【摘要】 [目的 ]探讨生产场所矽尘环境瞬时浓度 (EIC)与其时间加权平均浓度 (TWA)间的关系。 [方法 ]在铸造厂、耐火材料厂和锡矿同时测定矽尘EIC和TWA。提出理想瞬时浓度的概念 ,基于理想瞬时浓度及其取值集合S的共同框架来分析EIC与TWA两者的关系 ,推导出TWA理论 =μeσ2 / 2 。以该公式将上述 3家厂矿EIC换算为理论TWA ,并与相应TWA实测值比较。 [结果 ]理论与实测TWA间的差别在耐火材料厂和锡矿均无显著性 (t =1.961和t =1.746,均P >0 0 5 ) ,该公式成立 ,而在铸造厂则否 (t=7.772 ,P <0 .0 5 )。 [结论 ]生产性矽尘EIC与TWA之间在多数情况下存在一定的函数关系 ,经TWA理论 =μeσ2 / 2可将EIC转换为TWA ,这对于我国制订粉尘职业接触限值时确定其TWA限值 ,以及对于TWA的上限值容许上移多少这一国际上有争论的问题均有指导作用更多还原

【Abstract】 Objective To study the relationship between the environmental instantaneous concentration(EIC) and time weighted average concentration(TWA) of silica dust in workplaces.[Methods] In a foundry,a factory producing fire-resistant materials and a tin mine,the dust levels in workplances were determined both in EIC and TWA simultaneously. A concept of so-called optimum instantaneous concentration was proposed as a basis to analyze the relationship between EIC and TWA,whereby a formula TWA theor=μe σ 2/2 deduced. By using this formula,measurements of EIC in all the workplaces were converted into theoretical TWA values,which were then compared with the actual values of determined TWA.[Results] There was no significant difference between results(Student t test,P>0.05) obtained from the fire-resistant materials factory and tin mine. But it was not the case for the foundry. [Conclusion] There exists a relationship expressed as TWA theor=μe σ 2/2,between EIC and TWA in most workplaces,which may be helpful in converting EIC into TWA concentrations and in setting the TWA value while working out a dust occupational exposure limit in China and also determining how much should be allowable for TWA excursion limit internationally.更多还原