We are living in a moment in which the dual crises of public health and the environment are merging, the confluence of the two magnifying the destructive power of each. As they run together, the crosscurrents of disease and ecological deterioration build on one another, becoming increasingly turbulent and damaging forces that are tearing at the very fabric of our societies. Climate change, chemical contamination, and unsustainable resource use are all exacerbating ill-health the world over. The health sector itself is paradoxically contributing to these very environmental health problems, even as it attempts to address their impacts. Through the products and technologies it deploys, the resources it consumes, the waste it generates and the buildings it constructs and operates, the health sector is a significant source of pollution around the world, and therefore an unintentional contributor to trends that undermine public health [1] .

Health care services consume large amounts of water and energy, use significant volume of hazardous and non-hazardous materials and are responsible for emissions [2] . In United State, hospitals are the second part of energy high consumptions and they consume energy twice that of conventional buildings [3] . Brazilian hospitals use more that 10% of the country’s total commercial energy by consume vast amounts of energy [4] . The National Health System in UK has reported that it releases 25 million tones Carbone per year; on the other hand, 25% of total gas production in the public sector [5] . In United State, hospital incinerations are one of the four main producers of Dioxin and Mercury [6] .

Since hospitals provide health care to the communities, they are known through intrinsic link with social responsibility and sustainability aspects related to the environment and people [7] . Sustainability is the human requirement in the 21st century. For human societies, identifying sustainability requires systematic thinking, consisted decision making and accepting that human systems are located within the natural systems [8] . Therefore, hospitals should have a trend to protect the environment and try to implement the concept of sustainability. The concept of sustainability is essentially a response to the subjects related to the green hospital and includes various aspects of natural sciences, development of alternative energy and favorable energy storage systems [9] . Green Hospital is the hospital that constantly improves public health by reducing environmental impacts and eliminating the role of hospitals in cause burden of diseases. Green hospital recognizes the relationship between human health and environment and this shows that it is understandable through its governance, strategies and operations. Green Hospital connects local requirements with environmental measures and methods of primary prevention through active engaging in efforts to improve health of community and environment, health equity and green economy [1] . While there is no recognized and specific model of green hospital in the entire world, many of hospitals and health systems around the world simultaneously have taken steps to reduce their environmental impacts, help to public health and save money [1] [10] - [12] .

There are determined goals due to successful implementation of green hospital program, including: leadership which is essential at all levels to foster green and healthy hospitals. This can be achieved through education, goal setting, accountability, and incorporating these priorities in all external relations and communications [1] . The health sector also consumes significant amount of chemicals. Through assessment the exposure of health institutes of with chemicals, health sector can protect patients and its staff and does actively safe management of chemicals [13] . Wastes also generated during caring activities have potential risk of infection and injury more than other type of waste [14] . However, it seems that some of the wastes produced in medical units have not been considered seriously, especially in developing countries [15] . Health sector uses significant amount of energy resulted from fossil fuels [16] . Hospitals can significantly reduce emission of greenhouse gases and costs of energy over the time through the use of alternative forms of clean and renewable energy [17] . Health care centers use large amounts of water. Climate changes with its associated effects such as drought, melting glaciers and depletion of aquifers have intensified water shortage [18] . It is recommended that all of these areas that need to water be evaluated and help to reduce water consumption [19] . Buildings in their current design are such boxes that convert sources to wastes. For this reason, they have immeasurable impacts on natural environment and life system. It should be considered in a sustainable framework. The only solution is Green building that means design and construction functions that reduce negative impacts on the environment. Hospitals and health systems purchase various types of products including chemicals, electronic and plastic materials to produce energy, drug and food [20] . Purchasing results in health sector have significant impact on environment [21] . Creation and implementation green purchasing policies such as purchase environmentally friendly products can play central role in achievement to green and healthy hospital purposes [17] .

As mention above, green hospital has some goals which can contribute the hospital organization to move safety for their patients, staff and communities. Despite the establishment of Green Hospital in some countries of world, global efforts just address the climate change and protect the environment and the literature has been less paid to the green hospital. Although a lot of researchers have been separately worked on each of the green hospital dimensions including green building; unfortunately, the little research has been conducted about green hospital dimensions comprehensively [22] . In Iran also, some researchers have performed projects on this subjects such as hospital waste management, energy management in hospitals and assess accreditation standards of green hospital model have been done [23] - [28] . But, lack of a comprehensive study that includes all aspects of this approach and on the other hand, the necessity of protect environment by hospitals that are savior of health themselves, motivate us to evaluate dimensions of green hospital in all of teaching and private hospitals covered by Tehran University of Medical Sciences (TUMS).

This is a descriptive-analytical study that evaluated green hospital dimensions in teaching and private hospitals under supervision of Tehran University of Medical Sciences in year 2014.

From a total of 19 hospitals in sample, 9 hospitals (47.4%) were teaching and 10 hospitals (52.6%) were private. Workspace in 4 hospitals (21.1%) was over than over than 30 thousand square meters, in 6 hospitals (31.6%) was between 10 thousand to 30 thousand square meters and in 9 hospitals (47.4%) it was under than 10 thousand square meters. 6 hospitals (31.6%) had less than 100 active beds, seven hospitals (36.8%) had more than 250 active beds and 6 hospitals (31.6%) had between 100 and 250 active beds. 8 hospitals (42.1%) were less than 45 years old, 6 hospitals (36.1%) were between 45 to 70 years old and 5 hospitals (26.3%) were over than 70 years old. Table 2 shows the frequency of obtained scores in each dimension.

As it is shown in Table 2, hospitals obtained only 59.5% of total attainable score. Leadership obtained highest score and building obtained lowest.

According to the results, while average score in private hospitals was more than teaching hospitals in all dimensions except leadership and chemicals, there was no significant relationship between any of Green hospital dimensions and type of hospital statistically (P-value > 0.05) (Table 3).

Furthermore, based on our findings showed in Table 4, there was statistically significant relationship between chemicals and number of staff, energy and number of active beds, water and number of active beds, building and hospital age, purchasing and workspace (P-value < 0.05). Any statistically significant relationship between other Green hospital dimensions and hospital variables (age, workspace, number of active beds and number of staff) was not found.

According to the results of this study, under study hospitals earned only 59.07% of total attainable score and they lost significant percentage in all of dimensions. In Shamir about effectiveness of environmental management study, Tehran’s hospitals were not in good condition [29] . Leadership earned the highest score thought among all of Green hospital dimensions. Farzianpour’s study y supports this result [24] . It seems that efforts and commitment of hospital managers to environmental aspects and establish the green and healthy hospital have had impact. Totally, it is advised to hospital managers to be aware of environmental lows and guidelines and commit to theme. Furthermore, it is recommended that administrators adopt global environmental systems such as ISO 14001 and Eco-Management and Audit Scheme (EMAS) to improve hospital activities in order that they can be able to monitor and evaluate their ongoing activities while they are lunching the system.

Dimensions of building, water and waste had lowest scores respectively while in Farzianpour’s study dimensions of purchasing and chemicals had lowest scores [24] . About building, more than half of the hospitals in the study were older than 45 years. It is important to emphasize that the strategies of Green building are not applicable for new constructions. In many cases, existing buildings can be equipped to achieve many systemic im- provements that are reaching in new buildings [19] . Based on scientific evidences, buildings should improve or- ganizational performance and cause sustainability in the environment. So, the only practical solution to reduce

negative impacts of buildings on environment is Green building. In another words, buildings which consume lower energy and release lower Carbon in the atmosphere [20] . In this regards, changing in performance of existing buildings to use of daylight, natural ventilation, using of canopy and light reflectors, solar panels, solar water heaters and Green roof are recommended. Moreover, there are recognized standards to access hospital building and the best known of them are Green Star, BREEAM¹ and LEED² [30] . These tools share a common concept: principles of Green building including used land, water and energy consumption, sourcing, environment and interior quality [31] [32] . Several studies have shown that hospitals which have became successful to get certificate, earn more benefits [20] [22] [33] . So, it is recommended to Iran’s hospitals, especially private hospitals to try to get international reliable certificates. We advise to give energy label for buildings including hospitals (Such as domestic appliances), use integrated design process by contractors including Iran Housing Company and develop national standards for green hospital.

Findings of this study recognized water conservation management as priority for improvement. Studies of Farrokhshahi and Jabbarvand have estimated that water consumption in Iran’s hospitals are 1.35 and 1.63 times the standard value respectively [20] [34] . Health facilities can protect water resources by accurate measurement of water consumption, installing efficient water equipment and technologies, development of drought-resistant perspective, and quickly repair the leaks [19] . Totally, hospitals obtained about 56% of total score in waste and it was a bit better in private hospitals. That was consistent with the findings of Farzianpour et al. [26] . Their study indicated that private hospitals were in better condition than teaching hospitals about the way of separation, collection, temporary storage and transportation of waste to temporary storage place in hospital and then to final disposal place. Hospital waste management including avoidance, reuse, recycling and disposal can be useful to reach one of the basic principles of green hospital, hospital waste management. Hospital administrators can manage waste through compost, recycle, better purchasing (downsizing package, use reusable products instead of disposables and buy recycled products) and minimize waste transport. By these actions, it will be possible to fulfill the hospital mission “no harm to patients, itself, society and environment” in addition to cost-saving [22] . It seems necessary to develop a comprehensive action plan in order to fulfill the fundamental standards and promote the weakness of Green hospital standards. There was no statistically significant difference among teaching and private hospitals. However, private hospitals attained higher score in all dimensions except of leadership and chemicals. It seems that private hospitals have more fund and their managers have more freedom to create a better picture of the quality of hospital services.

Hospitals should be revised in both structural and constructional aspects. Green Hospital will be achieved through strong commitment of health staff to take the leadership role in the prevention of health and environmental protection in the future. According to improvable points of green hospital standards, through developing operational plan, it will be possible to fulfill the hospital mission “no harm to patients, itself, society and environment” in addition to cost-saving. Moreover, trying to carry out evaluation and take certifications from international credible organizations such as LEED, GREEN STAR and BREEAM can help to improve the environmental management of the hospital. Considering the existing limitation, conducting a national comprehensive study yields the validation of obtained analytical results and allows us to generalize them.

The study is based on a M.Sc. thesis which supported by TUMS. We sincerely grateful all staff, managers and employees of selected hospitals covered by TUMS that helped us to conduct the study.