I read with great interest the study by Gupta et al. published in April-June 2022 issue of the Indian Journal of Occupational and Environmental Medicine. By using spirometry, Gupta et al. found that all the parameters of pulmonary function tests (PFTs) were significantly decreased among hairdressers in Gangtok, India, and almost all the differences were statistically significant. They concluded that occupational exposure of hairdressers imposes the risk of derangement of pulmonary function and the development of respiratory symptoms. Gupta et al. mentioned three study limitations, namely a small sample size, lack of pre-employment pulmonary function status, and not measuring the concentration of chemicals in the salon environment. We believe that the following methodological limitation is relevant. The interpretation of PFTs parameters is usually based on comparisons of data with reference (predicted) values based on healthy subjects with similar anthropometric and racial characteristics. Hence, spirometric prediction equations (SPEs) have been constructed for certain populations. India has already formulated SPEs in adults. In the study methodology, Gupta et al. did not mention which SPEs were utilized to assess the readings of various PFTs parameters. This limitation, therefore, could additionally bring into question the rightness of the study findings.
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