Occupational hygiene in terms of volatile organic compounds (VOCs) and bioaerosols at two solid waste management plants in Finland

Review of bioaerosols from different sources and their health impacts

The emission of bioaerosols in the ambient atmosphere from different sources is a cause of concern for human health and the environment. Bioaerosols are a combination of biotic matter like microbes and pollens. The present review emphasizes the understanding of various sources of bioaerosols (industries, municipal solid waste, and medical facilities), their components, and their impact on human health. The study of bioaerosols is of great importance as large numbers of people are estimated to be exposed on the global scale. Bioaerosols exposure in different work environments results in health issues such as infectious diseases, allergies, toxic effects, and respiratory problems. Hence, extensive research is urged to establish an effective assessment of bioaerosols exposure in the workplace, risks involved, distribution, and validation. The present review is intended to explore the relationship between bioaerosols exposure to the atmosphere and its impacts on human health. Some of the preliminary findings, based on our analysis of bioaerosols arising from municipal solid waste at a landfill site and a waste transfer station in Hyderabad, India, are also discussed herein.

The use of gas chromatography combined with chemical and sensory analysis to evaluate nuisance odours in the air and water environment

Varieties of gas chromatography (GC) combined with chemical detection (CD) and sensory analysis at the odour detection port (ODP) for the evaluation of environmental odorants has steadily increased in application and sophistication; this has given rise to a plethora of techniques that cater to specific tasks. With this diversity of approaches in mind, there is a need to assess the critical points at which these approaches differ, as well as likely risks and factors that may affect them. These critical points explained within this review include sample preparation, GC separation techniques (with associated co-elution risks), how the elute is separated between CD and sensory analysis, the type of CD, the type of sensory analysis (with particular attention paid to its factors and guidelines), integrative data techniques, as well as how that data may be used. Additionally, this review provides commentary on the current state of the research space and makes recommendations based on how these analyses should be reported, the standardisation of nomenclature, as well as the impediments to the future goals of this research area. By careful consideration of the critical points of varying analytical processes and how best to communicate these findings, the quality of output within this area will improve. This review provides a benchmark for how GC-CD/sensory analysis should be undertaken and reported.

Health symptoms, inflammation, and bioaerosol exposure in workers at biowaste pretreatment plants

Biowaste pretreatment plants have been built within the last years in Denmark in order to recycle pre-sorted biowaste from houses, restaurants, and industry. We investigated the association between exposure and health at six biowaste pretreatment plants (visited twice) across Denmark. We measured the personal bioaerosol exposure, took blood samples, and administered a questionnaire. Thirty-one persons participated, 17 of them twice, resulting in 45 bioaerosol samples, 40 blood samples, and questionnaire answers from 21 persons. We measured exposure to bacteria, fungi, dust, and endotoxin, the total inflammatory potential of the exposures, and serum levels of the inflammatory markers serum amyloid A (SAA), high sensitivity C-reactive protein (hsCRP), and human club cell protein (CC16). Higher exposures to fungi and endotoxin were found for workers with tasks inside the production area compared to workers with main tasks in the office area. A positive association was found between the concentration of anaerobic bacteria and hsCRP and SAA, whereas bacteria and endotoxin were inversely associated with hsCRP and SAA. A positive association between hsCRP and the fungal species Penicillium digitatum and P. camemberti were found, whereas an inverse association between hsCRP and Aspergillus niger and P. italicum were found. Staff with tasks inside the production area reported more symptoms of the nose than those working in the office area. To conclude, our results indicate that workers with tasks inside the production area are exposed to elevated levels of bioaerosols, and that this may affect workers' health negatively.

Microbial contamination in waste collection: Unveiling this Portuguese occupational exposure scenario

Previous studies anticipated that microorganisms and their metabolites in waste will increase as a consequence of a decreased collection frequency and due to differences in what kind of waste is bagged before collection leading to an increased exposure of workers handling the waste. This study aim was to investigate the microbial contamination present in the waste collection trucks (WCT) and in the support facilities (waste collection station - WCS). It was applied a multi-approach protocol using active (air sampling by impingement and impaction) and passive (surface swabs, electrostatic dust cloths and settled dust) sampling methods. The screening of azole-resistance, the investigation of mycotoxins and the assessment of the elicited biological responses in vitro were also carried out aiming recognizing the possible health effects of waste collection drivers. SARS-CoV-2 detection was also performed. In WCS only air samples had contamination in all the four sampling sites (canteen, operational removal core, operational removal center, and administrative service). Among all the analyzed matrices from the WCT a higher percentage of total bacterial counts and Gram-was detected in swabs (66.93%; 99.36%). In WCS the most common species were Penicillium sp. (43.98%) and Cladosporium sp. (24.68%), while on WCT Aspergillus sp. (4.18%) was also one of the most found. In the azole resistance screening Aspergillus genera was not observed in the azole-supplemented media. SARS-CoV-2 was not detected in any of the environmental samples collected, but Aspergillus section Fumigati was detected in 5 samples. Mycotoxins were not detected in EDC from WCS, while in WCT they were detected in filters (N = 1) and in settled dust samples (N = 16). In conclusion, our study reveals that a comprehensive sampling approach using active and passive sampling (e.g. settled dust sampling for a representative mycotoxin evaluation) and combined analytic methods (i.e., culture-based and molecular) is an important asset in microbial exposure assessments. Concerning the waste collection exposure scenario, the results of this study unveiled a complex exposure, particularly to fungi and their metabolites. Aspergillus section Fumigati highlight the significance of targeting this section in the waste management industry as an indicator of occupational health risk.

Green Manufacturing of Flexible Sensors with a Giant Gauge Factor: Bridging Effect of CNT and Electric Field Enhancement at the Percolation Threshold

Toxic organic solvents are commonly used to disperse nanomaterials in the manufacturing of flexible conductive composites (e.g., graphene-PDMS). The dry-blended method avoids toxic organic solvent usage but leads to poor performance. Here, we proposed an innovative manufacturing method by adapting the traditional dry-blended method, including two key steps: minor CNT bridging and high-frequency electric field enhancement at the percolation threshold of graphene-PDMS. Significant improvement was achieved in the electrical conductivity (1528 times), the giant gauge factor (>8767.54), and the piezoresistive strain range (30 times) over the traditional dry-blended method. Further applications in measurements of culturing rat neonatal cardiomyocytes and mouse hearts proved that the proposed method has great potential for the manufacturing of nontoxic flexible sensors.

Microbiological and toxicological hazard assessment in a waste sorting plant and proper respiratory protection

Even though biological hazards in the work environments related to waste management were the subject of many scientific works, the knowledge of the topic is not extensive. This study aimed to conduct a comprehensive assessment of microbiological and toxicological hazards at the workstations in a waste sorting plant and develop guidelines for selecting filtering respiratory protective devices that would consider specific workplace conditions. The research included the assessment of quantity (culture method), diversity (high-throughput sequencing), and metabolites (endotoxin - gas chromatography-mass spectrometry; secondary metabolites - liquid chromatography tandem-mass spectrometry) of microorganisms occurring in the air and settled dust. Moreover, cytotoxicity of settled dust against a human epithelial lung cell line was determined with an MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. The research was performed in a waste sorting plant (Poland; 240,000 tons waste/year) at six workstations: two feeders, two pre-sorting cabins, secondary raw material press and organic fraction waste feeder for composting. The total dust concentration at tested workstations varied from 0.128 mg m^-3 to 5.443 mg m^-3. The number of microorganisms was between 9.23 × 10⁴ CFU m^-3 and 1.38 × 10⁵ CFU m^-3 for bacteria and between 1.43 × 10⁵ CFU m^-3 and 1.65 × 10⁵ CFU m^-3 for fungi, which suggests high microbial contamination of the sorting facility. The numbers of microorganisms in the air correlated very strongly (R² from 0.70 to 0.94) with those observed in settled dust. Microorganisms representing Group 2 biological agents (acc. to Directive, 2000/54/EC), including Corynebacterium spp., Pseudomonas aeruginosa, Staphylococcus aureus, and others potentially hazardous to human health, were identified. The endotoxins concentration in settled dust ranged from 0.013 nmol LPS mg^-1 to 0.048 nmol LPS mg^-1. Seventeen (air) and 91 (settled dust) secondary metabolites characteristic, e.g., for moulds, bacteria, lichens, and plants were identified. All dust samples were cytotoxic (IC₅₀ values of 8.66 and 56.15 mg ml^-1 after 72 h). A flowchart of respiratory protective devices selection for biological hazards at the workstations in the waste sorting plant was proposed based on the completed tests to help determine the right type and use duration of the equipment.

In Vitro Systems for Toxicity Evaluation of Microbial Volatile Organic Compounds on Humans: Current Status and Trends

Microbial volatile organic compounds (mVOC) are metabolic products and by-products of bacteria and fungi. They play an important role in the biosphere: They are responsible for inter- and intra-species communication and can positively or negatively affect growth in plants. But they can also cause discomfort and disease symptoms in humans. Although a link between mVOCs and respiratory health symptoms in humans has been demonstrated by numerous studies, standardized test systems for evaluating the toxicity of mVOCs are currently not available. Also, mVOCs are not considered systematically at regulatory level. We therefore performed a literature survey of existing in vitro exposure systems and lung models in order to summarize the state-of-the-art and discuss their suitability for understanding the potential toxic effects of mVOCs on human health. We present a review of submerged cultivation, air-liquid-interface (ALI), spheroids and organoids as well as multi-organ approaches and compare their advantages and disadvantages. Furthermore, we discuss the limitations of mVOC fingerprinting. However, given the most recent developments in the field, we expect that there will soon be adequate models of the human respiratory tract and its response to mVOCs.

Occupational exposure to anaerobic bacteria in a waste sorting plant

The study focused on exposure assessment to bacterial aerosols and organic dust in waste sorting plant. Samples were collected at different workplaces of waste sorting cycle i.e.: waste press, reloading area, loading of conveyor belt, sorting cabin, sorting hall, and control room. A quantitative analysis of aerobic and anaerobic bacteria was supplemented by qualitative analysis of anaerobic biota with the use of culture-based methods and biochemical tests. In addition, inhalable dust concentrations were also evaluated. To confirm the presence of Clostridium genus, the PCR reaction with specific primers (Chis150f and ClostIr) was performed. The average concentration of total bacteria in waste sorting plant was 4347 CFU m^-3 (SD = 2439), of which 66% were anaerobic strains (2852 CFU m^-3; SD = 2127). It was found that about 24% of anaerobic bacteria belonged to Clostridium genus (682 CFU m^-3; SD = 633). The highest contamination with anaerobic bacteria was observed near the waste reloading plant (3740 CFU m^-3), and the lowest in the control room (850 CFU m^-3). The average concentration of inhalable dust in the waste sorting plant was 0.81 mg m^-3 (SD = 0.59). The correlation analysis showed that the presence of anaerobic bacteria, including clostridia was significantly determined by the microclimate parameters. Qualitative analysis showed the presence of 16 anaerobic species belonging to 9 genera, of which Actinomyces, Clostridium, and Gemella were present at all workplaces. The molecular analysis confirmed the presence of Clostridium genus in both bioaerosol and settled dust samples.Implications: The study showed that anaerobic bacteria should be taken into account as an important component of this microbiota when assessing the exposure of waste sorting workers to biological agents. However, future studies should investigate more precisely how the composition of sorted waste as well as the season can affect the diversity of anaerobic bacteria in this working environment. More attention should be paid to regular cleaning of equipment surfaces in the plant, as deposited organic dust is an important reservoir of anaerobic bacteria, including those of a potentially pathogenic nature.

Bioaerosol Exposure and in vitro Activation of Toll-like Receptors in a Norwegian Waste Sorting Plant

Background

The global shift toward greener societies demands new technologies and work operations in the waste-management sector. However, progressive industrial methods do not necessarily consider workers’ health. This study characterized workers' exposure to bioaerosols and investigated the bioaerosols’ potential to engage the immune system in vitro.

Methods

Full shift personal aerosol sampling was conducted over three consecutive days. Dust load was analyzed by gravimetry, fungal and actinobacterial spores were analyzed by scanning electron microscopy, and endotoxin by limulus amebocyte lysate (LAL) assay. In vitro exposure of HEK cells to airborne dust samples was used to investigate the potential of inducing an inflammatory reaction.

Results

The total dust exposure level exceeded the recommended occupational exposure limit (OEL) of 5.0 mg/m³ in 3 out of 15 samples. The inhalable endotoxin level exceeded the recommended exposure level by a 7-fold, whereas the fungal spore level exceeded the recommended exposure level by an 11-fold. Actinobacterial spores were identified in 8 out of 14 samples. In vitro experiments revealed significant TLR2 activation in 9 out of 14 samples vs. significant TLR4 activation in all samples.

Conclusion

The present study showed that the dust samples contained potentially health-impairing endotoxin, fungi, and actinobacterial levels. Furthermore, the sampled dust contained microbial components capable of inducing TLR activation and thus have the potential to evoke an inflammatory response in exposed individuals.

One-year follow-up of microbial diversity in bioaerosols emitted in a waste sorting plant in France

Bioaerosols emitted in waste sorting plants (WSP) can induce some adverse health effects on the workers such as rhinitis, asthma and hypersensitivity pneumonitis. The composition of these bioaerosols is scarcely known and most of the time assessed using culture-dependent methods. Due to the well-known limitations of cultural methods, these biodiversity measurements underestimate the actual microbial taxon richness. The aim of the study was to assess the airborne microbial biodiversity by using a sequencing method in a French waste sorting plant (WSP) for one year and to investigate the main factors of variability of this biodiversity. Static sampling was performed in five areas in the plant and compared to an indoor reference (IR), using closed-face cassettes (10 L.min^-1) with polycarbonate membranes, every month for one year. Environmental data was measured (temperature, relative humidity). After DNA extraction, microbial biodiversity was assessed by means of sequencing. Bacterial genera Staphylococcus, Streptococcus, Prevotella, Lactococcus, Lactobacillus, Pseudomonas and fungal genera Wallemia, Cladosporium, Debaryomyces, Penicillium, Alternaria were the most predominant airborne microorganisms. Microbial biodiversity was different in the plant compared to the IR and seemed to be influenced by the season.

Occupational exposure of health care personnel to SARS-CoV-2 particles in the intensive care unit of Tehran hospital

The outbreak of SARS-CoV-2 (COVID-19) has attracted much attention to study its possible presence and airborne transmission. The possibility of COVID-19 airborne transmission in indoor environments is debatable. The present study examined the concentration of viral RNA-containing particles produced directly or indirectly by breathing or coughing of confirmed COVID-19 patients or by carriers without symptoms. Some studies do not accept this method of transmission (COVID-19 airborne transmission). The present study aimed to measure the possible exposure of health care personnel to SARS-CoV-2 particles that may have been suspended in the air to respond to the hypothesis of COVID-19 airborne transmission. Airborne particle sampling was performed using impingement method based on NIOSH (chapter BA) and ASHRAE. Selection of sampling sections was in line with the WHO guidelines. The samples were analyzed using RT-PCR technique. Based on the given results, airborne particles of COVID-19 may present in the air and affect the health of hospital personnel. In fact, the analysis of gene expression in ambient conditions and thereby aerosol transmission of SARS-CoV-2 through air is possible and may lead to occupational exposure of health care personnel. Furthermore, it was found that airborne emission of COVID-19 through the breathing zone of patients, particularly in ICU wards with confirmed cases of COVID-19, may be higher than in other ICU wards. Also, the demonstrated results showed that there is a possibility of reaerosolization (reintroduction) of previously airborne SARS-CoV-2 particles into the atmosphere due to health care personnel frequently walking between different wards and stations of ICU.

The concentration of BTEX compounds and health risk assessment in municipal solid waste facilities and urban areas

In this study, human exposure to benzene, toluene, ethylbenzene, xylenes (BTEX), along with their respective risk assessment is studied in four major units (n = 14-point sources) of the largest municipal solid waste management facilities (MSWF) in Iran. The results were compared with four urban sites in Tehran, capital of Iran. Workers at the pre-processing unit are exposed to the highest total BTEX (151 μg m^-3). In specific, they were exposed to benzene concentrations of 11 μg m^-3. Moreover, the total BTEX (t-BTEX) concentrations measured over the conveyor belt was 198 μg m^-3 at most, followed by trommel (104), and active landfills (43). The mean concentration of ambient t-BTEX in Tehran is 100 μg m^-3. On average, xylenes and toluene have the highest concentrations in both on-site and urban environments, with mean values of 24 and 21, and 41 and 37 μg m^-3, respectively. Even though the non-carcinogenic risk of occupational exposure is negligible, BTEX is likely to increase the chance of carcinogenic risks (1.7E-05) for workers at the pre-processing unit. A definite carcinogenic risk of 1.3E-04, and non-carcinogenic effect, of HI = 1.6 were observed in one urban site. With the exception of the pre-processing unit, the citizens of Tehran had higher exposure to BTEX. Overall, BTEX concentrations in the largest MSWF of Iran remains an issue of public health concern.

Aspergillus spp. presence on mechanical protection gloves from the waste sorting industry

The organic material present on waste sorting units serve as a substrate for different microorganisms, increasing workers' exposure to Aspergillus spp. This study intends to assess the Aspergillus spp. contamination on Mechanical Protection Gloves (MPG) from different workstations and understand the role of MPG in workers' exposure to these genera. Sixty-seven used MPG were collected from different workstations and extracts were seeded on malt extract agar (MEA) supplemented with chloramphenicol (0.05%) and dichloran glycerol (DG18). The same extracts were used for the molecular detection of fungal species/strains, with reported toxigenic potential, namely Aspergillus sections (Circumdati, Flavi, Fumigati, and Nidulantes). Among Aspergillus spp., the sections with the highest prevalence on MEA were Nigri (88.29%) and Fumigati (8.63%), whereas on DG18 were Nigri (31.79%) and Circumdati (30.77%). Aspergillus section Circumdati was detected in 22 MPG samples by RT-PCR (32.84%), Fumigati in 59 samples (88.06%), Nidulantes in 61 samples (91.05%), and Flavi in 6 samples (8.96%). It was showed that, even with daily replacement, MPG presented Aspergillus spp. contamination. Thus, a more regular replacement of MPG and the adoption of complementary hygienic procedures by workers are critical to guarantee workers' protection in this occupational environment.

Exposure to endotoxins and respiratory health in composting facilities

The impact of bioaerosols in municipal solid waste management is nowadays identified as a growing health concern worldwide. In this study, exposure to endotoxin in composting facilities and its association with lung function and clinical symptoms was investigated in Tehran municipal solid waste management complex (Aradkooh) as one of the largest solid waste management facilities in the Middle East. Airborne endotoxins were collected between June and July 2019 and the concentrations were determined by Limulus Amebocyte Lysate (LAL) method. Healthy workers with no history of respiratory disease were recruited and data on clinical symptoms (cough, phlegm, wheezing, dyspnea, fatigue, headache, eye irritation, runny nose, runny eyes, and sore throat) was obtained by the modified American Thoracic Society questionnaire, and spirometric measurement was performed by an expert. The binary logistic regression test was used and adjusted for confounding variables. The results didn't show any difference in lung function parameters (FEV₁, FVC, FEV₁/FVC, PEF, FEF_25-75%), and most of the respiratory symptoms despite a relatively high difference in the concentration of endotoxin observed in air samples of different locations. Only the increased risk of cough (OR 10.5, 95% CI: 2.4 to 44.8 in the moderately exposed group and 7.8, 95% CI: 1.6 to 39.1 in highly exposed ones), fatigue (OR 3.7, 95% CI: 1.2 to 11.7), and headache (OR 6.02, 95% CI: 1.4 to 24.5) were found in the exposed groups compared to controls after adjusting for age, active and passive smoking. However, findings of the study might be underestimated due to some issues including healthy worker effect, intra and intersubject variability, and self-reporting bias, thereby the results should be interpreted with caution. Although we did not find any relationship, due to the high concentrations of endotoxins observed in some sites, it is recommended to consider some possible prevention measures such as using personal protective equipment to reduce the exposure of workers at an acceptable level.

Assessment of airborne particles and bioaerosols concentrations in a waste recycling environment in Brazil

This study aims to assess the concentrations of size-fractioned particle mass (PM_1.0, PM_2.5, PM_4.0, PM₁₀) and number (PNC_0.3, PNC_0.5, PNC_1.0, PNC_2.5), bacteria, and fungi in a Materials Recycling Facility (MRF) in Brazil. The measurements were performed inside the waste processing shed (P1) and in the outdoor environment (P2) during working days in winter and spring of 2017, and summer of 2019. A total of 2,400 min of PM, 1,440 min of PNC, and 216 samples of bioaerosols were collected in the morning and afternoon. P1 has the strongest air contamination with mean values of 475.5 ± 563.7 µg m⁻³ for PM₁₀, 58.6 ± 36.0 cm⁻³ for PNC_0.3, 1,088.8 ± 825.2 colony-forming units per cubic meter (CFU m⁻³) for bacteria, and 2,738.3 ± 1,381.3 CFU m⁻³ for fungi. The indoor/outdoor ratios indicated the large influence of indoor sources due to the activities performed inside P1 that promote the generation and resuspension of pollutants. Gram-positive bacteria dominated with 58.6% of indoor samples. Overall, our results show a critical indoor air quality situation in a Brazilian MRF, which may cause several health risks for waste pickers. Finally, we call attention to the lack of occupational exposure limits for bioaerosols in industrial workplaces and mainly in MRFs.

Application of activated sludge for odor control in wastewater treatment plants: Approaches, advances and outlooks

Odors from wastewater treatment plants (WWTPs) have attracted extensive attention and stringent environmental standards are more widely adopted to reduce odor emissions. Biological odor treatment methods have broader applications than the physical and chemical counterparts as they are environment-friendly, cost-effective and generate low secondary wastes. The aqueous activated sludge (AS) processes are among the most promising approaches for the prevention or end-of-pipe removal of odor emissions and have the potential to simultaneously treat odor and wastewater. However, AS deodorization biotechnologies in WWTPs still need to be further systematically summarized and categorized while in-depth discussions on the characteristics and underlying mechanisms of AS deodorization process are still lacking. Recently, considerable studies have been reported to elucidate the microbial metabolisms in odor control and wastewater treatment. This paper reviews the fundamentals, characteristics, advances and field experiences of three AS biotechnologies for odor treatment in WWTPs, i.e., AS recycling, microaeration in AS digester and AS diffusion. The underlying deodorization mechanisms of typical odors have been revealed through the summary of recent advances on multi-element conversions, metabolic interactions of bacteria, microscopic characterization and identification of functional microorganisms. Future research aspects to advance the emerging deodorization AS process, such as deodorization mechanisms, simultaneous odor and water treatment, synergistic treatment with other air emissions, are discussed.

Recent Advances in Monitoring, Sampling, and Sensing Techniques for Bioaerosols in the Atmosphere

Bioaerosols in the form of microscopic airborne particles pose pervasive risks to humans and livestock. As either fully active components (e.g., viruses, bacteria, and fungi) or as whole or part of inactive fragments, they are among the least investigated pollutants in nature. Their identification and quantification are essential to addressing related dangers and to establishing proper exposure thresholds. However, difficulties in the development (and selection) of detection techniques and an associated lack of standardized procedures make the sensing of bioaerosols challenging. Through a comprehensive literature search, this review examines the mechanisms of conventional and advanced bioaerosol detection methods. It also provides a roadmap for future research and development in the selection of suitable methodologies for bioaerosol detection. The development of sample collection and sensing technology make it possible for continuous and automated operation. However, intensive efforts should be put to overcome the limitations of current technology as most of the currently available options tend to suffer from lengthy sample acquisition times and/or nonspecificity of probe material.

Malodorous gases production from food wastes decomposition by indigenous microorganisms

Volatile organic compounds (VOCs) produced during the degradation of food wastes may harm to the health of people and create annoyance in adjacent communities. In this work, the VOCs emitted from the decomposition food wastes including fruit, meat and vegetable, and their microbial communities were measured in three individual 57-L reactors for 61 days. Total of 232.8, 373.5, and 191.1 μg·kg^-1·h^-1 VOCs with oxygenated VOCs (57.6%), volatile organic sulfur compounds (VOSCs, 58.6%) and VOSCs (54.9%) as the main group were detected during fruit, meat and vegetable fermentation, respectively. 2-Butanone (55.1%) and ethyl acetate (13.8%) were the two most abundant VOCs from fruit wastes, while dimethyl sulfide (68.0 and 26.6%) and dimethyl disulfide (89.2 and 10.1%) were in vegetable and meat wastes. The predominant Firmicutes represented 93.0-99.9% of the bacterial communities of meat decomposition, while Firmicutes and Proteobacteria were the dominant phyla throughout the fruit digestion process. Proteobacteria (16.9%-83.6%) was the dominant phylum in vegetable wastes, followed by Bacteroidetes, Firmicutes, and Actinobacteria. Malodorous VOCs emissions were highly affected by microbial activity, the abundant Weissella, Leuconostoc and Enterobacteriaceae in vegetable wastes showed correlation with carbon disulfide and dimethyl sulfide, while dominant Peptococcus, Bacteroides, Lactobacillales and Peptoniphilus in meat wastes was related to dimethyl disulfide. Overall, significant differences and correlation between VOCs emission profiles and bacterial communities among different food wastes decomposition were observed. These data contribute to a more comprehensive understanding the relationship between microbial community dynamics and malodorous VOCs emission.

Towards a risk evaluation of workers' exposure to handborne and airborne microbial species as exemplified with waste collection workers

Bioaerosol exposure is associated with health problems. The aim of this study is to evaluate whether it is possible to assess the risks posed by waste collection workers' exposure through identification and characterization of bacterial and fungal species, to which the workers are exposed. Using MALDI-TOF MS, microorganisms in waste collection workers' exposure through air, hand, and contact with the steering wheel were identified. Fungi found in high concentrations from the workers' exposure were characterized for the total inflammatory potential (TIP), cytotoxicity, and biofilm-forming capacity. In total, 180 different bacterial and 37 different fungal species in the workers' exposure samples were identified. Some of them belong to Risk Group 2, e.g. Escherichia coli, Klebsiella oxytoca, Staphylococcus aureus, and Aspergillus fumigatus, some have been associated with occupational health problems e.g. Penicillium citrinum and P. glabrum and some are described as emerging pathogens e.g. Aureobasidium pullulans. The TIP of fungal species was dose-dependent. High TIP values were found for Penicillium italicum, P. brevicompactum, P. citrinum, and P. glabrum. Several species were cytotoxic, e.g. A. niger and P. expansum, while some, e.g. P. chrysogenum, did not affect the cell viability. Based on waste workers' average inhalation rate, they inhaled up to 2.3 × 10⁴ cfu of A. niger, 7.4 × 10⁴ cfu of P. expansum, and 4.0 × 10⁶ cfu of P. italicum per work day. Some species e.g. A. niger and P. citrinum were able to form biofilm. In conclusion, the workers were exposed to several species of microorganisms of which some to varying degrees can be evaluated concerning risk. Thus, some microorganisms belong to Risk Group 2, and some are described as causing agents of occupational health problems, emerging pathogens, or intrinsically antibiotic resistant. For some other species very little is known. The TIP, cytotoxicity, and ability to form biofilm of the dominating fungi support and expand previous findings. These parameters depended on the species and the dose, thus highlighting the importance of species identification and exposure level in the risk assessment of exposure.

Variations and environmental impacts of odor emissions along the waste stream

Odor nuisance related to municipal solid waste (MSW) disposal is one of the main incentives to counter the Not-In-My-Backyard Syndrome. Moreover, integrated odor management contributes to specific odor control at different waste treatment stages. In this study, odor emissions along typical MSW streams were categorized based on their olfactive and environmental impacts after a field investigation of the residential district (RD), transfer station (TS), and landfill (LF) in the Chongming Eco-island. It was found that odorants, especially NH₃ and sulfides, increased along the MSW stream, with total chemical concentration increasing from 1241.5 ± 235.6 to 6947.2 ± 1726.8 μg/m³. Source separation and co-landfill system, which premixes the MSW with bottom ash (BA) at a ratio of 5:1, were speculated to efficiently attenuate odorants. Sulfides reduced owing to an increase in trace metal dissolution and carbon source consumption with the addition of BA at the LF, whereas NH₃ in the leachate pond increased due to enhanced biodegradation and alkalinity. Photochemical ozone formation (6.7 × 10^-8-8.6 × 10^-5 personal equivalent, PE), nutrient enrichment (5.4 × 10^-8-4.6 × 10^-5 PE), and acidification (4.8 × 10^-8-4.1 × 10^-5 PE) were the major environmental impact categories. The priority odor pollutants screened using ternary fuzzy synthetic system could reflect the impact of olfaction and environment and greatly varied along the waste stream.

Microbiological Air Quality and Drug Resistance in Airborne Bacteria Isolated from a Waste Sorting Plant Located in Poland-A Case Study

International interests in biological air pollutants have increased rapidly to broaden the pool of knowledge on their identification and health impacts (e.g., infectious, respiratory diseases and allergies). Antibiotic resistance and its wider implications present us with a growing healthcare crisis, and an increased understanding of antibiotic-resistant bacteria populations should enable better interpretation of bioaerosol exposure found in the air. Waste sorting plant (WSP) activities are a source of occupational bacterial exposures that are associated with many health disorders. The objectives of this study were (a) to assess bacterial air quality (BAQ) in two cabins of a WSP: preliminary manual sorting cabin (PSP) and purification manual sorting cabin (quality control) (QCSP), (b) determine the particle size distribution (PSD) of bacterial aerosol (BA) in PSP, QCSP, and in the outdoor air (OUT), and (c) determine the antibiotic resistance of isolated strains of bacteria. Bacterial strains were identified on a Biolog GEN III (Biolog, Hayward, CA, USA), and disc diffusion method for antimicrobial susceptibility testing was carried out according to the Kirby-Bauer Disk Diffusion Susceptibility Test Protocol. A large share of fecal bacteria, Enterococcus faecalis and Alcaligenes faecalis spp. feacalis, was found in the tested indoor air, which is a potential health hazard to the workers of the monitored WSP. Our results demonstrate the necessity to take into account fecal air pollution levels to avoid making erroneous assumptions regarding the environmental selection of antibiotic resistance. Total elimination of many anthropogenic sources is not possible, but important findings of this study can be used to develop realistic management policies methods to improve BAQ.

The Dose of Fungal Aerosol Inhaled by Workers in a Waste-Sorting Plant in Poland: A Case Study

Bioaerosol monitoring is a rapidly emerging area in the context of work environments because microbial pollution is a key element of indoor air pollution and plays an important role in certain infectious diseases and allergies. However, as yet, relatively little is known about inhaled doses of microorganisms in workplaces. Today, the important issue of social concern is due to waste management, transport, sorting, and processing of wastes and their environmental impact and effects on public health. In fact, waste management activities can have numerous adverse effects on human wellbeing. Health effects are generally linked to exposure (EX), defined as the concentration of a contaminant and the length of time a person is exposed to this concentration. Dose is an effective tool for evaluating the quantity of a contaminant that actually crosses the body’s boundaries and influences the goal tissue. This document presents an analysis of the fungal waste-sorting plant EX dose (FWSPED) inhaled by workers in a waste-sorting plant (WSP) in Poland in March 2019. The main purpose of this research was to assess FWSPED inhaled by workers in two cabins at the WSP: the preliminary manual sorting cabin (PSP) and the purification manual sorting cabin (quality control; QSP). It was found that the FWSPED inhaled by workers was 193 CFU/kg in the PSP and 185 CFU/kg in the QSP. Fungal particles were quantitatively evaluated and qualitatively identified by the GEN III Biolog system. During the research, it was found that isolates belonging to the Aspergilus flavus and Penicillum chrysogenum strains were detected most frequently in the WSP. The total elimination of many anthropogenic sources is not possible, but the important findings of this research can be used to develop realistic management policies and methods to improve the biological air quality of WSPs for effective protection of WSP workers.

Exposure to Bacterial and Fungal Aerosols: Microorganism Indices in A Waste-Sorting Plant in Poland

An increased understanding of airborne microorganism populations should enable a better interpretation of bioaerosol exposure found in a working environment. An assessment of the contamination levels of mesophilic bacterial aerosol (MBA) and fungal aerosol (FA) was carried out using two evaluation indices for microbiological pollution—the total index of microbiological contamination per cubic meter (TIMC/m³) and the indoor–outdoor index (IOI). An advantage of selected indices is the inclusion of several co-existing factors that have an impact on the formation of bioaerosol. When properly used, they also highlight the low efficiency of the ventilation system caused by an insufficient air exchange. In this study, the microbial air quality (MAQ) of the working environment was assessed during the spring season at a sorting plant located in Southern Poland. Sampling was undertaken in the plant using an Andersen six-stage impactor which allows the obtainment of information about the size distribution of the air microflora. The value of average concentrations of MBA and the average concentration of FA collected in the preliminary cabin of the sorting plant (PCSP) and the cleaning cabin of the sorting plant (CCSP) were analyzed. The obtained values of MBA were 1.6 times higher indoors, compared to outdoors, while FA was 1.7 times higher outdoors than indoors. The maximum TIMC/m³ value was obtained in PCSP (2626). The calculated IOI in this study suggests that MBA concentrations are influenced by internal sources, as opposed to FA. The purpose of this work was to present the usefulness of using indices in assessing air quality.

Air Quality and Potential Health Risk Impacts of Exposure to Bacterial Aerosol in a Waste Sorting Plant Located in the Mountain Region of Southern Poland, Around Which There Are Numerous Rural Areas

Many studies have shown an association between working in waste sorting plants (SP) and occupational health problems, such as skin irritation or pulmonary diseases. These symptoms have been related to biological aerosol exposure. The main goal of this work was to assess the levels of concentration and the characteristics of bacterial aerosols in waste sorting plants, based on measurements taken in a plant located in the mountain region of Southern Poland, around which there are numerous rural areas. The average concentrations of culturable bacterial aerosol (CCBA) collected in the unloading hall of the waste sorting plant (UHSP) and the outdoor air of the sorting plant (OSP) were 2687 CFU/m3 and 1138 CFU/m3, respectively. Sampling was undertaken in the plant using an Andersen six-stage impactor (with aerodynamic cut-off diameters of 7.0, 4.7, 3.3, 2.1, 1.1, and 0.65 μm), during the spring of 2019. Size distributions were unimodal, with a peak in particle bacterial aerodynamic diameters at less than 3.3 µm, increasing the potentially adverse health effects of their inhalation. An analysis was conducted to determine the antibiotic resistance of isolated strains of bacteria. During the study, it was found that isolates belonging to the genus Bacillus were most frequently detected in the waste sorting plant. Isolates with the highest resistance to antibiotics belonged to the genus Neisseria. This test indicates that the use of personal protective equipment is necessary.

Expanded cardboard waste sorting and occupational exposure to microbial species

Member states of the European Union have to maximize recycling. The current, Danish cardboard recycling system can be improved by increasing the kinds of cardboard products that can be recycled to include e.g. used beverage cartons and pizza boxes (i.e. an expanded cardboard fraction (ECF)). This study aims to obtain knowledge about exposure to airborne endotoxin and microorganisms at species level at different collection frequencies of ECF, and whether an increase in waste sorted fractions means that each waste fraction is collected less frequently. Bacterial and endotoxin concentrations were associated significantly with temperature inside the waste containers and endotoxin and fungal exposures with collection frequency. The concentration of fungi was highest at the truck back and for reduced collection frequencies. The geometric mean diameters of particles with bacteria were between 3.0 and 5.2 μm and with fungi between 3.8 μm and 6.0 μm. In total, 81 and 25 different bacterial and fungal species were found at the waste receiving plant, respectively. Work with ECF caused exposures to food-related microorganisms (e.g. Arthrobacter arilaitensis and Penicillium camemberti), potential pathogens (e.g. Bacillus cereus, Salmonella sp. and P. expansum), and commensal bacteria. Bacillus cereus and Salmonella were found in the particle size fraction often being swallowed. Workers collecting EFC will be at risk of being exposed to microbial species that normally are related to residual waste. It seems to be advisable with an EFC collection frequency shorter than eight weeks. However, introduction of new waste fractions has generally been associated with reduced collection frequencies.

A review on recent progress in observations, and health effects of bioaerosols

Bioaerosol is a particulate mixture of solid and semi-solid matter combined with biotic matter like pollens, microbes and their fragments. The present review stresses on a cumulative understanding of sources, components, quantification and distribution of bioaerosols with respect to size, and its significant impacts on human health. The present review will be instrumental in devising strategies to understand and manage bioaerosols and reducing their human exposure and associated health hazards. The present review aims explore the relationship between particle and associated biological agents responsible for behaviours like dispersal, total potential health hazards and toxicology level during exposure to bioaerosol.

Airborne bioaerosols and their impact on human health

Bioaerosols consist of aerosols originated biologically such as metabolites, toxins, or fragments of microorganisms that are present ubiquitously in the environment. International interests in bioaerosols have increased rapidly to broaden the pool of knowledge on their identification, quantification, distribution, and health impacts (e.g., infectious and respiratory diseases, allergies, and cancer). However, risk assessment of bioaerosols based on conventional culture methods has been hampered further by several factors such as: (1) the complexity of microorganisms or derivatives to be investigated; (2) the purpose, techniques, and locations of sampling; and (3) the lack of valid quantitative criteria (e.g., exposure standards and dose/effect relationships). Although exposure to some microbes is considered to be beneficial for health, more research is needed to properly assess their potential health hazards including inter-individual susceptibility, interactions with non-biological agents, and many proven/unproven health effects (e.g., atopy and atopic diseases).

The Use of Bioaerosol Sampling for Airborne Virus Surveillance in Swine Production Facilities: A Mini Review

Modern swine production facilities typically house dense populations of pigs and may harbor a variety of potentially zoonotic viruses that can pass from one pig generation to another and periodically infect human caretakers. Bioaerosol sampling is a common technique that has been used to conduct microbial risk assessments in swine production, and other similar settings, for a number of years. However, much of this work seems to have been focused on the detection of non-viral microbial agents (i.e., bacteria, fungi, endotoxins, etc.), and efforts to detect viral aerosols in pig farms seem sparse. Data generated by such studies would be particularly useful for assessments of virus transmission and ecology. Here, we summarize the results of a literature review conducted to identify published articles related to bioaerosol generation and detection within swine production facilities, with a focus on airborne viruses. We identified 73 scientific reports, published between 1991 and 2017, which were included in this review. Of these, 19 (26.7%) used sampling methodology for the detection of viruses. Our findings show that bioaerosol sampling methodologies in swine production settings have predominately focused on the detection of bacteria and fungi, with no apparent standardization between different approaches. Information, specifically regarding virus aerosol burden in swine production settings, appears to be limited. However, the number of viral aerosol studies has markedly increased in the past 5 years. With the advent of new sampling technologies and improved diagnostics, viral bioaerosol sampling could be a promising way to conduct non-invasive viral surveillance among swine farms.

Volatile compounds emission and health risk assessment during composting of organic fraction of municipal solid waste

Degradation of mechanically sorted organic fraction (MSOF) of municipal solid waste in composting facilities is among the major contributors of volatile compounds (VCs) generation and emission, causes nuisance problems and health risks on site as well as in the vicinages. The aim of current study was to determine the seasonal (summer and winter) variation and human health risk assessment of VCs in the ambient air of different processing units in MSOF at composting plant in China. Average concentration of VCs was 58.50 and 138.03mg/m³ in summer and winter respectively. Oxygenated compounds were found to be the highest concentration (46.78-91.89mg/m³) with ethyl alcohol as the major specie (43.90-85.31mg/m³) in the two seasons respectively. Nevertheless, individual non-carcinogenic (Hazard relation i.e HR<1) and carcinogenic risk (CR<1.0E-04) of the quantified VCs were within acceptable limit except naphthalene at biofilter unit. In addition, cumulative non-carcinogenic risk exceeded from the threshold limit both in summers and winters in all units except at biofilter unit during winter. Furthermore cumulative carcinogenic risk also exceeded at same unit during the summer season. Therefore special attention should be made to minimize cumulative non-carcinogenic and carcinogenic risk as people are well exposed to mixture of compounds, not to individual.

Waste Workers’ Exposure to Airborne Fungal and Bacterial Species in the Truck Cab and During Waste Collection

A large number of people work with garbage collection, and exposure to microorganisms is considered an occupational health problem. However, knowledge on microbial exposure at species level is limited. The aim of the study was to achieve knowledge on waste collectors’ exposure to airborne inhalable fungal and bacterial species during waste collection with focus on the transport of airborne microorganisms into the truck cab. Airborne microorganisms were collected with samplers mounted in the truck cab, on the workers’ clothes, and outdoors. Fungal and bacterial species were quantified and identified. The study showed that the workers were exposed to between 112 and 4.8×10⁴ bacteria m⁻³ air and 326 and 4.6×10⁴ fungi m⁻³ air. The personal exposures to bacteria and fungi were significantly higher than the concentrations measured in the truck cabs and in the outdoor references. On average, the fungal and bacterial concentrations in truck cabs were 111 and 7.7 times higher than outdoor reference measurements. In total, 23 fungal and 38 bacterial species were found and identified. Most fungal species belonged to the genus Penicillium and in total 11 Penicillium species were found. Identical fungal species were often found both in a personal sample and in the same person’s truck cab, but concentrations were on average 27 times higher in personal samples. Concentrations of fungal and bacterial species found only in the personal samples were lower than concentrations of species also found in truck cabs. Skin-related bacteria constituted a large fraction of bacterial isolates found in personal and truck cab samples. In total, six Staphylococcus species were found. In outdoor samples, no skin-related bacteria were found. On average, concentrations of bacterial species found both in the truck cab and personal samples were 77 times higher in personal samples than in truck cab samples. In conclusion, high concentrations of fungi were found in truck cabs, but the highest concentrations were found in personal samples; fungal and bacterial species found in high concentrations in personal samples were also found in truck cabs, but in lower concentrations indicating that both fungi and bacteria are transported by the workers into the truck cab, and are subsequently aerosolized in the truck cab.

Emission of oxygenated volatile organic compounds (OVOCs) during the aerobic decomposition of orange wastes

Oxygenated volatile organic compounds (OVOCs) emitted from orange wastes during aerobic decomposition were investigated in a laboratory-controlled incubator for a period of two months. Emission of total OVOCs (TOVOCs) from orange wastes reached 1714 mg/dry kg (330 mg/wet kg). Ethanol, methanol, ethyl acetate, methyl acetate, 2-butanone and acetaldehyde were the most abundant OVOC species with shares of 26.9%, 24.8%, 20.3%, 13.9%, 2.8% and 2.5%, respectively, in the TOVOCs released. The emission fluxes of the above top five OVOCs were quite trivial in the beginning but increased sharply to form one "peak emission window" with maximums at days 1-8 until leveling off after 10 days. This type of "peak emission window" was synchronized with the CO2 fluxes and incubation temperature of the orange wastes, indicating that released OVOCs were mainly derived from secondary metabolites of orange substrates through biotic processes rather than abiotic processes or primary volatilization of the inherent pool in oranges. Acetaldehyde instead had emission fluxes decreasing sharply from its initial maximum to nearly zero in about four days, suggesting that it was inherent rather than secondarily formed. For TOVOCs or all OVOC species except 2-butanone and acetone, over 80% of their emissions occurred during the first week, implying that organic wastes might give off a considerable amount of OVOCs during the early disposal period under aerobic conditions.

Effect of temperature on bacterial emissions in composting of swine manure

Swine manure was subjected to laboratory scale composting in order to quantify bioaerosols, i.e., airborne culturable bacteria and endotoxin, in the exhaust gas, which provided details on the effect of temperature on bacterial emissions. The concentration of airborne bacteria reached 31,250 colony-forming units (CFU)/m(3) during the thermophilic stage of composting, and positively correlated with the temperature profile of the compost pile. Initially, the endotoxin concentration was 1820 endotoxin units (EU)/m(3), but it decreased exponentially as the composting process proceeded. The temperature can be an excellent indicator of bacterial emissions during the composting process, indicating that the composting process requires a consistently high temperature to ensure sanitization of both compost and bacterial emissions. The cumulative emission data showed that emission factors was 11.2-13.5 CFU/g dry swine manure and that of endotoxin was 0.5-0.9 EU/g dry swine manure. The bacterial diversity in the bioaerosol was analyzed by polymerase chain reaction-denaturing gradient gel electrophoresis, revealing the presence of various gram-negative bacterial consortia.