Tools for assessment of corrosion and soiling in the multipollutant situation Johan Tidblad and Vladimir Kucera Corrosion and Metals Research Institute, Stockholm, Sweden

Corrosion trends in Europe in the multipollutant situation

Fifth Framework Programme, MULTI-ASSESS (2002-2005) Fifth Framework Programme, Energy, Environment and Sustainable Development Key Action: City of Tomorrow and Cultural Heritage Contract number: EVK4-CT-2001-00044

Partners and subcontractors Swedish Corrosion Institute, Stockholm (co-ordinator) Academy of Fine Arts, Inst. of Sciences and Technologies In Art, Vienna, Austria Bavarian State Department of Historical Monuments, Munich, Germany Swiss Federal Labs. for Materials Testing and Research (EMPA), Dubendorf Swedish Environmental Research Institute Ltd. (IVL), Gothenburg CNR Institute for Atmospheric Pollution, Rome, Italy University of Athens, Department of Applied Physics, Greece Middlesex University, School of Health and Social Sciences, London, UK SVUOM, Prague, Prague/Czech Republic Building Research Establishment (BRE), Watford, UK Norwegian Institute for Air Research (NILU), Kjeller Institute of Precision Mechanics, Warzaw, Poland Riga Technical University, Centre for Conservation of Stone Materials, Latvia LISA - Université Paris XII, France Estonian Environment Research Centre (EERC), Tallinn University of Antwerpen, Department of Chemistry, Belgium

Expected main results

Passive samplers for the ”missing” pollutants : nitric acid and particles

HNO3 concentration 44 0.0 0.5 1.0 1.5 2.0 2.5 5 HNO3 21 24 35 23 26 34 27 46 7 41 10 49 8 40 3 50 1 45 16 15 14 36 31 33 13 43

Relation of particle deposition and PM10 concentration

Dose-response functions, ICP Materials (period 1987-95)

Dose-response functions multi-pollutant/MULTI-ASSESS programme incl Dose-response functions multi-pollutant/MULTI-ASSESS programme incl. HNO3 and PM10 (1997-2001)

SO2 dependence

Tolerable corrosion and pollution The tolerable level is the maximum level at which a tolerable corrosion/soiling occurs. It should be based on experiences from restoration / maintenance work for cultural heritage objects.

Soiling, limestone DRF: ΔR/R0 = [1-exp(- klimestone x PM10 x t)] ΔR/R0, relative loss of reflectance k, soiling constant PM10, in µg m-3 t, time in years Critical soiling level ΔR/R0 = 35%

Tolerable pollution levels in the multi-pollutant situation Definition of a tolerable corrosion rate, Kt, depending on use and material, implicitly defines a tolerable multi-pollution situation, which can be reached by reducing one or several of the multi-pollutants: Kt= fdry(T, RH, [SO2]t, [HNO3]t, ...) + fwet(Rain[H+]t)

Summary of DRF, tolerable effects and target levels

Air Quality Directive 99/30/EC Limit values of pollutants, µg m-3

Use of DRF for mapping: Steel, Czech Republic (2001) The tolerable corrosion rate is 20 µm

Kit for assessment of deterioration and pollution Carousel with limestone specimens Soiling sampler Passive samplers pollutants Steel and zinc specimens

Tools developed for assessment of corrosion and soiling FOR NATIONAL AND INTERNATIONAL POLICY Dose-response functions for multipollutant situation: - Tolerable deterioration, tolerable pollution levels - Mapping of areas with exceedance - Calculation of cost of damage FOR LOCAL MANAGEMENT STRATEGIES DRF – tolerable pollution levels, tolerable deterioration Kit for rapid assessment of corrosion and soiling Passive samplers for nitric acid and particles

Conclusions and gaps of knowledge The new corrosion functions for the multi-pollutant situation involve, besides the effect of SO2, also the effect of particulate matter and HNO3. Assessment of target levels for materials show that they are at least as sensitive to pollution as human beings and therefore cultural heritage should be considered in future assessment of limit values for pollutants. The effect of traffic, in particular in the vicinity of main roads, is only in part covered by the new equations. Therefore, future efforts should focus on the corrosion and soiling effects of particular matter, nitric acid and other pollutants, for example those associated with the use of alternative fuels, in the traffic situation.

<Additional figures>

Dose-response function for zinc from ICP Materials (N=98, R2=0.84) ML = Dry deposition + Wet deposition = 1.4[SO2]0.2·e0.02Rh + f(T)·t0.85 + 0.03Rain[H+]·t ML = Corrosion attack (mass loss) T = Temperature RH = Relative humidity [SO2] = SO2 concentration (air) Rain = Amount of precipitation [H+] = [H+] concentration (precipitation) t = exposure time

Tolerable corrosion rates For practical purposes, tolerable corrosion rates (Kt) can also be defined as a multiple (n) of the background corrosion rate (Kb), where n is based on experiences from restoration / maintenance work for cultural heritage objects: Kt = n · Kb

Tolerable corrosion rate based on background corrosion rates and n=2.5

Example of use: tolerable SO2 levels