Abstract
Attempts to determine a workable relationship between visibility and the soiling index of air sampling tapes are described. It is shown that visibility is a function of relative humidity, whereas soiling index is not. Albeit the visibility-soiling index-humidity correlations were significantly different from zero at a high level of confidence, they are not of such quality as to permit good quantitative estimates of soiling index from measurements of visibility and humidity. The reproducibility of soiling index within reasonable limits is questioned, since under nearly identical visibility and humidity conditions the soiling index values vary over a relatively wide range.
