Household solid waste combustion with wood increases particulate trace metal and lung deposited surface area emissions

Contrasting features of winter-time PM2.5 pollution and PM2.5-toxicity based on oxidative potential: A long-term (2016-2023) study over Kolkata megacity at eastern Indo-Gangetic Plain

The present study is an attempt to understand the level of PM2.5 pollution and its toxicity based on the oxidative potential (OP) during the winter-time pollution period over Kolkata, a megacity at the eastern most parts of Indo-Gangetic Plain (IGP) during the period of 2016-2023. We have assessed the effectiveness of the Government of India's national mission, the National Clean Air Program (NCAP) in PM2.5 reduction over this city, and the study revealed that the mission has been efficacious in lessening the PM2.5 load by 28 % from pre-NCAP (2016-2019) to post-NCAP (2021-2023) periods. Several policy interventions reduced the contributions from various anthropogenic sources; however, biomass/solid waste burning remained a major concern with no significant reduction. The results revealed that the volume-weighted OP (OPv) remains mass-independent and the same when PM2.5 remains within 70 μg m-3 (OPv range between 2.7 and 3.1 nmol DTT min-1 m-3). With the rise in PM2.5 mass from 70 μg m-3, OPv boosts up sharply and reaches its peak (at ∼145 μg m-3 during pre-NCAP and ∼105 μg m-3 during post-NCAP) followed by an insignificant change with the further rise in PM2.5. We observed that biomass/solid waste burning is the major concern over Kolkata in the current scenario (post-NCAP) even after NCAP policy interventions. Such high OP-based toxicity of PM2.5 during post-NCAP periods could be minimized if actions are taken against this particular source.

Evaluating emissions and air quality implications of residential waste incineration

In Europe mainly at winter season the PM levels exceed air quality limits, which correlated with the operation of solid-fired boilers. More and more people are returning to using these devices due to energy shortage caused by the pandemic and regional conflicts. In addition, the phenomena of co-burning fuels and municipal waste in residential boilers in primarily fuel poverty households increases further the amount of pollutants in the atmosphere. This study aims to correlate the quantity and quality of air pollutants with the type of fuel (wood and wastes) burned. Combustion experiments were conducted using oak fuel mixed with three waste groups: (1) plastics (PP, HDPE, PET); (2) textiles (polyester-PES, cotton-COT); and (3) papers (cardboard-CARD, glossy coated paper-GCP, 84C/PAP). The addition of waste to wood fuel altered the morphology of emitted particles. While waste burning doesn't always increase particle quantity, it significantly raises PAH concentrations. A strong relationship exists between waste type, particle morphology, and PAH quality, where with lower molecular weight PAHs linked to tar agglomerates and higher ones to soot agglomerates with inorganic crystals.

Refined Sea Salt Markers for Coastal Cities Facilitating Quantification of Aerosol Aging and PM2.5 Apportionment

Sea salt (ss) aerosols in PM2.5 are often quantified through source apportionment by applying sodium (Na+) and chloride (Cl-) as the markers, but both markers can be substantially emitted from anthropogenic sources. In this study, we differentiate ss from nonss (nss) portions of Na+ and Cl- to better apportion PM2.5 in a coastal tropical urban environment. Size-resolved ionic profiles accounting for Cl- depletion of aged ss were applied to 162-day measurements during 2012 and 2018-2019. Results show that the nss (likely anthropogenic) portions, on average, account for 50-80% of total Na+ and Cl- in submicron aerosols (PM1). This corresponds to up to 2.5 μg/m3 of ss in submicron aerosols that can be ∼10 times overestimated if one attributes all Na+ and Cl- in PM1 to ss. Employing the newly speciated ss- and nss-portions of Na+ and Cl- to source apportionment of urban PM2.5 via positive matrix factorization uncovers a new source of transported anthropogenic emissions during the southwest monsoon, contributing to 12-15% of PM2.5. This increases anthropogenic PM2.5 by ≥19% and reduces ss-related PM2.5 by >30%. In addition to demonstrating Cl- depletion (aging) in submicron aerosols and quantifying ssNa+, nssNa+, ssCl-, as well as nssCl- therein, the refined PM2.5 apportionment resolves new insights on PM2.5 of anthropogenic origins in urban environments, useful to facilitate policy making.

Acidity and oxidative potential of atmospheric aerosols over a remote mangrove ecosystem during the advection of anthropogenic plumes

To investigate the acidity and the water-soluble oxidative potential of PM10, during the continental biomass-burning plume transport, a three-year (2018-2020) winter-time campaign was conducted over a pristine island (21.35°N, 88.32°E) of Sundarban mangrove ecosystem situated at the shore of Bay of Bengal. The average PM10 concentration over Sundarban was found to be 98.3 ± 22.2 μg m-3 for the entire study period with a high fraction of non-sea-salt- SO42- and water-soluble organic carbons (WSOC) that originated from the regional solid fuel burning. The thermodynamic E-AIM(IV) model had estimated that the winter-time aerosols over Sundarban were acidic (pH:2.4 ± 0.6) and mainly governed by non-sea-salt-SO42-. The volume and mass normalized oxidative potential of PM10 was found to be 1.81 ± 0.40 nmol DTT min-1 m-3 and 18.4 ± 6.1 pmol DTT min-1 μg-1 respectively which are surprisingly higher than several urban atmospheres across the world including IGP. The acid-digested water-soluble transition metals (Cu, Mn) show higher influences in the oxidative potential (under high aerosol acidity) compared to the WSOC. The study revealed that the advection of regional solid fuel burning plume and associated non-sea-salt-SO42- is enhancing aerosol acidity and oxidative stress that in turn alters the intrinsic properties of aerosols over such marine ecosystems rich in ecology and bio-geochemistry.

Characterizing metals in particulate pollution in communities at the fenceline of heavy industry: combining mobile monitoring and size-resolved filter measurements

Exposures to metals from industrial emissions can pose important health risks. The Chester-Trainer-Marcus Hook area of southeastern Pennsylvania is home to multiple petrochemical plants, a refinery, and a waste incinerator, most abutting socio-economically disadvantaged residential communities. Existing information on fenceline community exposures is based on monitoring data with low temporal and spatial resolution and EPA models that incorporate industry self-reporting. During a 3 week sampling campaign in September 2021, size-resolved particulate matter (PM) metals concentrations were obtained at a fixed site in Chester and on-line mobile aerosol measurements were conducted around Chester-Trainer-Marcus Hook. Fixed-site arsenic, lead, antimony, cobalt, and manganese concentrations in total PM were higher (p < 0.001) than EPA model estimates, and arsenic, lead, and cadmium were predominantly observed in fine PM (<2.5 μm), the PM fraction which can penetrate deeply into the lungs. Hazard index analysis suggests adverse effects are not expected from exposures at the observed levels; however, additional chemical exposures, PM size fraction, and non-chemical stressors should be considered in future studies for accurate assessment of risk. Fixed-site MOUDI and nearby mobile aerosol measurements were moderately correlated (r ≥ 0.5) for aluminum, potassium and selenium. Source apportionment analyses suggested the presence of four major emissions sources (sea salt, mineral dust, general combustion, and non-exhaust vehicle emissions) in the study area. Elevated levels of combustion-related elements of health concern (e.g., arsenic, cadmium, antimony, and vanadium) were observed near the waste incinerator and other industrial facilities by mobile monitoring, as well as in residential-zoned areas in Chester. These results suggest potential co-exposures to harmful atmospheric metal/metalloids in communities surrounding the Chester-Trainer-Marcus Hook industrial area at levels that may exceed previous estimates from EPA modeling.

Snapshots of wintertime urban aerosol characteristics: Local sources emphasized in ultrafine particle number and lung deposited surface area

Urban air fine particles are a major health-relating problem. However, it is not well understood how the health-relevant features of fine particles should be monitored. Limitations of PM_2.5 (mass concentration of sub 2.5 μm particles), which is commonly used in the health effect estimations, have been recognized and, e.g., World Health Organization (WHO) has released good practice statements for particle number (PN) and black carbon (BC) concentrations (2021). In this study, a characterization of urban wintertime aerosol was done in three environments: a detached housing area with residential wood combustion, traffic-influenced streets in a city centre and near an airport. The particle characteristics varied significantly between the locations, resulting different average particle sizes causing lung deposited surface area (LDSA). Near the airport, departing planes had a major contribution on PN, and most particles were smaller than 10 nm, similarly as in the city centre. The high hourly mean PN (>20 000 1/cm³) stated in the WHO's good practices was clearly exceeded near the airport and in the city centre, even though traffic rates were reduced due to a SARS-CoV-2-related partial lockdown. In the residential area, wood combustion increased both BC and PM_2.5, but also PN of sub 10 and 23 nm particles. The high concentrations of sub 10 nm particles in all the locations show the importance of the chosen lower size limit of PN measurement, e.g., WHO states that the lower limit should be 10 nm or smaller. Furthermore, due to ultrafine particle emissions, LDSA per unit PM_2.5 was 1.4 and 2.4 times higher near the airport than in the city centre and the residential area, respectively, indicating that health effects of PM_2.5 depend on urban environment as well as conditions, and emphasizing the importance of PN monitoring in terms of health effects related to local pollution sources.

The impact of brick kilns on environment and society: a bibliometric and thematic review

Bricks have a long history of being utilized as a construction material across the globe. The production processes involved in the manufacture of bricks have a significant impact on the environment, human health, economy, and society. This study conducts a thematic and bibliometric analysis to provide an in-depth review of the effects of brick kilns on humans and the environment. The PRISMA framework was used to identify relevant articles from the Web of Science database, resulting in the selection and critical review of 348 articles. The bibliometric analysis included an evaluation of historical growth, keywords, citation and co-citation, organizations, and countries. The articles were published in 213 journals, written by 1396 authors from 670 institutions in 66 countries. Thematic analysis revealed that brick kilns have a negative impact on the environment, including soil damage, and cause health problems for kiln workers and animals. Modern slavery and societal issues also persist in developing countries. The current research is focused on finding alternative materials for brick manufacturing, improving industry energy efficiency, managing waste, and technological advancements, such as the implementation of the zigzag or Hoffmann kiln to reduce pollution. In developing countries, utilizing waste from other industries in brick production can effectively lower production costs. While developed countries have embraced advanced technologies for brick production, it is recommended that developing countries adopt awareness campaigns to encourage the upgrading of kilns to cleaner and more sustainable systems. Future research directions should aim to support brick kiln owners in adopting such systems.

Evaluation of flue gas emission factor and toxicity of the PM-bounded PAH from lab-scale waste combustion

Atmospheric particulate matter (PM) has a significant threat not only to human health but also to our environment. In Hungary, 54% of PM10 comes from residential combustion, which also includes the practice of household waste burning. Therefore, this work aims to investigate the quality of combustion through the flue gas concentrations (CO, CO₂, O₂) and to identify and evaluate the negative impacts of PM and PAHs generated during controlled lab-scale combustion of different mixed wastes (cardboard and glossy paper, polypropylene and polyethylene terephthalate, polyester and cotton). Mixed wastes were burnt in a lab-scale tubular furnace at different temperatures with 180 dm³/h air flow rate. Chemical analyses were coupled with ecotoxicological tests using the bioluminescent bacterium Vibrio fischeri. Ecotoxicity was expressed as toxic unit (TU) values, toxic equivalent factors (TEF) were also presented. During the combustion same amount of O₂ enters the reaction, but a different amount CO₂ is generated due to the C content of the sample. The waste with highest C-content related to the highest CO₂ emission. Increasing the combustion temperature produces more PM-bound PAHs, which remains the same composition in the case of plastic and textile groups. The TU of solid contaminants decreases with increasing combustion temperature and increases with the minerals which are left behind in the water from the solid contaminants.

Investigation of gaseous and solid pollutants emitted from waste tire combustion at different temperatures

Consumer society requires the continuous evolution of products, thus generating a lot of waste. The automotive industry has also undergone significant development, generating 1.5 billion used tires worldwide every year. Landfilling of tires is prohibited and their disposal is therefore a major issue. Although many studies deal with the utilization of tire as a fuel, there is limited research that would specifically describe the relationship between pollutant emissions from tire combustion and the relationship between emitted pollutants and firebox temperature. Based on this, this work aims to investigate flue gas concentrations (CO, CO₂, NO_x, and SO₂) and solid pollutants from tire burned in a lab-scale electrical furnace at firebox temperature from 650 to 900 °C. The decomposition of the CaCO₃ filler during the combustion of the tire has been detected with thermal analytical investigation and combustion experiments. In the case of the CO flue gas pollutant, a second maximum concentration is observed due to the presence of CaCO_3. With the increasing firebox temperature, the size of solid particles decreases, and the mesh structure formed becomes denser. At the same time, the concentration of emitted solid PAHs decreases, dominated by aromatic compounds with smaller number of rings. However, the variation of firebox temperature does not affect the amount of benzo(b)fluoranthene and fluoranthene relative to the total concentration.

Ecotoxic emissions generated by illegal burning of household waste

The practice of burning household waste including different types of plastic is illegal in Hungary, still an existing problem. As environmental consequences are hardly known, this study attempts to give an initial estimation of the ecotoxicity generated during controlled combustion of different waste types. These samples included polystyrene (PS), polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polyurethane (PU), oriented strand board (OSB) and rag (RAG). Ecotoxicological profiling was completed using the following test battery: Vibrio fischeri bioluminescence inhibition assay, Daphnia magna immobility test and the seedling emergence assay. Also, genotoxicity of plastic waste samples was assessed using the SOS Chromotest. Concerning main pollutants in the samples, the samples could be distinguished as 'PAH-type' and 'heavy metal-type' samples. PVC, PU and PS samples showed the highest toxicity in the Vibrio and Daphnia assays. The PVC sample was characterized by an extremely high cadmium concentration (22.4 μg/L), PS, PP and PU samples on the contrary had high total PAH content. While Vibrio and Daphnia showed comparable sensitivity, the phytotoxicity assay had no response for any of the samples tested. Samples originating from the controlled burning of different plastic types such as PU, PVC, PS and PP were classified as genotoxic, PS sample showed extremely high genotoxicity. Genotoxicity expressed as SOSIF showed strong correlation with most of the PAHs detected.