Standards airborne contamination levels

When measurements of airborne contamination levels or other parameters have been made it is necessary to interpret results against a standard. This interpretation will form the basis for the control strategy. In considering the exposure of workers to chemicals two broad options may be presented ... 

NIOSH has developed Guidance on Emergency Responder Personal Protective Equipment for Response to CBRN Terrorism Incidents where the NFPA 1994 Standard sets the performance requirements for protective ensembles used in response to CBRN terrorism incidents. The standard defines three classes of ensembles (Classes 2, 3, and 4) based on the protection required for different hazard types (vapors, liquids, and particulates) and airborne contaminant levels. 

The level of protection that can be provided by a respirator is indicated by the respirator s protection factor (PF). This number, determined experimentally by measuring facepiece seal and exhalation valve leakage, indicates the relative difference in concentration of the concentrations of substances outside and inside the facepiece that can be maintained by the respirator. For example, a PF of 10 for a respirator means that a user could expect to inhale no more than one tenth of the airborne contaminant present. A source of protection factors for various types of atmosphere-supplying and air-purifying respirators can be found in the American National Standards Institute (ANSI) standard ANSI Z-88.2-1980. 

In a conventional laboratory, Adeloju and Bond [42] observed considerable variations when periodically measuring voltammetrically standard solutions of cobalt, nickel, copper, zinc, selenium, and lead owing to the variability of airborne contamination. They stress that the adoption of a blank substraction approach is no more than a futile exercise because of the variability of the analytical blank levels with time. Boutron [43] assessed the effect of air purity on the analysis of a standard solution containing 10 ng/mL of iron. When samples were prepared in an ordinary laboratory environment, values of 20.6 ng/mL were observed Finally, Gretzinger et al. [44] filled carefully cleaned quartz beakers (cross-section, 16 cm volume 20 mL) with 10 mL of 1 M HCl, prepared by subboiling (or nonebullient) distillation [45], deposited them uncovered in an ordinary laboratory on different days, and measured the iron level in the HCl solution. The weather was found to play an important role as a rule, when it is raining the air is essentially more pure than when it is dry. On one dry day, the amount of iron in the 10 mL of 1 M HCl over a periode of 6 hr was up approximately 20 ng, on another up to more than 30 ng. 

Adequate ventilation (natural, mechanical, or respiratory) must be provided for all welding, cutting, brazing, and related operations. Adequate ventilation means enough ventilation so that a person s exposure to hazardous concentrations of airborne contaminants is maintained below the level set by federal standards. 

Few papers on the analysis of PCAs or their measurement in environmental samples have reported on techniques to minimize contamination. PCAs (C10-C13,60-70% Cl) levels ranging from 4 ng g 1 to 25 ngg 1 in sodium sulfate were found in procedural blanks used in sediment extractions [28]. PCAs (C10-C13,60-70% Cl) were also detected in DCM (0.15 pg 1 ) left to evaporate in an open flask overnight it was unclear, however, whether contamination was a result of airborne PCAs or was from the DCM itself [28]. Similar problems have been encountered with airborne PCB contamination of analytical labs [65]. Significant procedural blanks result in higher method detection limits, i. e., the mean plus three times the standard deviation in the background signals from procedural blanks (sodium sulfate) [14,66,67]. 

Who Employees who may be exposed to airborne 4,4 -Methylenedianiline (MDA) at or above its action level or where dermal exposure to MDA can occur. (Note the standard does not apply to finished articles that contain MDA or to materials in any form that contain less than 0.1% MDA by weight or volume.) Also, this standard incorporates by reference 1910.38, 1910.1200, and 1910.134, which have additional training requirements. Also, any person who cleans or launders contaminated protective clothing is to be informed of the hazards of exposure to MDA. In addition, the employer must provide specified information to the physician who is conducting medical surveillance, and the employee is to receive a copy of the physician s written opinion within fifteen days after the employer receives it. 

Exposure standards for airborne chemical contaminants ate usually set somewhat lower than the levels which cause observable effects - that is, a safety factor is built in. 

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