Occupational exposure to uncomfortable temperatures in two university presses of Costa Rica

Many industrial processes are carried out under conditions of high temperatures, creating discomfort among workers, and less frequently, a health risk, especially when heat is combined with poor ventilation and a lack of medical supervision. This problem has seldom been studied in Latin America, so this study measured the occupational exposure to overheating in workstations from the printing shops of two university publishers in a tropical city (San José, Costa Rica). We measured heat conditions in 55 workstations using a thermo-anemometer and a heat stress meter, both calibrated and certified. Workers use the workstations during the day but have several interruptions and we concluded that, even though there is a high percentage of dissatisfaction among workers regarding the temperature (50% to 80%), there is no risk of heat stress. To reduce the reported level of discomfort, we recommend that new workers be allowed an acclimation period and modification of rooms to allow more natural ventilation. Similar studies are needed in other Latin American countries, if our data are to be compared in a meaningful way.

Working conditions are determined in part by physical factors that can cause discomfort among workers.In many industries, heat is among the main complaints, and health care personnel needs to know whether it is just a matter of discomfort or a full health risk (Barrios-Casas & Paravic-Klijn 2006).High heat levels are a particularly serious public health threat for the elderly and persons with pre-existing health conditions (Richard et al. 2011).The problem also a ects children even in countries where large amounts are spent in their well being, for example, in school buildings (Jenkins et al. 2009).
Exposure to excessive heat also has a negative impact on productivity, even in acclimatized individuals, and the symptoms include increased heart rate and excessive sweating or lack of it, sometimes leading to medical emergencies such as heat exhaustion, heat stroke and heat stress.Other health conditions that can develop from heat include rashes, cramps, dehydration, discomfort, apathy, memory loss and worsening of chronic diseases  (Parra 2003, Suárez 2006, Bertoldi et al. 2007, Toscani 2007, Caballero & Suarez 2009, Ro-Ting & Chang-Chuan 2009).
The high temperature and humidity levels that are frequent in tropical cities, added to the vigorous physical activity of traditional printer shops and the use of protective equipment, make exposure to high temperatures more frequent, and therefore more di cult to control, in large parts of Latin America (Almirall et al. 2006).These conditions are expected to worsen because of the current global warming.In recent years, the study of working conditions has led to a decrease in hazardous or unsafe exposures in places like Colombia, for example (Instituto Nacional de Seguros de Costa Rica 1997, Coneo-Mendoza & Donado-Arias 2009).However, little has been published on this subject in Latin America (Rocha et al. 2010), and to our knowledge, nothing is known about the working conditions in the print shops of any university, so our study contributes to a poorly known subject that will become more important because of global warming.Even in temperate countries, climate change increases potential threats to comfort and health.For example, in Britain, during a hot period, more than 40% of bedrooms failed the recommended overheating criteria (Mavrogianni et al. 2010).A study that used dynamic computer simulation with de ned domestic building variants found that even with a window-opening schedule, the average internal temperature in Europe could be over 28°C for almost 12% of the year and that with climate change there will be cooling problems in bedroom areas for approximately a third of the year (Peacock et al. 2010).
The study was done as part of an overall analysis of working conditions.We are certain that this is the rst study on the levels of exposure to high temperatures of the sta of university publishers in Costa Rica.

Subjects
We evaluated the workstations in two university presses in San José, Costa Rica (total: 55 workstations).The facilities do not exceed 400m 2 each and only have small windows that cannot be opened.

Methods
We chose the printing buildings because they have heavy industrial machinery that emits heat and because their buildings have little air circulation.Furthermore, our experience is that this type of work requires a higher metabolic rate than o ce work.
We made heat measurements in the hottest time of the year (March 5 through April 15, 2010), during the hottest part of the day (11-14 hr), because we were looking for a possible problem of over-heating.The city never reaches signi cantly low temperatures so we did not study the periods with low temperatures.
Institution 1 has 20 workstations and Institution 2 has 27 workstation in one building (o set printers) and 8 workstations in another building (digital printing machine).
We set 20 measuring points in Institution 1 and 35 points in Institution 2 and made 20 measurements per day at each point.We used an Extech HD300 Thermo-Anemometer and an Extech HT30 Heat Stress Meter; both instruments were calibrated and certi ed.We measured dry and wet temperatures, balloon temperature, relative humidity, and wind speed.
We labeled measurements according to the following standards that are o cial for Costa Rica (see References for details about their methods and symbology):   (Table 1), so there mean temperatures are close to the limit but do not exceed it.
The temperature dissatisfaction levels (Table 2) indicate that 70% of the workers are dissatis ed with the heat in Institution 1 and 80% are dissatis ed in Institution 2.
At a metabolic value under 200kcal/hour, there is no risk of heat stress, but workers are exposed to more than the optimal temperature for development of any activity which is 22°C (Organización Internacional del Trabajo 2005).However, a slight increase in metabolic load, at the temperatures we measured in these workstations, would lead to heat stress (Instituto Nacional de Seguros de Costa Rica 1997, 2001, Parra 2003, Suárez 2006, Toscani 2007).Sustained overheating can lead to heat syncope, cramps, heat exhaustion, heat stroke and dehydration (Instituto Nacional de Seguros de Costa Rica 1997Standard 31-08-09-1997, Bertoldi et al. 2007, Ro-Ting & Chang-Chuan 2009).
The Fanger values are extremely high, reaching 80%: they should not exceed 5% (Instituto Nacional de Seguridad e Higiene en el Trabajo 2000).Our results could be evaluated with the ISO 7730 norms (International Standards Organization 2005 ) as well as with the Fanger Method, but we used the second.The Fanger Method was proposed in 1973 to evaluate thermal comfort, and it takes into account clothing, metabolic rate, radiant temperature and relative humidity.Even though the method is not new, we used it instead of the ISO 7730 because it is the method used in Costa Rica, where we made the study (Instituto Nacional de Seguros de Costa Rica 1997).
From our results with this method, it is clear that even though not exposed to dangerous overheating, the sta that uses these workstations su er from heat discomfort.The laborers work half hour shifts with the workstations and do complementary work away from the workstations every other half hour.Work consists mainly of placing books on particular machines, cutting and binding paper, and checking for faulty copies.It is a repetitive work that includes lifting light weights.The work is lighter in the colder and quiet digital pressroom, while the other rooms use older, o set machinery and are more noisy and hot, making the whole operation uncomfortable and stressing after some time.The elderly and people with pre-existing health conditions need specially careful protection from excessive heat (Richard et al. 2011).In the two institutions that we studied, the sta is composed mainly of middleaged men.Women and elderly workers are few, but in 15-20 years most of the sta using these workstations will be elderly workers and thus they will be more susceptible to problems associated with overheating.If the equipment is updated before that, the potential problem will be reduced, but considering the nancial situation of these and other Latin American public universities, the update is unlikely to take place.

RECOMMENDATIONS
We recommend remodeling the three buildings to increase natural ventilation to reduce the levels of discomfort reported by the users of these workstations.Adding external shading can also reduce overheating signi cantly, especially if combined with a window-opening schedule (Jenkins et al. 2009, Peacock et al. 2010).
Furthermore, we suggest that new workers be allowed an acclimation period before starting the part of the work that consists of weight lifting and repetitive movements.
Similar studies are needed in other Latin American countries, if our data are to be compared in a meaningful way.

TABLE 2
Calculation of Fanger temperature dissatisfaction levels in two university presses of San José city, Costa Rica (2010)