Relationship between cement dust exposure and respiratory health in a settlement residing near a cement factory in Chilanga, Zambia

Abstract

There is paucity of information on whether exposure to emissions from a cement factory has pulmonary ill effects on communities residing close to these factories. This study investigated the association of exposure to cement dust and respiratory health effects in a community located near a cement factory. A cross-sectional study, followed by panel study, was conducted in Freedom Compound, a community bordering a cement factory in Chilanga, Zambia and, as control, Bauleni, located 18 km from the cement plant. In the cross-sectional phase, a modified American Thoracic Society questionnaire was administered to 225 and 198 respondents aged 15–59 years to capture symptoms of mucous membrane irritations and respiratory symptoms. For the panel phase, 118 participants were randomly sub-sampled from those participating in the cross-sectional study and followed up for three climatic seasons (cold dry, hot dry and rainy season). In this phase, exposure to cement dust, measured as ambient PM2.5 and PM10 concentrations in both communities and respiratory symptoms together with lung function indices were recorded daily for each participant for 14 consecutive days in each of the seasons. Descriptive statistics and generalized estimating equations (GEE) regression models were used in the analysis. A p-value < 0.05 was considered as statistically significant. A higher proportion of respondents in Freedom, compared to Bauleni, reported signs of mucous membrane irritations: 78.2% vs. 49.9%, 66.9% vs. 29.4% and 73.7% vs. 53.3% for eye, nasal and sinus irritations respectively (p value < 0.001). Respondents from Freedom Compound had higher odds of experiencing the irritations; adjusted odds ratio (OR) 2.50 (95% CI: [1.65, 3.79]), 4.36 (95% CI [2.96, 6.55]) and 1.94 (95% CI [1.19, 3.18]) for eye, nose and sinus mucous irritations respectively. Similarly, respiratory symptoms and diseases were more likely reported in Freedom compared to Bauleni: 5.64 (95% CI [3.63, 8.67]); 3.30 (95% CI [2.04, 5.3), 1.60 (95% CI [1.01, 2.54]); 5.76 (95% CI [2.00, 16.07]); and 5.22 (95% CI [1.75, 15.47]) times more likely to suffer from cough, phlegm production, wheeze, asthma and pneumonia respectively. Mean seasonal concentrations of PM2.5 and PM10 ranges were 2.39 - 24.93 ?g/m3 and 7.03 - 68.28 ?g/m3 respectively for Freedom while PM2.5 and PM10 for Bauleni ranged from 1.69 - 6.03 ?g/m3 and 2.26 - 8.86 ?g/m3 respectively. Overall, the mean FEV1 and FVC predicted percentage for Freedom was six and four percentage points lower than the control. A systematic review revealed that the majority of studies conducted in communities used mostly cross-sectional study design. Most studies reported higher levels of PM2.5 and PM10 in the exposed compared to the controls and demonstrated either a statistically significant difference in the prevalence of respiratory symptoms and reduced pulmonary functions or some degree of association. This review shows that despite showing some degree of association between exposure to cement dust and respiratory ill health, the existing evidence is insufficient to draw firm conclusion mainly because the studies were of low quality. These findings add to existing evidence that there an association between exposure to cement dust emitted from a cement plant and respiratory ill health. Future research, including characterization of air pollutant and source apportionments is required to determine whether the observed excessive respiratory symptoms and lower FEV1 and FVC among participants in the exposed community are due to cement dust emitted from the cement plant.