Peak expiratory flow rate variation and occupational airway obstruction among workers in a plastic manufacturer in Benin

Introduction
Occupational asthma is an occupational lung disease most common in developed countries. In Africa, particularly in Benin there is insufficient data to assess its prevalence. Conditions and working environment with all the dust and molecules which are bound workers are still capable of inducing occupational asthma or exacerbate asthma pre existent. The objective of this study was to evaluate the peak expiratory flow (PEF) among workers exposed to chemicals dust in a plastics manufacturing industry in Benin.

Methods
A cohort study was conducted for four weeks in March 2011. It has involved 70 employees who were grouped into 44 exposed to toxic dust and 26 unexposed to the dust. All patients who had a known history of lung disease and smokers were not included in this study. A questionnaire was administered and PEF were carried out outside of work, during work and after work.

Results
The mean age was respectively 30 ± 7 and 33 ± 9 years in the exposed vs. unexposed (p = 0.163). The length of service is 37 ± 25 months in the exposed against 30 ± 32 months in the unexposed (p = 0.154). Average PEF outside of work is 478 ± 89 and 512 ± 59 respectively in the exposed and unexposed (p = 0.032). During operation the average PEF is respectively of 440 ± 76 and 483 ± 52 in the exposed and unexposed (p = 0.045). By the end of work the average PEF was not statistically different (p = 0.079).Reduction of 95% in PEFR was found in 15,8% of exposed workers as against 3,8% among unexposed with RR = 1.47 (95% CI: 1.05-2.04).

Discussion
There is a higher risk of developing airway obstruction in workers exposed to toxic dust in this plastic industry. There is so a need to strengthen prevention.