Respiratory Changes due to Long-term Exposure to Urban Levels of Air Pollution: Data Analysis

In: Pulmonary function

13 May 2014

Measurements of Distal Parenchyma (Membranous Bronchioli and Subpleural Areas): The analysis of the distal parenchyma was designed to verify the presence of pathologic changes in the membranous bronchioli. We evaluated the amount of deposition of carbon pigment in the regions of lymphatic drainage: subpleural connective tissue and the axial connective tissue around bronchi and blood vessels. The number of spots in carbon deposition was counted in five randomly selected bronchovascu-lar bundles and in five fields of 100 X along the visceral pleura. The results of the carbon deposition were averaged for each case. The histopathologic alterations of the bronchioli were done as follows: the presence of inflammatory reaction, wall thickening, and secretoiy hyperplasia was scored from 0 (absence) to 3 (maximal intensity) in five randomly selected airways. The results of each histopathologic parameter were averaged for each case.

Data Analysis
The mean and median scores for inflammation, wall thickness, hypersecretion, anthracosis, and gland/wall ratio were compared and tabulated for smokers and nonsmokers and individuals who had lived in high and low pollution areas. Similarly, individual scores and means were compared graphically. To make more formal statistical inferences and to control for other variables while evaluating potential differences in these histopathologic parameters between high and low pollution exposure, multiple regression models were also estimated. The scores of the parameters were regressed on an indicator variable for high and low pollution exposure, plus an indicator variable for smoker vs nonsmoker, number of pack-years smoked, age, sex, and occupational exposure.
Because the measure of anthracosis is simply a measure of deposition of carbon pigment, it may be considered a bioindicator of exposure to fossil fuel combustion related to air pollution or an agricultural process involving burning for harvesting purposes, such as in the sugar cane industry, wood burning, and cigarette smoking. To explore a possible relationship of inflammation, wall thickness, hypersecretion, and glandAvall ratio with anthracosis, individual scores of these parameters were plotted over the anthracosis scores. Furthermore, additional regression models for inflammation, wall thickness, hypersecretion, and gland/wall ratio were estimated with the indicator variable for high air pollution exposure replaced with the mean scores for anthracosis.

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