements in warm, comfortable rooms (as in the present study); a finger skin temperature above 15 °C (above the threshold for conditions that could affect manual dexterity); and the almost constant trunk skin temperature of around 35 °C during the study.

It is worth noting that during tests in a climatic chamber (during exposure to cold), an increase in the duration of individual activities simulating normal manual work at low temperatures was observed in our previous study [3]. It seems that the previous decline in manual dexterity may have been due to the influence of the type of gloves used rather than the effect of low temperature, which is consistent with another study [7].

The differences in the obtained results may be due to not analysing the mean values, but analysing the difference (after exposure compared to before exposure – the performance decrement) in the number of pegs placed and the difference in strength, contrary to other studies [3–5,29,30]. In addition, in this study the manual tests (Purdue pegboard test, grip strength) were performed with bare hands, unlike other studies where, e.g., thin gloves were used [30]. It should also be noted that the ambient temperature differed during manual dexterity tests. In this study, tests were performed after exiting the climatic chamber (after exposure to cold), while in other studies the tests were performed during exposure to cold [29,30]. Moreover, the way the tests were performed also differed from one study to another, e.g., during the hand grip strength test the hand was in line with the forearm [30] or the elbow was at a 90 °C angle [37], and during the Purdue pegboard test the dominant hand or both hands were used [5,30,39].

In conclusion, in the present study, no effect of exposure to a cold environment (−1 and 5 °C) on manual dexterity, as measured by the Purdue pegboard test or hand grip strength, was observed. The statistic analysis did not show any difference between the test variants. However, an effect of cold exposure on the weighted mean skin temperature and hand skin temperature of volunteers was observed. The decrease in both right and left hand skin temperatures after cold exposure was the largest at −1 °C while using single gloves, and differed significantly from the other variants. Notably, although there was only 1 h of exposure and proper protective gloves and clothes were used, the values of weighted mean skin temperature and hand skin temperature decreased.

Importantly, in real working conditions, the exposure time is several times longer. Although there were no significant differences between the variants (−1 and 5 C), future research should focus on smaller differences in air temperature to determine whether working at temperatures down to 1 °C affects the human body in the same way as working at <0 °C. Also, future research could make use of other VCWSs (for simulated sorting in, e.g., cold storage) and parameters for assessing manual dexterity. Additionally, the group of volunteers could be differentiated by gender.

Statements and declarations

All authors contributed to the study conception and design. Material preparation, data collection and analysis were performed by Orysiak Joanna, Młynarczyk Magdalena and Irzmańska Emilia. The first draft of the manuscript was written by Orysiak Joanna and all authors commented on previous versions of the manuscript. All authors read and approved the final manuscript.

Acknowledgements

This article is published and based on the results of a research task carried out within the scope of the fifth stage of the National Programme ‘Improvement of safety and working conditions’, supported within the scope of state services by the Ministry of Family and Social Policy. Task no. 2.SP.21 is entitled ‘Investigation of the influence of cold and cold microclimate on the physiological responses of the worker during exercise manual work’. The Central Institute for Labour Protection – National Research Institute (CIOP-PIB) is the Programme’s main coordinator.

Disclosure statement

No potential conflict of interest was reported by the authors.