Risk Assessment: A Methodology Renovation (unpublished paper) by Xander Lacson

DAVID XANDER LACSON Risk Assessment: A Methodology Renovation BENVGSH02 (30 credits) Module 2 â&#x20AC;&#x201C; Formal Essay 3525 words / 250-word reflection / 3 January 2017

Abstract This study proposes to ‘renovate’ the risk assessment methodology applied by UCL’s Institute for Sustainable Heritage student cohort of 2016-2017 during the Environmental Study of St. Paul’s Catacombs (SPC) Complex – Rabat, Malta, last November 2016. Through a comparative analysis and synthesis of different approaches i.e. Brokerhof’s and Bülow’s (2016) QuiskScan, Waller’s (1994) Cultural Property Risk Assessment Method, Michalski’s (1992, cited in Riksantikvarieämbetet, 2015b) ABC method, the UNESCO Amman Office (2012) Case Study for Petra and various related literature, this study proposes an enhanced risk assessment methodology for the SPC. The discussion will focus on evaluation of risks to the heritage assembly only, and shall exclude risk mitigation strategies. In addition, the study shall not delve on any or all risks assessments for visitors, staff etc. Heritage: Value and Preservation The purpose of heritage managers is to preserve cultural property in an efficient and sustainable manner (Cassar, 2009). This is founded on identifying, preserving and enriching the values of heritage collections. As custodians of heritage, our aspiration is to pass on our heritage to future generations with the best usability and accessibility. In doing so, we are also the main consumers of heritage. We use heritage to understand our identity, culture and society, amongst other things. We also substantiate the preservation of heritage by ascribing values. These values are more than often in economic, social, cultural or environmental terms (Walter, 2013). Therefore, managing and preserving the values that we ascribe to heritage supports the act of preserving the materiality of heritage property. Heritage: Accessibility versus Preservation Accessibility to heritage allows for its consumption. By this, we mean every activity that we do towards heritage – studying, analysing and even merely appreciating it. Without access, we cannot perform these activities. Though in allowing access to heritage, we expose it to chances for damage. This is the reason why the major issue for heritage professionals is balancing accessibility versus preservation. Preservation of heritage on one end of the spectrum, involves the idea of restricting access. There is a direct correlation between the degree of accessibility and risk. As we increase access, we are in turn increasing exposure of a heritage object to certain threats (Riksantikvarieämbetet, 2015b).

Heritage: Risk, Threats and Hazards Risk can be described as the presence of threats or hazards that create an opportunity to cause damage, which in turn may cause loss of value. Therefore, a threat only becomes a risk when the heritage property has a chance of contact with the threat. Following the risk scenario: source + path + object effect, we give the example of a tourist (source) visiting the catacombs (path) carving graffiti on the rock-face (effect). Risk is therefore the possibility of this event to cause damage (Ball and Watt, 2001, cited in UNESCO Amman Office et al., 2012). In the field of heritage, risk can further be defined as either natural such as earthquakes, or mad-made (anthropogenic) threats such as vandalism or even mismanagement (Camuffo, 1997; UNESCO Amman Office et al., 2012). To further contextualise the concept of risk, we can make a parallel between risk in terms of heritage to other industries such as business and finance. The risk of a business venture is the probability that an investor would not be able to recover his investment. Therefore, we can compare the loss of investment in a business to damage and a loss of value in the heritage sector. In the wider economic context, financial institutions regularly publish ‘riskrating’ scores that describe an economy’s risk magnitude reflecting its ability to grow or diminish an investor’s capital based on market performance (Kuhner, 2001). Risk Assessment & Risk Management in Heritage Heritage professionals have devised different strategies in evaluating heritage collections (British Standard, 2010). These strategies fall under the umbrella of documentation and data analysis, which are needed in determining the stability of a heritage object (National Park Service, 2016). Stability can be defined as an object’s state of undergoing physical changes or deterioration (Ashely-Smith, 2001). The strategies used in the research at SPC were (1) values assessment, (2) pest collection and analysis, (3) condition surveys, (4) mapping of change and deterioration, (5) environmental monitoring, (6) risk assessment and (7) SWOT (strengths, weaknesses, opportunities and threats) analysis. Risk assessment in heritage management involves three main activities i.e. (1) identifying risks by recognising vulnerability versus the presence of threats, (2) analysing the relevant risks to the heritage collection, to know if the threats are in contact with the collection or not and (3) evaluating these risks based on an agreed methodology (Riksantikvarieämbetet, 2015a/b). On the other hand, risk management is the overarching strategy that encompasses the risk assessment, establishing (1) a foreground and context which

precedes the risk assessment, and (2) strategies for risk mitigation as a resolution to the risk assessment itself. The process of risk management is an intuitive practice as it allows for consultation and review at every stage in order to continually improve the method. Therefore, the risk assessment is a vital tool for decision-making for the protection of the stability, materiality and values of heritage property (Taylor, 2005). Its main purpose is to identify and mitigate probable eventualities (risk) of a loss of value (damage). Without the risk assessment, we are unable to identify and prevent these future eventualities that endanger heritage. Since risk assessments expound on eventualities, it is a forward-looking strategy. On the other hand, other strategies such as condition surveys can be described as more retrospective, as they are an assessment of an object’s ‘condition’ based on its historical environment and circumstances. St. Paul’s Catacombs (SPC) Complex – Rabat, Malta According to Abela, Cardona and Zahra (2015), St. Paul’s Catacombs Complex (SPC) in Hal Bajjada (Rabat) contains one of Malta’s biggest underground burial sites of its kind (see Figure 1). Dating back to the Roman times, wall inscriptions denote use of the catacombs by pagan Roman, Christian and Jewish cultures at that time. The complex was opened to the public in October 2015 after site rehabilitation and development financed by the European Regional Development Fund (ERDF) as part of Figure 1: Site photo featuring the gate and entrance structure leading the biggest SPC catacomb.

the wider Archaeological Heritage Conservation Project of Heritage Malta. This entailed the construction of temporary structures to house the Visitor Centre and

other auxiliary spaces, landscaping, pathways connecting site elements, improved access and lighting in each catacomb. SPC’s most outstanding quality is its archaeological and historical value as it provides a great resource for artefacts and data regarding the multicultural communities that have co-existed in Malta ever since. Thus, the site also exhibits a unique social value. The environmental study by the UCL ISH cohort last November 2016, assessed the impacts of the site development one year after it was opened to visitors.

Risk Assessment (RA) in the context of SPC There were six risk assessments produced by the UCL ISH students, i.e. Underneath the Visitor Centre (see Figure 4), a catacomb quarried to expose for top viewing via the glass floor of the Visitor Centre; Catacombs 12 & 17 (see Figure 5), which contains SPC’s only preserved fresco; the garage collection (see Figure 6) in temporary storage; the bone collection (see Figure 7) and metal collection (see Figure 8) in glass display cases in the Visitor Centre. The sixth RA for visitors will not be presented. As seen in the legend (see Figures 2 - 3), Risk Score = Frequency + Severity, Priority = Risk Score + Change of Value. The RA for Catacombs 12 and 17 though did not integrate change of value.

Figures 2 & 3: LEGEND. Quantitative values were assigned to frequency, severity and change of value, though the parameters were more descriptive. i.e. frequency scale of constant, sporadic, rare and extremely rare etc.

Figure 4: Underneath the Visitor Centre Risk Assessment (RA) highlighted the hazard types of flood, fluctuation in relative humidity and dissociation as those of ‘high’ priority.

Figure 5: Catacombs RA identified man-made damage, temp., humidity and maintenance (neglect) as ‘high’ priority.

Figure 6: Garage Collection RA identified dissociation amongst all type of hazards. RISK RATING HAZARD TYPE Traffic Vibrations Earthquakes Visitor Damage Erosion (Wind) Erosion (Water) Thieves Vandals Flood Water Plumbing Leaks Relative Fluctuation Humidity Extremes Fluctuation Temperature Extremes Dumping Pollution Chemical / Air Fire Light Exposure Custodial Maintenance Neglect Dissociation Pests

Visitor Centre - Bone

Physical Forces

FREQUENCY SEVERITY 3 1 0 0 0 0 0 0 1 1 2 3 2 0 0 1 2 1 1 0

1 3 0 0 0 3 2 1 0 1 2 3 3 0 1 3 1 2 1 2

RISK SCORE

CHANGE OF VALUE

PRIORITY

4 4 0 0 0 3 2 1 1 2 4 6 5 0 1 4 3 3 2 2

1 3 2 0 0 2 2 1 1 3 2 2 2 1 1 2 2 1 2 0

5 7 2 0 0 5 4 2 2 5 6 8 7 1 2 6 5 4 4 2

RISK RATING HAZARD TYPE Traffic Vibrations Earthquakes Visitor Damage Erosion (Wind) Erosion (Water) Thieves Vandals Flood Water Roof Leak Relative Fluctuation Humidity Extremes Fluctuation Temperature Extremes Dumping Pollution Chemical / Air Fire Light Exposure Custodial Maintenance Neglect Dissociation Pests

Visitor Centre - Metal

Physical Forces

FREQUENCY SEVERITY 3 1 0 0 0 0 0 0 1 2 3 1 3 1 3 1 2 1 1 0

0 3 0 2 3 3 2 1 0 2 2 2 2 1 3 1 1 1 1 2

RISK SCORE

CHANGE OF VALUE

RISK RESULT

3 4 0 2 3 3 2 1 1 4 5 3 5 2 6 2 3 2 2 2

0 1 0 0 0 2 1 1 1 1 1 1 1 0 1 2 0 2 3 0

3 5 0 2 3 5 3 2 2 5 6 4 6 2 7 4 3 4 5 2

Figure 7: Bone Collection RA identified earthquakes, extremes in relative humidity, fluctuation and extremes in temperature and fire amongst all types of hazards for priority.

Figure 8: Metal Collection RA identified both extremes in relative humidity and temperature and chemical or air pollution for the ‘high’ priority ranking.

Granting there was some correlation between the priority results of the risk assessments to the overall findings of the research, the methodology was quite arbitrary and did not seem to justify the RA results. In order to substantiate results and decrease the level of subjectivity, the following methodology weaknesses are identified for improvement: (1) Timing. The risk assessments were conducted towards the end of the research study, which proved to be counter-intuitive. Since risk assessment is a tool that integrates values and potential hazards, conducting them in the initial stage of site analysis will guide the efforts of the proponents to a more focused fact-finding method. Needless to say, conducting the risk evaluation as early as possible will facilitate in detecting any ‘red flags’ when performing lateral strategies such as mapping and environmental monitoring. (2) Lack of Values and Vulnerability Assessment. The initial stage of the methodology did not emphasize the values and inherent vulnerabilities of the heritage collection. Due to this, risk assessment was conducted for certain collections and hazard types that may not have needed much in-depth analysis, i.e. (1) the collection stored in the garage were mostly pottery fragments being less vulnerable and (2) pests were discovered to be a benign occurrence onsite. (3) Lack of ‘Fraction Susceptible’ Factor. The factor of severity in the risk equation did not clearly reflect if it integrated the ‘fraction susceptible’ factor. There should be consideration that certain risk types such as earthquakes or air pollution have the possibility of affecting the entire site or collection versus other risk types such as light exposure or flood that may only affect a portion of the collection. Even though we are to assess groups of items that are homogenous in nature, the exposure to certain risks may be controlled by its location onsite, making the fraction susceptible factor important for evaluation. (4) Scale and Scale Definitions. The scale used for frequency, severity and change in value were 0 – 3. It should have been noted that if a risk was scored as zero (0) in any of the factors, then that particular risk type should already have been removed from the assessment. In addition, the definitions for the score values such as ‘constant,’ ‘sporadic,’ ‘rare’ and ‘extremely rare’ for frequency were not highly

definitive. To avoid subjectivity, the parameters have to be quantifiable to a certain extent. The same holds true for severity and change in value. (5) Formula. The summation formula used was based on Michalski’s A+B+C Method which was also utilised for the Petra Case Study (UNESCO Amman Office et al., 2012). Michalski’s formula has three (3) factors scored in a range of 1 -5, producing the highest risk magnitude (RM) of 15. The aim of this proposal is to be able to suggest a formula that would produce a maximum RM of 10 for the reason that a scale of 1 - 10 should be easier to assimilate even without a legend. The Renovation to the Risk Assessment Methodology (1) Using the QUISKSCAN. This study proposes using Brokerhof’s and Bülow’s (2016) QuiskScan (Quick Risk Scan) to assimilate values and vulnerability in the initial stage. Vulnerability is defined as an object or site’s susceptibility to certain threats based on its inherent characteristics (Riksantikvarieämbetet, 2015b). This approach enables the user to review the macro-situation of a heritage collection prior to ‘zooming in.’ It identifies possible threats to the collection without having to go immediately in-depth in assessing if the threats pose a tangible risk to the heritage. To contextualise vulnerability, UNESCO’s Amman Office (2012) Case Study for Petra, emphasises that the fragile local sandstone of the monument determines its inherent vulnerability to natural erosion by wind and water. The same holds true for the SPC which is mainly composed of Maltese Globigerina Limestone (Cardona, 2016). The composition, fragility and porosity of this limestone make it inherently vulnerable to damage caused by salt and alveolar weathering amongst others (Rothert et al, 2007). In performing the QuiskScan, it is important to subdivide the heritage collection into homogenous groups to be able to assess inherent vulnerabilities for each. This study uses Michalski’s (1999 cited in Riksantikvarieämbetet, 2015b) and Waller’s (1994) 10 agents of deterioration (Canada, Heritage, and Institute, 2016). The grouping or anatomy for the QuiskScan are illustrated below (see Figure 9).

Figure 9: QuiskScan Application for SPC. Values Assessment and Vulnerability are coded as low (L), medium (M), and high (H). The results are colour coded as follows: RED (HxH), ORANGE (HxM, MxH), YELLOW (MxM), GREEN (HxL, LxH, MxL, LxM) and BLUE (LxL).

Regarding values assessment, Catacombs 12 and 17 were given a high (H) rating except for the catacomb underneath the Visitor Centre (UVC), which was given an ‘M’ for the reason that this was the one particularly ‘sacrificed’ for the quarrying intervention. The collections displayed in glass cases in the Visitor Centre were given ‘H,’ the stone specimens displayed without glass cases - ‘M,’ and artefacts in the garage storage - ‘L,’ for the reason that they may have been of least priority in being transported to the Natural History Museum of Malta for analysis (Cardona, 2016). (2) Identifying Collections for Assessment. The results of the QuiskScan clearly indicate that the bone and metal collections on display at the Visitor Centre and Catacomb 17’s fresco (which was not included in the previous RA) have the highest results, exhibited by the red cells with ‘HH,’ followed by Catacombs 12 and 17 and the catacomb UVC, having the most orange (HM and MH) and yellow cells (MM). The QuiskScan illustrates the reason why there is no immediate necessity to perform an in-depth risk assessment for (1) all collections stored in the garage and (2) the pottery and stone collections on display, due to the lack of red (HH) and orange (HM and MH) results, and (3) the wood and glass collection, due to their minimal quantities within the collection anatomy and a rating of ‘M.’ (3) Identifying Risks for Assessment. After identifying the collection anatomy, we proceed to identifying the relevant risks. The QuiskScan indicates which agents of deterioration should be investigated for the risk assessment, based on the red ‘HH’, orange ‘HM’ or ‘MH’ and yellow ‘MM’ rating. It also shows that the entire collection anatomy is not inherently vulnerable to pests. Therefore, pests can be excluded in any of the risk assessments, as well as the onsite monitoring and data-collection.

(4) Integrating Fraction Susceptible and Redefining the Scale. From the previous method, the components retained for this proposal are (P) probability (formerly frequency) and (LV) loss of value (formerly change of value). The component of (FS) fraction susceptible replaced severity, alluding to Waller’s (1994) suggestion that severity can be expressed by LV and FS. The suggested scale is the range of whole integers 1 to 5, to avoid producing a range that is too wide to comprehend (see Figure 10). The legend describes each value with corresponding quantitative parameters to aid in the risk assessment. This range eliminates zero (0) which could yield an RM product of zero (0) if the RM formula uses multiplication. Figure 10: New RA LEGEND, probability (P), loss of value (LV) and fraction susceptible (FS). Scale of 1-5 for P, LV & FS with corresponding definitions.

(5) Choosing the Formula. There are three formulae proposed for this study, Risk Magnitude (RM) A, B, and C. Formula A, derived from the ABC method used in the Petra Case Study (UNESCO Amman Office et al., 2012), implies that each component has a cumulative effect on RM. Formula B, mathematically implies that FS affects the ‘preliminary’ score deduced as P + LV. Formula C, derived from B makes FS a fraction of ‘5’, being the maximum in the FS scale. The proposal does not include Waller’s (1994; 2016) RM=P x LV x FS formula because the RM value does increase if the integer ‘1’ is assigned to P and LV. SUGGESTED FORMULAE FOR RISK MAGNITUDE: RM A = P + LV + FS RM B = (P + LV) x FS RM C = (P + LV) x FS 5

Although Formula A and B are straightforward, the concept of fraction of a whole is not encapsulated by either adding or multiplying the FS value as a whole integer. Using Formula C suggests that if FS is given a ‘5,’ then the formula makes FS/5 equal to ‘1,’ implying the entire collection whereas, a value less than ‘5’ would make FS/5 a fraction of ‘1.’ This formula also yields an RM scale of 1 – 10, which allows for RM values to stand alone even without the legend. Therefore, the proposed formula would be RM C (see Figure 11), which coincidentally produces the tightest range of RM values. The results of the new risk assessments are shown (see Figures 12 - 16).

Figure 11: RM C SCORING LEGEND & MATHEMATICAL ILLUSTRATION for RM based on all 3 formulae - using a "straight-streak" scoring i.e. 5 - 5 -5, 4 - 4 - 4, etc.

NEW SPC RISK ASSESSMENTS (Hazards encircled in RED were top priority in previous RA)

¸ ¸ Figure 12: Catacomb Under the Visitor Centre RA: Highest RM computed for salt weathering, followed by earthquakes, salt efflorescence, dissociation, and RH fluctuation.

Figure 13: Catacomb 12 & 17 RA: Highest RM computed for earthquakes, rain infiltration and dissociation, followed by visitor damage and light exposure causing microbiological growth.

Figure 14: Fresco at Catacomb 17 RA: Highest RM computed for visitor damage, followed by light causing microbiological growth, and thieves or vandals.

¸ Figure 15: Bone Collection in the Visitor Centre RA: Highest RM computed for earthquakes, RH fluctuation, thieves/vandals, dissociation, followed by maintenance neglect, RH extremes, and fire.

Figure 16: Metal Collection in the Visitor Centre RA: Highest RM computed for earthquakes, RH fluctuation, thieves/vandals, dissociation followed by light exposure, RH extremes, maintenance neglect.

Discussion The apparent shift in results from the previous methodology to this proposed risk assessment is based on several factors. Applying the QuiskScan allowed analysis of the collection anatomy and risk typologies that needed more attention. The addition of the fresco RA and removal of the garage RA can be justified. Also, the reorganization of risk types would not have materialised. For example, the prominence of salt weathering, salt efflorescence and (sun) light exposure causing microbiological growth as specific risks to the Catacomb UVC could be attributed as the result of its quarrying and exposure to the elements. Vis-à-vis the prominence of visitor damage, (LED) light exposure, and rain infiltration as specific risks to the fresco, Catacombs 12 and 17 could be attributed as a result of the site development in general. This correlates to the reports by the Universitat de Barcelona et al. (2012) and Tobit Curteis Associates LLP (2011) on the presence of microbiological growth and the recommendations on site drainage to avoid excessive rain water seepage into the catacombs, respectively. The addition of fraction susceptible affected RM values. In the previous method, Catacomb UVC’s flood RM was computed to be the highest whereas the new method’s flood RM was reduced due to FS. The expansion of scale values to a ‘1 to 5’ range, coupled with quantifiable parameters allowed for precision in determining the appropriate scores with less subjectivity, especially for P and FS. Lastly, the repeated prominence of extreme or fluctuating relative humidity risk correlates to the findings of the UCL ISH cohort’s (2016) environmental data monitoring, indicating that the Visitor Centre’s structure is unable to buffer the external environment, thus were found to be outside prescriptive ranges (Canadian Conservation Institute and Michalski, 1992; Delgado Rodrigues, 2015). Also, the repeated prominence of maintenance neglect and dissociation merely illustrates the fact

that all of these risk exposures and their consequent management ultimately fall under the responsibility of Heritage Malta, which is controlled by human factor (Greeves, 2001). Conclusion and Recommendations The purpose of risk assessment is to allow heritage professionals not be risk-averse but rather, to be better equipped in risk management. In accomplishing a risk assessment that is based on the preservation of values, heritage professionals are better able to balance accessibility with preservation for future stakeholders. In this proposed risk assessment methodology, the use of the QuiskScan provides an overview of the situation. This allowed for the assessment of the collection against more relevant threats by isolating significant risks and making a more granulated methodology. The suggested adjustments to the factors, scale and formula had greatly reduced the level of subjectivity. Therefore, results are assumed to be more conclusive and substantiated. In the scenario that a more precise risk assessment is warranted, it is recommended for future researchers on the topic to devise a reliable manner for quantifying loss of value (Cultural Heritage Agency, 2014). Reflection on the Group Work The research study trip in Malta was a great experience for myself and if I could speak for the other students, I am sure they would say the same. The modules learned during the 2week trip instantly gave the course a more technical and scientific perspective. I would definitely say that the team worked well together as we complemented each otherâ&#x20AC;&#x2122;s various skill sets and technical know-how. Everyone fell into certain roles and almost all possible tasks were fulfilled. Even with a few minor language communication challenges, I could say with great satisfaction that this never hindered getting ideas across and processing responsibilities. Everyone was encouraging to one another, and it was interesting to note that the addition of the part-time students definitely added great value to the experience, owing to their personalities and skills. Despite the steep learning curve and rapid knowledge absorption, the scheduling of tasks was very well organized. I was really contented and pleased at the amount of technical knowledge that was learned during the Malta experience. Though I would suggest that perhaps it would help if the risk assessments were done in the beginning. Most of the time, I was rather lost with the data and was always in doubt on what to look out for. I feel that performing the risk assessment early would have helped us in knowing what to look out for during the other assessments and knowing how to present and assimilate the data and information.

Bibliography Abela, K., Cardona, D. and Zahra, D. (2015) Archaelogical Heritage Conservation Project ERDF032. Edited by Margaret Abdilla Cunningham and Godwin Vella. Malta: Heritage Malta. Ashley-Smith, J. (2001) ‘Pratical Uses of Risk Analysis’, The Paper Conservator, 25(1), pp. 59–63. British Standard (2010) EN 31010:2010: Risk Management: Risk Assessment Techniques. U.K. Brokerhof, A.W. and Bülow, A.E. (2016) ‘The QuiskScan — a quick risk scan to identify value and hazards in a collection’, Journal of the Institute of Conservation, 39(1), pp. 18–28. Camuffo, D. (1997) Saving our architectural heritage: The conservation of historic stone structures: Report of the Dahlem workshop on saving ..., Berlin, march 3-8, 1996. Edited by Norbert S. Baer and Rolf Snethlage. New York: John Wiley & Sons. Canada, G. of, Heritage, C. and Institute, C.C. (2016) Agents of deterioration - Canada.Ca. Available at: http://canada.pch.gc.ca/eng/1444330943476 (Accessed: 2 January 2017). Canadian Conservation Institute and Michalski, S. (1992) Temperature and Relative Humidity: The Definition of Correct/Incorrect Values. Cardona, D. (2016) November. Cassar, J. (2016) November. Cassar, M. (2009) ‘Sustainable Heritage: Challenges and Strategies for the Twenty-First Century’, Association for Preservation Technology International Bulletin, 40(1), pp. 3–11. Cultural Heritage Agency - Ministry of Education, Culture and Science, Netherlands (2014) Assessing Museum Collections: Collection Valuation in Six Steps. Delgado Rodrigues, J. (2015) ‘Defining, mapping and assessing deterioration patterns in stone conservation projects’, Journal of Cultural Heritage, 16(3), pp. 267–275. doi: 10.1016/j.culher.2014.06.007. Greeves, M. (2001) ‘Risk management at the Fitzwilliam museum, Cambridge’, Journal of Architectural Conservation, 7(3), pp. 67–79. doi: 10.1080/13556207.2001.10785303.

Kuhner, C. (2001) ‘Financial Rating Agencies: Are they Credible? Insights into the Reporting Incentives of Rating Agencies in Times of Enhanced Systemic Risk’, Schmalenbach Business Review, 53(1), pp. 2–26. National Park Service - Museum Management Program (2016) The Museum Handbook Part I: Museum Collections. Washington DC, U.S.A.: National Park Service. Riksantikvarieämbetet (2015a) Modelling and communicating loss of value in risk assessment - José Luiz Pedersoli Jr. Available at: https://www.youtube.com/watch?v=l59TLJTi_PQ (Accessed: 2 January 2017). Riksantikvarieämbetet (2015b) Risk assessment for cultural heritage - Agnes Brokerhof. Available at: https://www.youtube.com/watch?v=2zbk_nFzFl0 (Accessed: 2 January 2017). Rothert, E., Eggers, T., Cassar, J., Ruedrich, J., Fitzner, B. and Siegesmund, S. (2007) ‘Stone properties and weathering induced by salt crystallization of Maltese Globigerina limestone’, Geological Society, London, Special Publications, 271(1), pp. 189–198. doi: 10.1144/gsl.sp.2007.271.01.19. Taylor, J. (2005) ‘An integrated approach to risk assessments and condition surveys’, Journal of the American Institute for Conservation, 44(2), pp. 127–141. doi: 10.1179/019713605806082365.

Tobit Curteis Associates LLP (2011) Survey and Monitoring of the Environmental Conditions 20102011: St. Paul’s Catacombs, Rabat, Malta. Cambridge, U.K. UCL Institute for Sustainable Heritage and Student Cohort 2016-2017 (2016) Environmental Study of St. Paul’s Catacombs Complex - Rabat, Malta. . UNESCO Amman Office, Anna, P., Azadeh, V., Giorgia, C., Katholieke Universiteit Leuven, Mario Santana, Q. and Koen, V.B. (2012) Risk Management at Heritage Sites: A Case Study of the Petra World Heritage Site. Amman, Jordan: UNESCO. Universitat de Barcelona, Dr. Gómez Bolea, A., Dra. Álvaro Martín, I., Dra. Hernández Mariné, M. and Dr. Llop Vallverdú, E. (2012) Study of Biological Communities at St. Paul’s Catacombs: Revise Final Report. Barcelona, Spain: University de Barcelona. Waller, R. (1994) ‘Conservation Risk Assessment: A Strategy for Managing Resources for Preventive Conservation’, Studies in Conservation, 39(2), pp. 12–16. Waller, R. (2016) Risks to tribal cultural heritage assessment. Available at: https://www.youtube.com/watch?v=0fbqHOv-5Fw (Accessed: 2 January 2017). Walter, N. (2013) ‘From Values to Narrative: A New Foundation for the Conservation of Historic Buildings’, International Journal of Heritage Studies, 20(6), pp. 634–650.