Conservation of Historic Stone Buildings and Monuments (1982) / Chapter Skim
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Measurement of Local Climatological and Air Pollution Factors Affecting Stone Decay
Measurement of Local Climatological and Air Pollution Factors Affecting Stone Decay
Pages 197-210
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From page 197... ...
Throughout the ages, stone has been used as a building material because it lasts longer then wood or other materials. Even the most permanent stone structures are subject to attack by nature, of course, but the typical time scale over which damage occurs from natural Amp rover many Harmon life snans [except when damage is caused ~ v ~ ~ -a rid At- ~ Ivar Tombach is Vice President of Environmental Programs, AeroVironn~ent; Inc., Pasadena, Calif.
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From page 198... ...
, and many of the mechanisms require the existence of foreign materials in the stone or on its surface. These impurities are usually introduced to the stone by wet or dry deposition from the atmosphere, or are the by-products of chemical reactions with these atmospheric materials.
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From page 199... ...
For example, Fassina has studied the effects of environmental conditions on the detenoration of stonework in Venice using daily measurements of meteorological conditions and of some atmospheric pollutants.6 In a few cases where a theoretical or empirical basis has been developed to describe a decay mechanism quantitatively, it may even be possible to predict the behavior and to compare the relative significance of several mechanisms. Chemical reaction rates are in this latter category,9 along with the stresses caused by freezing wateri° and various
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From page 200... ...
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From page 202... ...
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From page 203... ...
Obviously, whenever appropriate meteorological or air pollution data are available from a government, university, or private monitoring station, the use of those data is the most efficient and least expensive way to acquire information. As an example, Winkler has studied mEteorological effects on the deterioration of the National Bureau of Standards test wall using meteorological data from the Washington National Airport.
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From page 205... ...
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From page 206... ...
For qualitative purposes, visibility determinations at a nearby airport may be usable, but such information should be used cautiously since the existence of fog at a specific location depends considerably on the elevation or proximity to a body of water. The urban heat-island effect generally reduces fog in cities, but pollution from a city often increases fog downwind.
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From page 207... ...
Expert advice should be sought for selecting the appropriate shield for use near a wall to avoid reflected radiation. Because of local heating and limited air circulation, the air temperature near the walls of a building could vary from one side of the building to the other.
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From page 208... ...
Ideally, one would like an existing air pollution monitoring station within a kilometer or two of the study site, with no nearby pollution sources to cause the concentrations of SO2 or NOx at the study site to differ from those at the station. Otherwise, air pollutant monitoring becomes an expensive venture, and expert help win certainly be needed to calibrate the instruments.
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From page 209... ...
Polycarbonate filters (Nuclepore) are necessary for electron microscope analyses; nylon filters collect gaseous nitric acid tHNO3)
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From page 210... ...
Continuous ill situ monitoring of ambient particular sulfur using flame photometry and thermal analysis. Atmos.
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