Daniel Grosjean and Associates
California Institute of Technology

Daniel Grosjean
Jill Shankel
Glen R. Cass
Period of Activity: 7/90 to 4/91

Project Abstract
On a number of occasions, the Getty Conservation Institute's (GCI) efforts to conserve architectural sites and museum collections have led to requests that environmental assessments be conducted. Exposure assessments are often requested because little data exist on an international or global scale that can be used to estimate the likely hazard when cultural properties are exposed to environmental stresses.

With the recent development of new sensitive and cost-effective passive monitoring methods, it appears possible to establish a worldwide monitoring network to economically assess the exposure of cultural properties on a global scale. This global monitoring network would be based on passive monitors and on the assumption that cultural site managers and museum officials around the world would be willing to cooperate to the extent of placing a simple passive-monitoring package at their site and return it to California.

If this can be done, it would be a major accomplishment-the first global monitoring program to simultaneously acquire data on levels of damaging air pollutants, soiling rates, and light fading hazards using identical methods at all sites. Accurate comparisons of exposure risk at different cultural heritage sites could be made. Warnings could be issued to managers of sites where severe conditions are observed. Research at GCI on matters of protection of materials from damage due to air pollution could be targeted to the locations where those results are most needed. Follow-up studies could be aimed at areas where the greatest risk of accumulated damage is present.

Since the concept of a global passive-monitoring network is entirely novel, the first step must be to undertake a feasibility study to explore whether or not such a program could in fact be implemented. This feasibility study was the object of this project, which addressed the issues of network design, passive monitoring technology, selection of parameters to be combined into a passive sensor unit, "pilot-scale" field trials, logistical aspects, time schedule, and cost estimates.

Primary Publications
Grosjean, D., J. Shankel, and G. R. Cass, "Feasibility of a Global Network to Monitor the Exposure of Cultural Properties to Environmental Stresses," Final Report to the (Conservation at the Getty) Institute, April 1991.

ABSTRACT-The major conclusion of the analysis is that a global monitoring network based on passive monitors is indeed feasible, and this at a very small fraction of the cost of operating the same network with conventional instrumental methods. Our findings, conclusions, and recommendations are as follows:

a. The variables to be measured should include ozone, sulfur dioxide, formaldehyde, and deposited particles. Some information will also be obtained on light intensity and temperature.

b. Passive monitoring methods are available for the parameters selected but are currently at different phases of development and validation. Inexpensive direct-reading methods are given priority over those involving chemical analysis. Validated direct-reading methods are available for ozone, deposited particles, and light exposure. The ozone passive monitor is described in some detail to illustrate performance specifications for use in a global network. Chemical analysis methods are available for formaldehyde and sulfur dioxide. Ongoing work with formaldehyde may lead to the development of a direct-reading method. Research leading to a direct-reading method for sulfur dioxide should be initiated.

c. A compact, rugged, inexpensive sensor unit can be assembled that includes passive monitors for these parameters and can be shipped, deployed, returned, and documented.

d. With respect to network design, a spatial interpolation algorithm was used to assess the feasibility of estimating the spatial distribution of an environmental parameter on a global basis from a limited number of discrete monitoring sites. Using worldwide population density as a test database, we found excellent agreement between actual values and those calculated from a discrete network of 500 sites, which constitute only a 0.4% sample of a global 1 degree x 1 degree grid.

e. A pilot-scale field trial is recommended. The pilot scale study should include 10% of the number of sites adopted for the global network, should be several months' duration, and should be targeted at a small number of countries, e.g., a single country or 2-3 countries with a high density of cultural property and poor air quality, i.e., with a high potential for environmental stress to cultural property. The pilot-scale study should include all parameters and protocols, including quality assurance, envisioned for the global network.

f. The time schedule for completion of a global monitoring effort is estimated to be 36 months, of which the first 6 are devoted to methodology optimization, the next 12 to a pilot study and to planning of the global network, the following 12 months to full-scale operation of a one-year network of passive monitors, and the last 6 months to data analysis, interpretation, and reporting.