Respiratory symptoms and lung function patterns in workers exposed to wood smoke and cooking oil fumes (mai suya) in Nigeria

Abstract

Background: 'Mai suya' is a common job in the most northern Nigeria in which there is significant exposures to wood smoke and oil fumes. The respiratory impact of these dual exposures on workers engaged in this work has not been previously documented, hence this study was carried out.

Aim: The aim is to study the prevalence, patterns and respiratory function assessment among this group.

Subject and methods: This is a case controlled study involving mai suya and workers who are not exposed to wood smoke and oil fumes in an occupational setting. All consenting mai suya and matched controls were recruited. Both groups underwent an interviewer administered questionnaire followed by on spot spirometric test measuring forced expiratory volume in one second (FEV1), forced vital capacity (FVC), peak expiratory flow rate (PEFR). Results are presented using descriptive statistics. Chi square was used to test for association between respiratory symptoms and the job categories. Student's t-test was used to compare values of continuous variables. Odd ratios were determined for the risk of respiratory symptoms and exposure to wood smoke and oil fumes.

Results: Both groups are similar in their demographic characters except in their smoking status, so current smokers were excluded from further analysis. The test group had significantly increased occurrence of chest tightness: 59% (19/32), nasal congestion: 37% (12/32), cough: 32% (10/32), and wheeze: 12% (4/32) compared with the control group, odds ratio (OR) 3.1, 95% confidence interval CI (0.1-5.8), P value 0.04, OR 1.2,95% CI (1.04-1.8), P value = 0.02, OR 0.9 95% CI (0.9-1.4), P value = 0.3, and OR 1.2,95% CI (1-1.3), P value = 0.04, respectively. Occurrences of some respiratory symptoms were associated with duration on the job, while a positive family history of asthma is not associated with increased occurrence of symptoms. The mean (SD) FEV1 and FVC were significantly lower among the test group compared with the control group; 2.5L/s (0.55) versus 3.02L/s (0.51), P value = 0.007 and 2.7L (0.7) versus 3.16L (0.51), P value = 0.04.

Conclusion: Mai suya' have increased risk of respiratory symptoms and altered pulmonary functions. There is a need for protective equipment and periodic evaluation.

Keywords: Function; Mai suya; Oil fumes; Pulmonary.