Sources and Impact of Urban Air Pollution 25-27 October 2004 Venice Indoor Air Quality in Museums Franco De Santis CNR-IIA
Air quality and Cultural Heritage Pollutants contribute heavily to the deterioration of Cultural Heritage Gaseous pollutants such as ozone, sulphur dioxide and nitrogen dioxide are involved in chemical reactions with surfaces Controlling air quality is difficult and complex and depends on several interrelated factors
Recommended Standard Values for Museum Atmospheres Pollutant Ozone Sulphur Dioxide Nitrogen Dioxide Recommended Standard 1 ppb < 0.4 ppb < 2.5 ppb Particles (> PM2), SPM Removal at 95% Efficiency
The search for a Threshold In opposition to people, materials accumulate deterioration from any attack, slowly decaying more and more Therefore even small exposures to pollutants will have an effect in the large perspective
THRESHOLD Risk Management NOAEL (No Observed Adverse Effect Level) LOAEL (Lowest Observed Adverse Effect Level)
The parameter NOAEL is now becoming increasing popular in the conservation literature as a standard (e.g. Hatchfield and Tétreault)
From Health Protection we know that: NOAEL is a level that should be considered safe and requires no application of a safety factor to determine a safe intake, based on the most sensitive subgroup. It is the highest tested dose of a substance that has been reported to have no harmful (adverse) health effects. LOAEL is a level that should NOT be considered safe for everyone and may require the application of a safety factor to calculate a safe intake. It is the lowest tested dose of a substance that has been reported to cause harmful (adverse) health effects.
RESPONSE LOAEL Control NOAEL DOSE
Which is the relevance of the NOAEL Concept? Jean Tétreault has shown that the corrosion of lead surfaces occurs at concentrations of acetic acid above 300 ug/m3 (Studies in Conservation 48, 273-250, 2003) However, Jens Glastrup of the National Museum of Denmark has demonstated that this result has been obtained because he was unable to measure a corrosion lower than 25 nm/year
The No Observed Adverse Effect Level concept The highest level of a pollutant that does not produce an adverse effect on a specific chemical or physical characteristic of a material But it should be added in a particular experimental set-up
CNR-IIA Projects funded by EC Project Title Period STEP ENVIRONMENT MIMIC MULTIASSESS Physico chemical parameters, including pollutant interactions affecting the rate of dry deposition of SO2 and other pollutants on CaCO3 surfaces Deposition of gases and particles and their corrosive effects on surfaces of cultural and artistic value inside Museums Microclimate Indoor Monitoring in Cultural Heritage Preservation Model for multi-pollutant impact and assessment of threshold levels for cultural heritage 1991-1994 1994-1997 2001-2004 2002-2005
EVK4-CT-2000-00040 MIMIC: Microclimate indoor monitoring in cultural heritage preservation
Microclimate Indoor Monitoring in Cultural Heritage Preservation Funded by the European Commission Environment Programme Coordinator School of Biological & Chemical Sciences, Birkbeck College, University of London (Dr. Marianne Odlyha) Partners Institute for Atmospheric Pollution of the CNR (National Research Council of Italy). Institute of Applied Physics (IFAC) (National Research Council of Italy) National Trust (England, Wales and Northern Ireland). El Alcazar, Segovia, Spain National Museum of Denmark, Conservation Dept. FOM Institute for Atomic and Molecular Physics, The Netherlands
AIR POLLUTANTS and ARTWORKS The main objective of MIMIC is to provide an early warning damage dosimeter to assess damage In this framework the CNR-IIA aim was to collect pollutant data at several selected sites A diffusive sampling technique was used to determine levels of NO 2, NOx, SO 2, O 3, HONO and HNO 3
EVK4-CT-2000-00040 MIMIC: Microclimate indoor monitoring in cultural heritage preservation
EVK4-CT-2000-00040 MIMIC: Microclimate indoor monitoring in cultural heritage preservation
Analyst Can be used for Indoor-outdoor evaluation Ambient air monitoring Monitoring of industrial sites
Diffusive sampling. How it works Laboratory Analysis A B C The sampler The consists pollutant of is a sampled After exposure at a rate the tube, one end controlled containing by molecular a sampler diffusion is closed and sorbent which without fixes the requiring returned any pump to the pollutant laboratory for analysis
Diffusive Sampling advantages: No pumping systems No specialized people for handling High spatial resolution Low cost Little Silent Not influenced by meteorological parameters disadvantages: Low resolution time
In the overall assessment of the pollutant impact on materials, time weighted averages are more useful than short-term concentrations as they reflect the long-term action of the pollutant
Analyst for Nitrogen Dioxide
Analyst for Nitrogen Oxides
Sampling at at the Uffizi
Natural Ventilation System Air Exchange Forced Use of Doors Infiltration Cracks Unintentional Openings
dc dt i = mic o + S mic i R V Where: C i = Indoor Concentration C o = Outdoor Concentration I = Ventilation rate S = Source strenght R = Decay Rate m = Mixing Factor V =Volume of the room
Assuming: R = KVC i m = 1 Steady-state conditions S = 0 then: C i = I I + K C 0
Uffizi Gallery
Outdoor Pollution at at the Uffizi in in comparison to to the other sites NOx NOx 140 Conc. (ug/m3) 120 100 80 60 Segovia Copenhagen Firenze Sandham NO 2 40 20 0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV 90 Period of sampling 80 NO2 Segovia Copenhagen Conc. (ug/m3) 70 60 50 40 30 Firenze Sandham 20 10 0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV RXV Sampling period
Outdoor Pollution at at the Uffizi in in comparison to to the other sites O3 180 Conc. (ug/m3) 160 140 120 100 80 60 O 3 Segovia Copenhagen Firenze Sandham 40 20 0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV RXV Period of sampling
Outdoor Pollution at at the Uffizi in in comparison to to the other sites 9 SO 2 SO2 Segovia 8 Copenhagen 7 Firenze Conc. (ug/m3) 6 5 4 3 Sandham 2 1 0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV RXV Sampling Period
Outdoor Pollution at at the Uffizi in in comparison to to the other sites 14 HNO 3 HNO 3 Segovia Copenhagen 12 Firenze 10 Sandham Conc. (ug/m3) 8 6 4 2 0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV RXV Sampling Period
Pearson correlation matrix Outdoor SO2 O3 HONO NO2 HNO3 NOX SO2 O3 NOX HNO3 NO2 HONO
Indoor/Outdoor Pollution SO 2 0.5 0.4 Room 9 Room 15 Room 20 I/O Ratio 0.3 0.2 0.1 0.0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV
Indoor/Outdoor Pollution O 3 0.7 0.6 0.5 Room 9 Room 15 Room 20 I/O Ratio 0.4 0.3 0.2 0.1 0.0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV
Indoor/Outdoor Pollution 2.0 NO 2 Room 9 Room 15 Room 20 I/O Ratio 1.0 0.0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV
Indoor/Outdoor Pollution 2.0 NO x Room 9 Room 15 Room 20 I/O Ratio 1.0 0.0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV
Indoor/Outdoor Pollution 0.6 0.5 Nitric Acid Room 9 Room 15 Room 20 I/O Ratio 0.4 0.3 0.2 0.1 0.0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV
Pearson correlation matrix Lippi Room SO2 O3 HONO NO2 HNO3 NOX SO2 O3 NOX HNO3 NO2 HONO
The formation of of HONO in in different rooms 0.6 Room 9 Room 15 Room 20 0.4 HONO/NO 2 Ratio 0.2 0 RI RII RIII RIV RV RVI RVII RVIII RIX RX RXI RXII RXIII RXIV Sampling Period
2NO + H O HONO + HNO 2 2 3 HONO HONO HONO HONO HONO HONO HONO HONO HONO HONO HONO HONO HONO HONO HONO HNO HONO HONO HONO 3 HNO3 HNO3 HNO 3 HNO3 HONO HNO3 S U R F A C E
HONO formation and relative humidity 0.5 65 0.4 0.3 50 HONO/NO 2 Ratio 0.2 0.1 35 RH (%) 0.0 20 RI RII RIII RIV RV RVI RVII RVIII Sampling Period
The I/O ratio of of HONO in in different rooms of of the UFFIZI vs vs British Library 70 60 50 I/O ratio 40 30 20 10 0 British Library Uff. Room 9 Uff. Room 15 Uff. Room 20 Site
CONCLUSIONS (1/2) The technique results suitable for carrying out concentration mapping of a Museum to study the impact of atmospheric pollution The concentrations found indoors for Ozone, Nitrogen Dioxide, Nitrous and Nitric acid represent a risk to the artworks
CONCLUSIONS (2/2) This work confirms that the surface catalysed heterogeneous reaction of water with NO 2 gives equimolecular amounts of HONO and HNO 3 The concentrations of Nitrous and Nitric acids measured indoors are the result of homogeneous and heterogeneous chemistry combined with the characteristics of the surfaces involved
The basic science of conservation of cultural materials is in its infancy (Ralph Mitchell)