Ambient concentration levels

It should be noted that estimation errors of 50 percent or 100 percent are not unduly large for airborne asbestos measurements. For example, the estimate of a typical ambient concentration level may be 2 nanograms per cubic meter. The bounds for a 100 percent error would be 1 and 4. Although there is no absolute health... 

Evidence has grown over the last decade, that urban airborne particles at ambient concentration levels common in many cities in Europe, America and Asia exert adverse effects on human health. Short- or long-term exposure to particulate matter (measured as PMio or PM2.5) is associated with an increase risk of cardiovascular and respiratory morbidity and mortality. Collectively the toxicological and epidemiological studies provide sufficient evidence that a causal relationship is likely to exist between exposure to ambient concentrations of PMjo or PM2.5 and specific human morbidity (exacerbation of chronic bronchitis, asthma or coronary heart disease) and premature deaths. 

Taketani, F., Kanaya, Y., Akimoto, H. Kinetics of heterogeneous reactions of HO2 radical at ambient concentration levels with (NH4) 2SO4 and NaCl aerosol particles. J. Phys. Chem. A 112, 2370-2377 (2008)... 

The terms ambient air, ambient air pollution, ambient levels, ambient concentrations, ambient air monitoring, ambient air quality, etc. occur frequently in air pollution parlance. The intent is to distinguish pollution of the air outdoors by transport and diffusion by wind (i.e., ambient air pollution) from contamination of the air indoors by the same substances. 

NR = No index values reported at concentration levels below those specified by "alert level" criteria (Table 5-1). Annual primary National Ambient Air Quality Standard. 

Criteria stipulate conditions of exposure and may refer to sensitive population groups or to the joint effects of several pollutants. Air quality criteria are descriptive. They describe effects that can be expected to occur wherever the ambient air level of a pollutant reaches or exceeds a specific concentration for a particular time period. Criteria will change as new information becomes available. 

Exposure to sulfur dioxide in the ambient air has been associated with reduced lung function, increased incidence of respiratory symptoms and diseases, irritation of the eyes, nose, and throat, and premature mortality. Children, the elderly, and those already suffering from respiratory ailments, such as asthmatics, are especially at risk. Health impacts appear to be linked especially to brief exposures to ambient concentrations above 1,000 ixg/in (acute exposures measured over 10 minutes). Some epidemiologic studies, however, have shown an association between relatively low annual mean levels and excess mortality. It is not clear whether long-... 

AAC = acceptable ambient concentration ACGIH = American Conference of Governmental Industrial Hygienists ADEQ = Arizona Department of Environmental Quality SNA = Bureau of National Affairs CDC = Center for Disease Control CERCLA = Comprehensive Environmental Response, Compensation, and Liability Act CFR = Code of Federal Regulations DNR = Department of Natural Resources DWEL = drinking water equivalent level ... 

Another study found that trichloroethylene can be absorbed from the atmosphere by foods and concentrated over time, so that acceptable ambient air levels may still result in food levels which exceed acceptable limits (Grob et al. 1990). The authors estimated that in order to limit food concentrations of trichloroethylene to 50 pg/kg (the maximum tolerated limit for food halocarbons in Switzerland), the level in surrounding air should not exceed 38.5 pg/m (0.007 ppm). Since the accepted levels found near emission sources are often far above this limit, foods processed or sold near these sources may routinely exceed the tolerated trichloroethylene concentration, thus making the setting of air emission standards problematic. It is also noteworthy that the limits recommended by Grob et al. (1990) exceed acceptable ambient air concentrations for many regions of the United States (see Chapter 7). 

Environmental Fate. Having characterized the entry of materials into the environment, we move into the second step of our procedure. The goal at this stage of analysis is to define ambient concentration of the material or its products in areas of concern for receptor (e.g., people, materials or ecosystem components) exposure. A family of computer simulation models has been developed for calculating the ambient levels of a... 

For acute releases, the fault tree analysis is a convenient tool for organizing the quantitative data needed for model selection and implementation. The fault tree represents a heirarchy of events that precede the release of concern. This heirarchy grows like the branches of a tree as we track back through one cause built upon another (hence the name, "fault tree"). Each level of the tree identifies each antecedent event, and the branches are characterized by probabilities attached to each causal link in the sequence. The model appiications are needed to describe the environmental consequences of each type of impulsive release of pollutants. Thus, combining the probability of each event with its quantitative consequences supplied by the model, one is led to the expected value of ambient concentrations in the environment. This distribution, in turn, can be used to generate a profile of exposure and risk. 

Matthews RD. 1980. Estimated permissible levels, ambient concentrations, and adverse effects of the nitrogenous products of combustion the cyanides, nitroolefins, and nitroparaffins. Journal of Combustion Toxicology 7 157-172. 

To protect humans and other mammals, proposed air-quality criteria range from 0.01 to less than 1.0 mg/m3 for metallic nickel and slightly soluble nickel compounds, 0.015-0.5 mg/m3 for water soluble nickel compounds, and 0.005 to 0.7 mg/m3 for nickel carbonyl (Table 6.10). Inhalation of nickel subsulfide concentrations (0.11 to 1.8 mg Ni/m3) near the current threshold limit value of 1 mg Ni/m3 can produce detrimental changes in the respiratory tract of rats after only a few days of exposure (Benson et al. 1995). Additional animal studies are recommended to identify minimally effective inhalation exposure levels for the various nickel compounds (USPHS 1993). Continued monitoring of nickel refining, nickel-cadmium battery manufacture, and nickel powder metallurgy installations is recommended because ambient air levels of bioavailable nickel at these... 

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