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Asgari A, Hadian Dehkordi M, Noohi N. (2026). Assessment of Environmental Parameters (Temperature, Humidity, Light, and Pollutants) in the Manuscript Library of the Golestan Palace World Heritage Site with a Preventive Conservation Approach. Athar. 47(2), 165-186. doi:Athar.1961.4030.1
URL: http://athar.richt.ir/article-2-1961-en.html

The Library and Documentation Center of the Golestan Palace World Heritage Site, as one of the richest repositories of Iranian manuscripts, houses invaluable works from the Qajar and Pahlavi periods. The organic materials of these manuscripts, such as paper, leather, and ink, are highly sensitive to environmental conditions, with temperature, humidity, light, and pollutants playing a critical role in their preservation. In this study, as the first comprehensive assessment of the environmental conditions of the Golestan Palace Manuscript Library, the storage conditions were evaluated using a preventive conservation approach. Field data on temperature, relative humidity, light intensity, ultraviolet radiation, dust, and biological contamination were collected and compared with international standards. The results revealed that, with lighting sources on and curtains raised, light intensity (up to 700 lux) and ultraviolet radiation (up to 176 µW/m²) exceeded permissible limits. The average temperature (26.3°C) and relative humidity (16.3%) with high fluctuations were outside standard ranges. Additionally, high dust concentrations and various bacterial and fungal microorganisms were detected in the storage air. The main reasons for dust and biological pollutants in this storeroom include its proximity to the palace’s green spaces and its urban location with high traffic and movement. This study emphasizes the need for implementing preventive conservation strategies, such as establishing a regular environmental monitoring program, improving infrastructure facilities, sealing window gaps, modifying site cleaning methods (preventing dust dispersion), and controlling lighting conditions (both natural and artificial). The findings not only enhance the preservation of the valuable Golestan Palace collection but also serve as a model for other manuscript libraries and archives in Iran.
Keywords: Manuscripts, Preventive Conservation, Environmental Conditions, Golestan Palace, Environmental Monitoring.

Introduction
The Golestan Palace Manuscript Library, part of the UNESCO World Heritage Site in Tehran, Iran, serves as a vital repository of Persian cultural heritage. It houses an invaluable collection of manuscripts, historical documents, scientific texts, and artistic works, predominantly from the Qajar and Pahlavi eras. Among its treasures are over 200 nationally registered items, including exquisite Qurans, fingernail-script manuscripts, and the six-volume illustrated “One Thousand and One Nights” commissioned by Naser al-Din Shah Qajar between 1269 and 1276 AH (1852–1859 CE). This masterpiece stands out for its vibrant calligraphy, illumination, and joyful colors, representing the pinnacle of late Qajar artistry. Additionally, three globally registered works, Baysonghori Shahnameh (Inventory No. 716), Khamsa of Nezami (No. 1913), and Jami’al-Tawarikh of Rashid al-Din (No. 2254), underscore the library’s international significance. These artifacts not only reflect Iran’s rich history, culture, and artistic legacy but also serve as essential resources for scholarly research worldwide.
Manuscripts, due to the organic nature of their materials, are highly vulnerable to environmental factors such as temperature, relative humidity, light intensity, UV radiation, dust, and biological pollutants (such as fungi and bacteria). Previous studies have demonstrated that unsuitable environmental conditions can accelerate chemical and physical degradation processes; for instance, excessive light can cause color fading and paper brittleness, while high humidity facilitates fungal growth. In manuscript storage facilities, the lack of adequate ventilation systems, insufficient light control, and the presence of biological contaminants can lead to irreparable damage. These challenges are particularly pronounced in the historic and landscaped context of the Golestan Palace complex, located in the bustling heart of Tehran, complicating the preservation of manuscripts even further.
In this regard, a preventive conservation approach, which focuses on preventing potential damage through the management of environmental conditions and the identification or reduction of risk factors, can be an effective strategy for safeguarding this invaluable heritage. This requires the measurement and monitoring of environmental parameters and awareness of their status.
Despite the importance of environmental research for the preservation of museum collections and historical documents, including the manuscript repository of the Golestan Palace, such investigations are rarely conducted in the country. This study, adopting a preventive conservation approach, aims to assess and monitor environmental factors including temperature, relative humidity, light intensity, UV radiation, and biological pollutants in the Golestan Palace library repository using scientific tools and methods. The goal of this research is to answer the question: “How do the environmental conditions of the Golestan Palace manuscript repository compare to the defined standards for institutions such as museums and archives, and what strategies can be proposed to improve the preservation conditions and mitigate the threats to these valuable works?”

Discussion 
In this study, a comprehensive assessment of environmental parameters was conducted in the manuscript library of the Golestan Palace. The evaluation focused on key factors including temperature, relative humidity, light intensity, UV radiation, dust levels, and biological pollutants. Field measurements were taken using precise instruments such as data loggers for temperature and humidity, lux meters for light intensity, and UV sensors for measuring ultraviolet exposure. Dust was sampled passively with 23 microscopic slides placed at various heights and locations in the storage and experts’ room for 90 days, analyzed under a polarizing microscope to identify particle composition, with density estimated using Terry and Chilingar’s visual comparison chart. Furthermore, biological contamination was assessed via the Omeliansky sedimentation method. The data were then compared with international standards established by organizations such as the National Information Standards Organization (NISO), the Canadian Conservation Institute (CCI), and the Image Permanence Institute (IPI).
The study’s findings reveal significant environmental challenges in the Golestan Palace manuscript library. Light intensity measurements showed peaks of 700 lux and UV radiation up to 176 µW/m² when curtains were raised, far exceeding the recommended 50 lux for sensitive materials like manuscripts. These conditions risk photochemical degradation, causing fading and brittleness in paper and inks. Temperature averaged 26.3°C, and relative humidity was critically low at 16.3% (9.7–26.8%), deviating from CCI standards (18–20°C, 45–55% RH). Low humidity increases paper brittleness and static electricity, attracting dust, while temperature fluctuations cause material expansion and contraction. The calculated isoperm index (63.5) indicates acceptable but suboptimal preservation conditions.
High dust levels, comprising plant pollen, urban soot, and paper fragments, were found, particularly near windows and high-traffic areas. This is attributed to the library’s proximity to green spaces and urban traffic, with open window gaps and inadequate ventilation filters exacerbating contamination. Microbial analysis identified fungi (Aspergillus, Penicillium) and bacteria (Staphylococcus, Bacillus) in the air, with higher concentrations (up to 885 CFU/m³) in high-traffic zones like the experts’ room. These microorganisms, thriving in dust and fluctuating humidity, pose risks of biodeterioration.

Conclusion 
The assessment of environmental parameters in the manuscript library of the UNESCO World Heritage Site, Golestan Palace, reveals critical insights into the preservation conditions of its invaluable collections. As a repository of rare manuscripts from the Qajar and Pahlavi periods, the library’s environmental management is vital for safeguarding these irreplaceable artifacts. The study demonstrated that several environmental parameters, specifically light intensity, ultraviolet radiation, temperature, and relative humidity, exceeded the recommended international standards, placing the manuscripts at considerable risk of degradation.
To address these challenges, a multi-tiered preventive conservation framework is proposed. Short-term interventions include installing UV filters, keeping curtains lowered, and minimizing artificial lighting during non-essential hours. Medium-term solutions involve deploying HEPA- filtered HVAC systems and humidifiers to stabilize environmental conditions. Long-term strategies encompass infrastructure upgrades like window sealing and enhanced cleaning protocols to reduce dust and microbial infiltration. Staff training in environmental monitoring and conservation practices is crucial for sustainable implementation.
This research not only highlights the urgent need for improved environmental management practices at the Golestan Palace library but also serves as a model for other manuscript libraries in Iran and beyond. By addressing the identified challenges and prioritizing the implementation of these preventive measures, we can enhance the longevity and integrity of these cultural treasures for future generations to appreciate. The collaborative efforts of conservators, museum professionals, and relevant authorities will be essential in redefining approaches to the preservation of these delicate artifacts, ensuring they remain safeguarded against the ravages of time and environmental factors.