Building materials concentrations

Ores which comprise a variety of minerals are, as a rule, heterogeneous. An ore body is usually named for the most important mineral (s) in the rock, referred to as value minerals, mineral values, or simply values. Some minerals contain metals, which are extracted by concentration and smelting. Other minerals, such as diamond, asbestos (qv), quartz (see Silicon COMPOUNDS), feldspars, micas (see Mica), gypsum, soda, mirabillite, clays (qv), etc, maybe used either as found, with some or no pretreatment, or as stock materials for industrial compounds or building materials (qv) (3). 

Selenium is a vital microelement for people. It has dual properties. Selenium is an essential nutrient at low concentration levels and it becomes toxic at higher concentration levels. Deficiency of selenium results in weakness and hard diseases. Selenium is a building material of many hormones and ferments it neutralizes free radicals, radioactive radicals in organism. The range of selenium safety concentration in food and water is very narrow. The daily normal amount of human consumption of selenium is 10-20 p.g, maximum safe concentration of selenium in water is 5-10 p.g/1. It becomes toxic at 20-30 p.g and bigger content in different objects. 

The requirements on building materials due to air velocities inside the building are generally negligible. However, sometimes the allowed contaminant concentrations can be of such magnitude that moving air may affect surfaces. In such cases it is necessary to use materials with sustainable surfaces. Normally this demand is valid only for the transport of dust-laden air in... 

Contaminant concentrations Dispersal of airborne contaminants such as odors, fumes, smoke, VOCs, etc. transported by these airflows and transformed by a variety of processes including chemical and radiochemical transformation, adsorption, desorption to building materials, filtration, and deposition to surfaces evolution of contaminant concentrations in the individual zones air quality checks in terms of CO2 levels cross-contamination evaluation of zones air quality evaluations in relation to perception as well as health. Methods ate also applicable to smoke control design. 

In COMIS, source or sink strength can be defined as time dependent but not dependent on actual concentrations or temperatures. COMTAM96 includes more sophisticated models such as chemical reactions, adsorption and desorption to building materials, filtration, and deposition to surfaces. 

Acceptable indoor air quality (lAQ) is defined as air in which there are no known contaminants at harmful concentrations as determined by cognizant authorities and with which a substantial majority (80%) of the people exposed do not express dissatisfaction (ASHRAE, 1989). Some of these indoor air contaminants are particulates, vapors, and gases that may be generated by occupants and their activities, building materials, furniture, equipment and appliances present in indoor space, operations and main-... 

A small percentage of the buildings in the United States with indoor radon concentrations in excess of 4 pCi/L can be attributed to building materials. Most of the building material problems have arisen from the use of known radium- or uranium-rich wastes such as aggregate in block or as backfill around houses. None of the houses studied in the U.S. EPA Radon Reduction Demonstration program have had any identifiable problem associated with radon from building materials. 

Building material Ra-226 activity concentration (Bq kg-1) Range and mean Exhalation rate per unit mass and unit Ra-226 activity concentration (Bqh lkg l)/(Bqkg l) Estimated range of exhalation rate frcm typical walls (Bqh l m 2) ++... 

More, H. Radionuclides in building materials, a summary of activity concentrations in samples investigated at the National Institute of Radiation Protection, Report 85-08, National Institute of Radiation Protection, Stockholm (1985) (in Swedish). 

Wolfs, F., Hofstede, H., deMeijer, R.J. and Put, L.W., Measurements of radon-daughter concentrations in and around dwellings in the northern part of the Netherlands a search for the influences of building materials costruction and ventilation. Health Phys, 47 ... 

The decay sequence for Rn-222 is given in Figure 2. Because of the 4 day half-life of Rn-222, it has the time to penetrate through the soil and building materials into the indoor environment. There is some recent evidence that in spite of its short half-life, 55 seconds, Rn-220 can also penetrate into structures in significant amounts (Schery, 1985). However, the data are limited and the extent of the thoron problem is quite uncertain. It is, therefore, the short-lived decay products of radon that are considered to be particularly important in the exposure of the general public and it is these isotopes on which this report will concentrate. 

Decontamination of JACADS will require chemical, mechanical, and thermal processing. The removal of critical structural components and systems from buildings will have to be planned to ensure structural stability. Residuals of any of the agents processed at JACADS (HD, GB, and VX) may be exposed during disassembly activities. These residuals will be harmful to anyone in the immediate area If they are vaporized, airborne agent concentrations could be harmful, so decontamination procedures for equipment, waste streams, and building materials must ensure that agent residues are destroyed, and the destruction must be verified. 

Recent studies have revealed that carbon tetrachloride is also a common contaminant of indoor air. Typical concentrations in homes in several U.S. cities were about 1 pg/m (0.16 ppb), with some values up to 9 pg/m (1.4 ppb) (Wallace 1986). Concentrations in indoor air were usually higher than in outdoor air, indicating that the source of the carbon tetrachloride was building materials or products (pesticides, cleaning agents) inside the home (Wallace 1986 Wallace et al. 1987). Based on 2,120 indoor air samples in the United States, the average concentration of carbon tetrachloride was 0.4 ppb (2.6 pg/M) (Shah and Heyerdahl 1988). However, the median value was 0 ppb, indicating that carbon tetrachloride was not detected in more than half the samples. 

Other sources include building materials such as concrete that are made from the earth s crustal materials and hence can contain significant amounts of uranium and radium (Nazaroff and Nero, 1988). Radon dissolves in water, and hence degassing from household water can also be a source. For example, Osborne (1987) reported that the radon concentration in a bathroom increased by more than two orders of magnitude during a 15-min period that a shower was running. 

The use of building materials, furniture, carpets and household products produces an almost ubiquitous level of volatile organic compounds (VOCs) in indoor air. Several hundred different compounds have been identified in the indoor environment. Since most air pollutants occur in low concentrations of 1-1000 rg/m3, highly sensitive detection methods as well as efficient separation methods are needed to analyze air samples (Barro et al., 2009). 

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