Bioaerosol Emission From MSW Open Dumpsites And The Impact On Exposure And Associated Health Risks

The activities associated with the open dumping of municipal solid waste emit air pollutants, including bioaerosols that contaminates the air around dumpsites, rendering it unsafe for dumpsite workers and residents living near dumpsites. Quantitative data on the exposure to bioaerosols from open dumpsites are scarce, thus impeding the development of effective interventions that would reduce the risk of respiratory diseases among dumpsite workers and residents living near dumpsites. The specific objectives for this study included (i) to identify the key working areas and activities of the workers at open dumpsites; (ii) to identify the most important groups of local residents that may be affected by contaminated air due to the waste management activities carried out at open dumpsites; (iii) to obtain background information regarding the respiratory health condition of the workers and the local residents in order to determine the extent to which they suffer respiratory diseases that may be related to exposure to the contaminated air from dumpsite; (iv) to measure the concentrations of bioaerosols at key locations on the open dumpsite to determine the impact of different waste management activities and seasonal variations on bioaerosol concentrations; (v) to analyse the bioaerosol data and to compare the ambient concentrations to concentrations at the controls; (vi) to quantify the potential health risk associated with exposure to pathogenic bioaerosols from the open dumpsites using the Quantitative Microbial Risk Assessment (QMRA) tool. A cross sectional respiratory health survey was conducted in the study area between 12th -27th January 2017 with a total 414 respondents (workers = 149, resident = 145 and control = 120). A six-stage Anderson sampler and the SKC button sampler were used to measure ambient bioaerosol concentration and exposure concentration during key activities at the dumpsite respectively. The four bioaerosols indicator groups (total bacteria, gram-negative bacteria, Aspergillus fumigatus and total fungi) measured were expressed as cfu m-3. Using the Markov chain model, the deposition of inhaled bioaerosols in the workers lungs was computed. The infection risk estimates were computed using the beta-Poisson dose response model and the results reported within the QMRA framework. The result of the cross-sectional survey shows that cough was the most reported by the respondents. In all, up to 27% of respondents reported one or more symptoms of cough and phlegm and up to 8.7% reported three or more symptoms (cough, phlegm, asthma etc.). On the dumpsite, while chronic cough particularly affected smokers, it had a prevalence of 38%. Chronic phlegm and asthma was prevalent at 31% and 2% respectively. Only chronic cough and chronic phlegm showed prevalence that were significantly higher that the controls (p 5 years showed was not associated chronic cough, chronic phlegm asthma. Among residents, chronic cough particularly affected the non-smokers and had the prevalence of 31.7%. Chronic phlegm and asthma was prevalent at 28.9% and 8.2% respectively. Only chronic cough and chronic phlegm showed significantly higher prevalence compared to the control (p < 0.001). Daily exposure duration was also associated with chronic cough with odds ratio of 1.2 (95% CI 1.1–1.3, p < 0.001) but not with chronic phlegm and asthma. The frequent visit of a resident to the dumpsite had an associated odds ratio of 3.8 (95% CI 1.6–8.4, p < 0.001), 4 (95% CI 1.1-14.4, p < 0.05) and 6.8 (95% CI 1.3-33, p < 0.01) for chronic cough, chronic phlegm and asthma respectively, when compared to the controls. Only years of work <10 years showed associated with chronic cough with odds ratio 4.2 (95% CI 1.4–12.4, p < 0.01) when compared to the controls. At the 95th percentile, the ambient concentration of total bacteria was 2189 cfu m-3, gram-negative bacteria 2352 cfu m-3, total fungi 824 cfu m-3 and Aspergillus fumigatus 300 cfu m-3, and were significantly higher in magnitude than the control by 2-3 log (p< 0.05). The concentration of bioaerosols at the active operational area was the highest in comparison to the other three sampling locations. However, there were no significant differences in concentration across the four sampling points for total bacteria, gram-negative bacteria and the total fungi. Aspergillus fumigatus, on the other hand, recorded a drastic decrease in concentrations up to 80-81% between the active operational area and the boundary. The particle size distribution shows that the workers were at risk of inhaling air contacting 41%, 46%, 63%, 76% of total bacteria, gram-negative bacteria, total fungi and Aspergillus fumigatus respectively, that were of sizes capable of penetrating deep into the tracheobronchial and the pulmonary region of the lungs, posing a greater human health risk. This study has shown that exposure to bioaerosols were also associated with specific activities undertaken at the dumpsite. Workers were exposed to bioaerosol concentrations up to 106 cfu m-3 during scavenging, waste sorting and site monitoring. These concentrations were 3-log higher than the mean concentration measured in the ambient air. The result shows that on a daily basis, workers were likely inhaling bioaerosols at concentrations ranging from 8.9 × 105 -1.8 × 107 cfu m-3 of total bacteria, 4.0× 105-8.1× 106 cfu m-3 of gram-negative bacteria and 3.29× 105-1.5× 106 cfu m-3 of Aspergillus fumigatus that were of sizes capable of penetrating deep into the tracheobronchial and the pulmonary region of the lungs when undertaking scavenging, waste sorting and site monitoring. These concentrations were higher than expected limit by the UK Environment Agency. The result of the QMRA showed that that the activities at the dumpsite may contribute more to the likelihood of workers developing either respiratory infection or GI infection than anything else. The infection risk from inhaling contaminated air containing spores of Aspergillus fumigatus were in the magnitude of (10-1) all locations and activity types on the dumpsite. However, the risk of infection from ingesting E.coli O157:H7 from ambient exposures across all locations on the dumpsite ranged from 10-3-10-2 for the conservative and 10-4-10-3 for the least conservative of pathogen-indicator ratio. While the risk of infection due to undertaking scavenging, waste sorting and dumpsite monitoring were in the magnitude of 10-1. Overall, this study suggests that the high prevalence of respiratory disease among the workers and the residents are indications of exposure to contaminants in the air from the dumpsite, which includes bioaerosols, as the prevalence were similar among the workers and the residents. The risk estimates show that of infection from bioaerosols were high irrespective the activity the workers undertook at the dumpsite

Exposure to bioaerosols at open dumpsites: A case study of bioaerosols exposure from activities at Olusosun open dumpsite, Lagos Nigeria

Activities associated with the open dumping of municipal solid waste has the potential for greater impact on the environment and public health compared to other forms of waste-to-land treatment of such wastes. However, there is a lack of quantitative data on the exposure to bioaerosols from open dumpsites, hence impeding the development of effective interventions that would reduce the risk of respiratory symptoms among scavengers and waste workers at such dumpsites. This study investigated exposure to bioaerosols at Olusosun open dumpsite, Lagos Nigeria using three methodologies; (1) Conducting a cross-sectional survey on the respiratory health of the population on the dumpsite, (2) Measuring bioaerosol concentrations in the ambient air by measuring four bioaerosols indicator groups (total bacteria, gram-negative bacteria, Aspergillus fumigatus and total fungi) using a Anderson six stage impactor sampler, (3) Measuring activity related exposures to bioaerosols using an SKC button personal sampler. After a cross sectional health survey of 149 participants (waste workers, scavengers, middlemen, food vendors and business owners), smokers reported higher symptoms of chronic cough (21%) and chronic phlegm (15%) compared to non-smokers (chronic cough 15%, chronic phlegm 13%). Years of work > 5 years showed no statistically significant association with chronic phlegm (OR 1.2, 95% CI 0.4–3.4; p > 0.05) or asthma (OR 1.8, 95% CI 0.6–5.2; p > 0.05). At the 95th percentile, the concentration of total bacteria was the highest (2189 CFU/m3), then gram negative bacteria (2188 CFU/m3), total fungi (843 CFU/m3) and Aspergillus fumigatus (441 CFU/m3) after ambient air sampling. A comparison of the data showed that the activity-based sampling (undertaken using body worn personal sampler) had higher bioaerosols concentrations (104 –106 CFU/m3), i.e. 2–3 logs higher than those recorded from static ambient air sampling. Bioaerosol exposure was highest during scavenging activities compared to waste sorting and site supervision. Particle size distributions showed that 41%, 46%, 76% and 63% of total bacteria, gram-negative bacteria, Aspergillus fumigatus and total fungi respectively were of respirable sizes and would therefore be capable of penetrating deep into the respiratory system, posing a greater human health risk. This study has shown that exposure to bioaerosols can be associated with activities undertaken at open dumpsites and may contribute to the high prevalence of the chronic respiratory symptoms among the workers in such environments

Data set associated with Bioaerosol emissions from Open Waste Dumpsites: A Case study of Olusosun Dumpsite, Lagos-Nigeria

Data Set 1: This is the data showing bioaerosols particle size distribution at Olusosun dumpsite at the varoius sampling locations on the dumpsite. Data set 2:This shows the details of the activity based sampling as discussed in the publication and how the final results were derived. Data Set 3: Bioaerosols concentration in the ambient air across the dumpsite. This is shown for Total bacteria, Gram-negative bacteria and Aspergillus fumigatus. Dataset 4: Shows the bioaerosols concentration per location per sampling visit

Quantitative microbial risk assessment (QMRA) of workers exposure to bioaerosols at MSW open dumpsites

The bioaerosol exposure data from the study by Akpeimeh, Fletcher, and Evans (2019) was used to compute the risk of infection from the exposure of dumpsite workers to Aspergillus fumigatus and Escherichia coli O157:H7. A stochastic (Markov Chain) model was used tomodel the transport of the inhaled dose though the human respiratory system and then integrated into the beta-Poisson dose–response model to estimate workers risks of respiratory and gastrointestinal (GI) infection. The infection risk was computed based on workers exposure to E. coli O157:H7 at 10–50% pathogen ingestion rate and pathogen-indicator ratio (P:I) of 1:103 and 1:104, while exposure to A. fumigatus was based solely on the average initial exposure dose. The results showed that after 11 hours of exposure, workers engaged in scavenging, waste sorting, and site monitoring were at risk of respiratory and GI infection in the magnitude of 10−1. However, the risk estimates associated with specific areas of the dumpsite showed that, the risk of GI infection at the active area ranged between 3.23 × 10−3–1.56 × 10−2 and 3.25 × 10−4–1.62 × 10−3; dormant area 2.06 × 10−3–1.01 × 10−2 and 2.09 × 10−4– 1.04 × 10−3; entrance 1.85 × 10−3–9.09 × 10−3 and 1.87 × 10−4–9.27 × 10−4; boundary 1.82 × 10−3–8.82 × 10−3 and 2.09 × 10−4–8.94 × 10−4 for P:I = 1:103 and 1:104 respectively, while the risk of respiratory infection risks were in the magnitude of 10−1 for all four locations. The estimated risk of workers developing respiratory and gastrointestinal infections were high for all activities assessed at the dumpsite