Influence of fireworks displays on the chemical characteristics of PM2.5 in rural and suburban areas in Central and East China

New insights into the influences of firework combustion on molecular composition and formation of sulfur- and halogen-containing organic compounds

Firework (FW) events occur during various festivals worldwide and substantially negatively influence both air quality and human health. However, the effects of FWs on the chemical properties and formation of organic aerosols are far from clear. In this study, fine particulate matter (PM2.5) samples were collected in a suburban area in Qingdao, China during the Chinese Spring Festival. The concentrations of chemical species (especially carbonaceous components) in PM2.5 were measured using a combination of several state-of-the-art techniques. Our results showed that mass concentrations of water-soluble sulfate, potassium and chloride ions, and organic carbon drastically increased and became the predominant components in PM2.5 during FW events. Correspondingly, both the number and fractional contributions of sulfur (S)-containing subgroups (e.g., CHOS and CHONS compounds) and some chlorine (Cl)-containing organic (e.g., CHOSCl and CHONSCl) compounds identified using ultrahigh-resolution Fourier-transform ion cyclotron resonance mass spectrometry (FT-ICR MS) increased. The S- and Cl-containing compounds unique to the FW display period were identified, and their chemical characterization, sources, and formation mechanisms were elucidated by combining FT-ICR MS and quantum chemical calculations. Our results suggest that FW emissions play notable roles in both primary and secondary organic aerosol formation, especially for CHOS- and Cl-containing organic compounds.

Relaxation of Spring Festival Firework Regulations Leads to a Deterioration in Air Quality

The relaxation of restrictions on Chinese Spring Festival (SF) firework displays in certain regions has raised concerns due to intensive emissions exacerbating air quality deterioration. To evaluate the impacts of fireworks on air quality, a comparative investigation was conducted in a city between 2022 (restricted fireworks) and 2023 SF (unrestricted), utilizing high time-resolution field observations of particle chemical components and air quality model simulations. We observed two severe PM2.5 pollution episodes primarily triggered by firework emissions and exacerbated by static meteorology (contributing approximately 30%) during 2023 SF, contrasting with its absence in 2022. During firework displays, freshly emitted particles containing more primary inorganics (such as chloride and metals like Al, Mg, and Ba), elemental carbon, and organic compounds (including polycyclic aromatic hydrocarbons) were predominant; subsequently, aged particles with more secondary components became prevalent and continued to worsen air quality. The primary emissions from fireworks constituted 54% of the observed high PM2.5 during the displays, contributing a peak hourly PM2.5 concentration of 188 μg/m3 and representing over 70% of the ambient PM2.5. This study underscores that caution should be exercised when igniting substantial fireworks under stable meteorological conditions, considering both the primary and potential secondary effects.

Light absorption enhancement of black carbon and its impact factors during winter in a megacity of the Sichuan Basin, China

Carbonaceous aerosols play a vital role in global climate patterns due to their potent light absorption capabilities. However, the light absorption enhancement effect (Eabs) of black carbon (BC) is still subject to great uncertainties due to factors such as the mixing state, coating material, and particle size distribution. In this study, fine particulate matter (PM2.5) samples were collected in Chengdu, a megacity in the Sichuan Basin, during the winter of 2020 and 2021. The chemical components of PM2.5 and the light absorption properties of BC were investigated. The results revealed that secondary inorganic aerosols and carbonaceous aerosols were the dominant components in PM2.5. Additionally, the aerosol filter filtration-dissolution (AFD) treatment could improve the accuracy of measuring elemental carbon (EC) through thermal/optical analysis. During winter in Chengdu, the absorption enhancement values of BC ranged between 1.56 and 2.27, depending on the absorption wavelength and the mixing state of BC and non-BC materials. The presence of internally mixed BC and non-BC materials significantly contributed to Eabs, accounting for an average of 68 % at 405 nm and 100 % at 635 nm. The thickness of the BC coating influenced Eabs, displaying an increasing-then-decreasing trend. This trend was primarily attributed to the hygroscopic growth and dehydration shrinkage of particulate matter. Nitrate, as the major component of BC coating, played a crucial role in the lensing effect and exhibited fast growth during variation in Eabs. By combining the results from PMF, we identified the secondary formation and vehicle emission as the primary contributors to Eabs. Consequently, this study can provide valuable insights into the optical parameters, which are essential for assessing the environmental quality, improving regional atmospheric conditions, and formulating effective air pollution control strategies.

Influence of pollution control measures on the reduction of black carbon in an urban site of megacity, Tianjin, China based on ground-monitored and MERRA-2 reanalysis data

The concentration of particulate matter (PM) has been reduced significantly with the implementation of air pollution control plans in Tianjin. However, as an important component of PM that can lead to global warming and adverse health effects, the influence of pollution control measures (PCM) on black carbon (BC) has been less studied. In this study, ten years of BC concentration satellite-based reanalysis data were collected from MERRA-2 (Modern-Era Retrospective Analysis for Research and Applications, Version 2), and their reliability was verified using ground-monitored BC data. Using the proposed Kolmogorov-Zurbenko and artificial neural network (KZ-ANN) model, the influences of meteorology and emission measures were separated. The results indicated that the overall meteorological conditions were not conducive to BC diffusion, especially in autumn and winter with low temperature, surface solar radiation, boundary layer height, and high atmospheric pressure, all of which increased the BC concentration. This study also found that although a significant reduction in BC emissions was observed in Tianjin (the total emissions of BC in 2020 dropped by 52 % compared with the level in 2013), the change in emission-influenced BC was relatively low (the concentration of emission-influenced BC in 2022 dropped by only 2.39 % compared to that in 2013). The reduction of emission-influenced BC concentration during the air pollution prevention control and action plan (APPC) was higher than the level during of the three-year action plan for winning the blue sky defense war (abbreviated as the Blue Sky Defense War). In addition, the lockdown measures during the Corona Virus Disease 2019 (COVID-19) did not have beneficial effect on the reduction of emission-influenced BC concentration. This phenomenon can be explained by the long-range transport of BC from surrounding areas, which was also proven by the results of the backward trajectory analysis. Therefore, efforts on emissions reduction in Tianjin were diminished. It is necessary to cooperate with the governments in surrounding areas to implement joint BC control measures, especially in autumn and winter.

Source apportionment of PM2.5 using PMF combined online bulk and single-particle measurements: Contribution of fireworks and biomass burning

Fireworks (FW) could significantly worsen air quality in short term during celebrations. Due to similar tracers with biomass burning (BB), the fast and precise qualification of FW and BB is still challenging. In this study, online bulk and single-particle measurements were combined to investigate the contributions of FW and BB to the overall mass concentrations of PM2.5 and specific chemical species by positive matrix factorization (PMF) during the Chinese New Year in Hong Kong in February 2013. With combined information, fresh/aged FW (abundant 140K2NO3+ and 213K3SO4+ formed from 113K2Cl+ discharged by fresh FW) can be extracted from the fresh/aged BB sources, in addition to the Second Aerosol, Vehicles + Road Dust, and Sea Salt factors. The contributions of FW and BB were investigated during three high particle matter episodes influenced by the pollution transported from the Pearl River Delta region. The fresh BB/FW contributed 39.2% and 19.6% to PM2.5 during the Lunar Chinese New Year case. However, the contributions of aged FW/BB enhanced in the last two episodes due to the aging process, evidenced by high contributions from secondary aerosols. Generally, the fresh BB/FW showed more significant contributions to nitrate (35.1% and 15.0%, respectively) compared with sulfate (25.1% and 5.9%, respectively) and OC (14.8% and 11.1%, respectively) on average. In comparison, the aged FW contributed more to sulfate (13.4%). Overall, combining online bulk and single-particle measurement data can combine both instruments' advantages and provide a new perspective for applying source apportionment of aerosols using PMF.

Bioavailability and regional transport of PM2.5 during heavy haze episode in typical coal city site of Fenwei Plain, China

Despite the decrease in anthropogenic emissions, haze episodes were still frequent in the Fenwei Plain, which was identified as one of the three key areas for air pollution control. Herein, PM_2.5 samples were collected to investigate the influence of festival effect during the Chinese Spring Festival from February 2rd to 13th, 2019, in Linfen on the Fenwei Plain. The characteristics of element pollution, enrichment factor, source apportionment, regional transport of PM_2.5, and health risk assessment were discussed. Meanwhile, the simulated lung fluid method (SLF) was carried out to accurately assess the inhalation risks of heavy metals (HMs). Results indicated that the average concentration of PM_2.5 was 195.6 μg·m^-3 during the studying period. Road fugitive dust (15.6%), firework burning source (25.6%), industrial emission (30.5%), and coal combustion (28.3%) were identified by positive matrix factorization (PMF) modeling. Using the HYSPLIT trajectory model, air masses from the central Shaanxi, southern Hebei, and northern Henan were the dominant transport paths during the Spring Festival, which contributed 21.9 and 41.2% of total trajectories, respectively. The findings that high PSCF and CWT levels were found in central Shaanxi, southern Hebei, and northern Henan were confirmed. The SLF mean bioaccessibility (%) of the solubility of particulate metals was in order of Mn > Ni > Sb > Ba > Zn > Pb > Cr. However, the carcinogenic risk value of Cr was the highest, exceeding the maximum acceptable risk. The present study provided important information for further analyzing the air pollution cause of Fenwei Plain.

Prediction of atmospheric pollutants in urban environment based on coupled deep learning model and sensitivity analysis

Accurate and efficient predictions of pollutants in the atmosphere provide a reliable basis for the scientific management of atmospheric pollution. This study develops a model that combines an attention mechanism, convolutional neural network (CNN), and long short-term memory (LSTM) unit to predict the O₃ and PM_2.5 levels in the atmosphere, as well as an air quality index (AQI). The prediction results given by the proposed model are compared with those from CNN-LSTM and LSTM models as well as random forest and support vector regression models. The proposed model achieves a correlation coefficient between the predicted and observed values of more than 0.90, outperforming the other four models. The model errors are also consistently lower when using the proposed approach. Sobol-based sensitivity analysis is applied to identify the variables that make the greatest contribution to the model prediction results. Taking the COVID-19 outbreak as the time boundary, we find some homology in the interactions among the pollutants and meteorological factors in the atmosphere during different periods. Solar irradiance is the most important factor for O₃, CO is the most important factor for PM_2.5, and particulate matter has the most significant effect on AQI. The key influencing factors are the same over the whole phase and before the COVID-19 outbreak, indicating that the impact of COVID-19 restrictions on AQI gradually stabilized. Removing variables that contribute the least to the prediction results without affecting the model prediction performance improves the modeling efficiency and reduces the computational costs.

Impact of fireworks burning on air quality during the Spring Festival in 2021-2022 in Linyi, a central city in the North China Plain

The management of fireworks has been strengthened during the Spring Festival in 2022 compared with that in 2021 in Linyi, a central city in the North China Plain. Online measurements of the chemical components of PM_2.5 were conducted during the Spring Festival in 2021-2022 to assess the influence of fireworks burning (FB) on air quality. Remarkable achievements have been made in improving air quality during FB period (FBP) in 2021-2022 attributing to the stringent regional emission reduction measures, fireworks control, and favorable meteorological conditions with the concentrations of PM_2.5, water-soluble ions, and carbonaceous aerosols decreasing by 73.6%, 78.8%, and 73.5%, respectively. The PM_2.5 concentrations increased by 96.3% during FBP compared with those during non-FB period (NFBP) in 2021, while the opposite phenomenon was observed in 2022 with PM_2.5 concentrations decreasing by 56.2% because of the favorable meteorological condition during FBP in 2022. As indicators of FB, the Cl^-, K⁺, and Mg²⁺ concentrations showed an increasing trend during FBP compared with that during NFBP, both in 2021 and 2022, but had little effect on other components. The contribution of FB to PM_2.5 decreased from 68.4% in 2021 to 15.7% in 2022 based on the relative ratio method, indicating the various measures conducted by all districts and counties in Linyi helped achieve near zero fireworks emissions by 2022. Besides, the contribution of FB to PM_2.5 showed a straight-line upward trend from 19:00 on New Year's Eve, reached its peak (76.1%) at 3:00 on Lunar New Year's Day, while the highest value was only 35.0% during FBP in 2022, indicating the implementation of fireworks ban measures in Linyi achieved a good effect on pollution peak cutting. This study has emphasized the necessity of FB restricting during special holidays.

Important revelations of different degrees of COVID-19 lockdown on improving regional air quality: a case study of Shijiazhuang, China

To control the spread of COVID-19, Shijiazhuang implemented two lockdowns of different magnitudes in 2020 (lockdown I) and 2021 (lockdown II). We analyzed the changes in air quality index (AQI), PM_2.5, O₃, and VOCs during the two lockdowns and the same period in 2019 and quantified the effects of anthropogenic sources during the lockdowns. The results show that AQI decreased by 13.2% and 32.4%, and PM_2.5 concentrations decreased by 12.9% and 42.4% during lockdown I and lockdown II, respectively, due to the decrease in urban traffic mobility and industrial activity levels. However, the sudden and unreasonable emission reductions led to an increase in O₃ concentrations by 160.6% and 108.4%, respectively, during the lockdown period. To explore the causes of the O₃ surge, the major precursors NO_x and VOCs were studied separately, and the main VOCs species affecting ozone formation during the lockdown period and the source variation of VOCs were identified, and it is important to note that the relationship between diurnal variation characteristics of VOCs and cooking became apparent during the lockdown period. These findings suggest that regional air quality can be improved by limiting production, but attention should be paid to the surge of O₃ caused by unreasonable emission reductions, clarifying the control priorities for urban O₃ management.

Weather-Climate Anomalies and Regional Transport Contribute to Air Pollution in Northern China During the COVID-19 Lockdown

Two persistent and heavy haze episodes during the COVID-19 lockdown (from 20 Jan to 22 Feb 2020) still occur in northern China, when anthropogenic emissions, particularly from transportation sources, are greatly reduced. To investigate the underlying cause, this study comprehensively uses in-situ measurements for ambient surface pollutants, reanalysis meteorological data and the WRF-Chem model to calculate the contribution of NO_x emission change and weather-climate change to the "unexpectedly heavy" haze. Results show that a substantial NO_x reduction has slightly decreased PM_2.5 concentration. By contrast, the weakest East Asian winter monsoon (EAWM) in the 2019-2020 winter relative to the past decade is particularly important for haze occurrence. A warmer and moister climate is also favorable. Model results suggest that climate anomalies lead to a 25-50 μg m^-3 increase of PM_2.5 concentration, and atmospheric transport is also an important contributor to two haze episodes. The first haze is closely related to the atmospheric transport of pollutants from NEC to the south, and fireworks emissions in NEC are a possible amplifying factor that warrants future studies. The second one is caused by the convergence of a southerly wind and a mountain wind, resulting in an intra-regional transport within BTH, with a maximal PM_2.5 increment of 50-100 μg m^-3. These results suggest that climate change and regional transport are of great importance to haze occurrence in China, even with significant emission reductions of pollutants.

Fine Particulate Matter Concentrations during Independence Day Fireworks Display in the Lower Rio Grande Valley Region, South Texas, USA

Fireworks are typically discharged as a mark of celebration and joy in many societies spanning various cultures. In the United States of America, 4th July is celebrated as the Independence Day when the nation overthrew the British colonial yoke in 1776. While this day instills a sense of patriotism in every American’s heart, it is also a major PM2.5 air pollution concern. This study is first of its type in the Lower Rio Grande Valley (RGV) Region of South Texas, USA, that characterizes fine particulate matter pollution. Using a low-cost sensor (TSI BlueSky Air Quality Monitor), real-time PM2.5 measurements were assessed at eleven different locations in four different towns and cities of Lower RGV Region: Brownsville, Edinburg, Weslaco, and Port Isabel. Hourly PM2.5 concentrations from July 03–06, 2021 are presented in this research work. Intraurban PM2.5 spatial and temporal variations provide an insight on the general population’s exposure burden during the festive period. Results indicate an increase in fine particulate matter pollution across the region, but the levels do not exceed the U.S. National Ambient Air Quality Standards (NAAQS). Findings from this study would possibly help in the formulation of effective firework policies to minimize the pollution impact.

Assessment of pollution by the combustion residue and smoke of boron blended flash powder

Possible environmental effects of flash powder mixture combustion containing aluminium and boron along with other ingredients like potassium nitrate and sulphur are reported. Once the firecrackers are lighted, they burst out particulate matter and harmful gases with scintillating effect. These particulate matters and the harmful gases together make the environment fogged and get deposited on all surfaces. Recent research suggests replacing aluminium with boron to implement safety during manufacturing and to enhance performance. But the effects of the combustion residue have to be checked and compared before implementation. Hence, in this work, the possible effects of the firework mixtures particularly flash powder mixtures containing aluminium are monitored and compared with the effects of boron blended flash powder mixtures. Based on the smoke settling test, plant growth test and soil test, it is concluded that up to 12.5% of boron can be added in flash powder mixture to prevent pollution of the environment. The threshold quantity of residue without affecting the soil quality for 100 % usage of boron was found as 10 g of residue in 2 kg of soil.

Fine particles from village air in northern China in winter: Large contribution of primary organic aerosols from residential solid fuel burning

Rural residential emissions contribute significantly to regional air pollution in China, but our understanding on how residential solid fuel burning influences the village outdoor air quality is limited. In this study, we compared the fine particulate matter (PM_2.5) composition and individual particle characteristics from 11 to 18 January 2017 at a village and an urban site in northern China. At the village site, each day was divided into four periods: cooking (07:30-10:00; 16:00-17:00), daytime (10:00-16:00), heating (17:00-24:00), and midnight (00:00-07:30) periods. The highest PM_2.5 concentration occurred during the cooking period (236 ± 88 μg m^-3), which was characterized by high concentrations of K⁺ and abundant primary OM-K particles (i.e., organic matter mixed with K-salts) emitted from residential biomass burning. The second highest PM_2.5 concentration was found during the heating period (161 ± 97 μg m^-3), and the PM_2.5 contained abundant spherical primary OM particles (i.e., tarballs) emitted from residential coal burning. The primary emissions from residential solid fuel burning resulted in 75% of the village OM by mass consisting of primary OM and 67% of the village aerosol particles by number internally mixing with primary OM particles. The village PM_2.5 composition was different from that of the urban PM_2.5, with the former containing more OM (47% vs 32%) and less secondary inorganic ions (30% vs 46%). Individual primary OM-K and tarballs were abundant in the village air. These results suggest a large contribution of village residential emissions in the winter to village air pollution. Our study highlights that the residential health in villages of northern China should be paid more attention because of high PM_2.5 concentrations and abundant toxic particles during the cooking and heating periods per day in winter.

The Effects of Fireworks Discharge on Atmospheric PM2.5 Concentration in the Chinese Lunar New Year

Discharging fireworks during the Chinese Lunar New Year celebrations is a deep-rooted custom in China. In this paper, we analyze the effect of this cultural activity on PM2.5 concentration using both ground observations and satellite data. By combining remote sensing data, the problem of uneven spatial distribution of ground monitoring has been compensated, and the research time span has been expanded. The results show that the extensive firework displays on New Year's Eve lead to a remarkable increase in nationwide PM2.5 concentration, which were 159~223% of the average level, indicating the instantaneous effect far exceeds that of any other factor over the whole year. However, the averaged PM2.5 concentrations of the celebration period were 0.99~16.32 μg/m3 lower compared to the average values of the corresponding pre-celebration period and post-celebration period, indicating the sustained effect is not very significant. The implementation of firework prohibition policies can greatly reduce the instantaneous PM2.5 increase, but no obvious air quality improvement is observed over the entire celebration period. Combining these findings and the cultural significance of this activity, we recommend that this custom is actively maintained, using new technologies and scientific governance programs to minimize the negative effects.

Levels and sources of hourly PM2.5-related elements during the control period of the COVID-19 pandemic at a rural site between Beijing and Tianjin

To control the spread of the novel coronavirus disease 2019 (COVID-19) in China, many anthropogenic activities were reduced and even closed on the national scale. To study the impact of this reduction and closing down, hourly concentrations of PM2.5-related elements were measured at a rural site before (12-25 January 2020), during (26 January-9 February 2020) and after (22 March-2 April 2020) the control period when all people remained socially isolated in their homes and could not return to economic zones for work. Nine major sources were identified by the positive matrix factorization model, including fireworks burning, coal combustion, vehicle emissions, dust, Cr industry, oil combustion, Se industry, Zn smelter, and iron and steel industry. Before the control period, K, Fe, Ca, Zn, Ba and Cu were the main elements, and fireworks burning, Zn smelter and vehicle emissions provided the highest contributions to the total element mass with 55%, 12.1% and 10.3%, respectively. During the control period, K, Fe, Ba, Cu and Zn were the dominating elements, and fireworks burning and vehicle emissions contributed 55% and 27% of the total element mass. After the control period, Fe, K, Ca, Zn and Ba were the main elements, and dust and iron and steel industry were responsible for 56% and 21% of the total element mass. The increased contribution from vehicle emissions during the control period could be attributed to our sampling site being near a town hospital and the fact that the vehicle activities were not restricted. The source apportionment results were also related to air mass backward trajectories. The largest reductions of dust, coal combustion, and the industrial sources (Cr industry, Zn smelter, Se industry, iron and steel industry) were distinctly seen for northwest transport (Ulanqab) and were least significant for northeast transport (Tangshan and Tianjin).

Air quality intervention during the Nanjing youth olympic games altered PM sources, chemical composition, and toxicological responses

Ambient particulate matter (PM) is a leading global environmental health risk. Current air quality regulations are based on airborne mass concentration. However, PM from different sources have distinct chemical compositions and varied toxicity. Connections between emission control measures, air quality, PM composition, and toxicity remain insufficiently elucidated. The current study assessed the composition and toxicity of PM collected in Nanjing, China before, during, and after an air quality intervention for the 2014 Youth Olympic Games. A co-culture model that mimics the alveolar epithelium with the associated macrophages was created using A549 and THP-1 cells. These cells were exposed to size-segregated inhalable PM samples. The composition and toxicity of the PM samples were influenced by several factors including seasonal variation, emission sources, and the air quality intervention. For example, we observed a size-dependent shift in particle mass concentrations during the air quality intervention with an emphasized proportion of smaller particles (PM_2.5) present in the air. The roles of industrial and fuel combustion and traffic emissions were magnified during the emission control period. Our analyses revealed that the PM samples demonstrated differential cytotoxic potencies at equal mass concentrations between sampling periods, locations, and time of day, influenced by variations in the predominant emission sources. Coal combustion and industrial emissions were the most important sources affecting the toxicological responses and displayed the least variation in emission contributions between the sampling periods. In conclusion, emission control mitigated cytotoxicity and oxidative stress for particles larger than 0.2 μm, but there was inadequate evidence to determine if it was the key factor reducing the harmful effects of PM_0.2.

Molecular characteristics and stable carbon isotope compositions of dicarboxylic acids and related compounds in the urban atmosphere of the North China Plain: Implications for aqueous phase formation of SOA during the haze periods

In the past five years, Chinese government has promulgated stringent measures to mitigate air pollution. However, PM_2.5 levels in the China North Plain (NCP), which is one of the regions with the heaviest air pollution in the world, are still far beyond the World Health Organization (WHO) standard. To improve our understanding on the sources and formation mechanisms of haze in the NCP, PM_2.5 samples were collected during the winter of 2017 on a day/night basis at the urban site of Liaocheng, which is one of the most polluted cities in the NCP. The samples were determined for molecular distributions and stable carbon isotope compositions of dicarboxylic acids and their precursors (ketocarboxylic acids and α-dicarbonyls), levoglucosan, elemental carbon (EC), organic carbon (OC) and water-soluble organic carbon (WSOC). Our results showed that oxalic acid (C₂) is the dominant dicarboxylic acid, followed by succinic acid (C₄) and malonic acid (C₃), and glyoxylic acid (ωC₂) is the most abundant ketocarboxylic acids. Concentrations of C₂, glyoxal (Gly) and methylglyoxal (mGly) presented robust correlations with levoglucosan, suggesting that biomass burning is a significant source of PM_2.5 in the NCP. Moreover, C₂ and Gly and mGly linearly correlated with SO₄^2-, relative humidity (RH), aerosol liquid water content (LWC) as well as particle in-situ pH (pH_is), indicating that aqueous-phase oxidation is the major formation pathway of these SOA, and is driven by acid-catalyzed oxidation. Concentrations and relative abundances of secondary species including SNA (SO₄^2-, NO₃^- and NH₄⁺), dicarboxylic acids, and aerosol LWC in PM_2.5 are much higher in the haze periods than in the clean periods, suggesting that aqueous reaction is a vital role in the haze formation. In comparison with those in the clean periods, stable carbon isotopic compositions (δ¹³C) of major dicarboxylic acids and related SOA and the mass ratios of C₂/diacids, C₂/Gly and C₂/mGly are higher in the haze periods, indicating that haze particles were more aged and enriched in secondary species.

Effects of fireworks on particulate matter concentration in a narrow valley: the case of the Medellín metropolitan area

The extensive use of fireworks generates large amounts of pollutants, deteriorating air quality and potentially causing adverse health impacts. In Medellín and its metropolitan area, although fireworks are banned during December, their use is widespread during the Christmas season, particularly during the midnight of November 30 (La Alborada) and New Year's Eve (NYE). It is therefore essential to assess the effects of these celebrations on air quality in the region. Air-quality data from the official monitoring network and a low-cost particulate matter (PM) citizen science project, backscattering intensity (BI) retrievals from a ceilometer network, potential temperature from a microwave radiometer, and information from a radar wind profiler provide an excellent platform to study the spatio-temporal distribution of contaminants resulting from the La Alborada and NYE celebrations. Substantial increases in PM2.5 and PM10 mass concentrations due to La Alborada and NYE, ranging in some cases from 50 to 100 μgm^-3, are observed in the Aburrá Valley and particularly in the densely populated communes of Medellín, with most concentration changes corresponding to ultrafine and fine particles. The PM increments resulting from fireworks show almost no increase in the net amount of black carbon in the atmosphere. Ceilometer BI profiles show a substantial change immediately after the La Alborada and NYE midnights, confined to the atmospheric boundary layer (ABL). Strong thermal inversions lead to fairly homogeneous increments in BI within the ABL, lasting until the onset of the convective boundary layer. In contrast, weak thermal inversions lead to rapid dispersion of aerosols, allowing them to episodically escape above the ABL.

Profiles, source identification and health risks of potentially toxic metals in pyrotechnic-related road dust during Chinese New Year

Potentially toxic metal (PTM) pollution in road dust is of great concern, however, our understanding of PTMs released by pyrotechnic displays and their adverse impacts on human health in road dust is limited. Here, we studied PTM pollution levels and Pb isotope signatures in pyrotechnic ash and road dust (aged dust and pyrotechnic-influenced dust) samples from eight cities in China during Chinese New Year and carried out a human health risk assessment. Pyrotechnic ash had higher values of Cr, Co, Ni, Cu, Zn, As, Sr and Pb but lower values of Mn and Cd than Chinese background soil. Pyrotechnic-influenced dust had significantly higher Cu and Cr values than aged dust, with enrichment of Sr, Cu, Pb, Cr and Ni in road dust after pyrotechnic displays. Both ²⁰⁸Pb/²⁰⁶Pb and Sr values were used to confirm the presence of pyrotechnic ash in road dust. A positive matrix factorization demonstrated that pyrotechnic events contributed 70.1%, 50.4%, 36.6% and 35.5% of the Sr, Cu, Cr and Pb values to these road dust, respectively. We found that non-carcinogenic and carcinogenic risks related to PTMs in road dust were at safe levels during the Chinese New Year, although both risks were elevated following pyrotechnic events. Typically, PTM pollutants related to pyrotechnic events contributed 33.99% to non-carcinogenic and 21.83% to carcinogenic risks, suggesting that more attention needs to be paid to this source of PTM pollution in China. Current results improve our understanding of PTM pollution in pyrotechnic-influenced road dust and health risks related to pyrotechnic displays in China.

PM2.5-bound polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs (NPAHs) in rural and suburban areas in Shandong and Henan Provinces during the 2016 Chinese New Year's holiday

Eighteen polycyclic aromatic hydrocarbons (PAHs) and fourteen nitrated PAHs (NPAHs) in PM_2.5 samples were collected during the 2016 Chinese New Year's holiday (CNY) at one suburban and three rural sites in Shandong and Henan Provinces. The PAH and NPAH concentrations were highest at the suburban site. The rural PAH concentrations in Qingzhou (QZ), Heze (HZ), and Liaocheng (LC) were higher than those measured at many other urban sites, indicating that PAHs pollution was notably higher in the suburban and rural sites during this festive period. Elevated PAH concentrations were observed during fireworks periods, but fireworks burning was not a significant or direct PAHs or NPAHs source based on molecular profiles and diagnostic ratios. The measured PAHs and NPAHs at the sampling sites mainly originated from coal and biomass burning. The increased concentrations during CNY's Eve may be related to behavioural changes during the period. Secondary formation of NPAHs mainly occurred via OH radical chemistry at all four sites. Fireworks burning did not increase secondary formation of NPAHs. ∑BaP_eq concentrations exhibited strong correlations with PAHs concentrations, and the highest and lowest concentrations were observed in QZ and Xiping (XP), respectively. The incremental lifetime cancer risk (ILCR) was calculated to be between 10^-6 and 10^-4 for 1-70 years old persons, with the highest risks observed in the adult (30-70 years) and the toddler (1-6 years) groups.

Impact of New Year's Eve fireworks on the size resolved element distributions in airborne particles

New Year's Eve fireworks represent one of the most unusual atmospheric pollution events in the course of a year. A majority of particles aerosolized by burning of fireworks consist of metals and their compounds used in firework displays. In this study, ambient particulate matter was sampled using a 14 stage cascade impactor in two European cities during turn of the years 2016/17 and 2017/18. Concentrations of 33 elements were determined by inductively coupled plasma mass spectrometry. To assess the impact of New Year's Eve fireworks on ambient air quality, chemically resolved size distributions of particles with diameters between 15 nm and 10 μm collected during fireworks episodes were compared to ones collected in normal winter weeks. For some metals a distinct shift of their concentration maximum related to fireworks could be observed, which is in between the maxima for accumulation and coarse mode particles. Concentrations of these elements (Sr, Ba, Mg, Bi, Al, Cu and K) were also higher during weeks with fireworks episodes than during control weeks. Although New Year's Eve fireworks only take place once a year, these results show that air pollution caused by fireworks can be a potential health risk, especially for people with pre-existing diseases.

Levels and health risks of PM2.5-bound toxic metals from firework/firecracker burning during festival periods in response to management strategies

Daily PM_2.5 was collected in the periods before, during and after the Chinese Spring Festival (CSF) in both 2016 and 2018 to clarify the annual variation in the concentrations and health risks of toxic metals under different firework/firecracker (FF) management strategies. PM_2.5 and bound metals all decreased during the CSF from 2016 to 2018. According to relative abundance analysis, toxic metals, i.e., Ba, Pb, Cu and Cr, showed obvious peak concentrations and abundance levels on intensive FF burning days, i.e., New Year's Eve, Chinese New Year and the Lunar Festival. In both CSF periods, three sources of toxic metals, namely, FF burning, coal combustion, and resuspended dust and vehicle emissions, were identified by positive matrix factorization (PMF). Among them, the mass contribution of FF decreased from 0.83 μg m^-3 (11%) in the 2016 CSF to 0.23 μg m^-3 (9.0%) in the 2018 CSF. The FF-attributed noncancer and cancer risks due to metals for residents under long-term exposure were 0.02 (19.9%) and 1.76 × 10^-7 (17.9%) in the 2016 CSF and 0.01 (20.2%) and 8.59 × 10^-8 (14.7%) in the 2018 CSF. Although a policy shift from "restriction" to "prohibition" regarding FF has indeed decreased toxic metal concentrations and health risk, Cr(VI) and Ba should be examined more closely in the future because they have become dominant contributors to cancer risk and noncancer risk, respectively.

Characterization of lead-containing atmospheric particles in a typical basin city of China: Seasonal variations, potential source areas, and responses to fireworks

Lead (Pb) in individual aerosol particles was measured using a single particle aerosol mass spectrometer at an urban site in Chengdu, a typical basin city of China, for four one-month periods in 2016-2017 - one period for each season. The highest mass concentrations of particulate matter (PM) and gaseous species (CO, NO, NO₂, and SO₂) were observed in winter. Cluster analysis was applied to Pb-containing particles, and eight major classes were identified based on mass spectral features. The contribution of these classes to the total Pb-containing particles varied seasonally - for example, Pb-nitrate (PbNO₃) particles showed a higher contribution in spring and winter (47%), while Pb-sulfate (PbSO₄) particles exhibited a higher contribution in summer and autumn (14%-19%). The size range of particles also changed with seasons as a result of different sources and formation mechanisms under different climatic conditions. A weighted potential source contribution function (WPSCF) analysis suggested that the potential source areas of Pb-containing particles were mainly located to the northeast, east, southeast, and south of Chengdu, and their contribution intensity and coverage area significantly varied in the four seasons. Although almost all pollutants decreased during the Spring Festival holiday (SF) period, fireworks caused the most serious PM and SO₂ pollution episodes during the whole study period. During the SF period, the contributions of industrial and traffic-related particles (Pb-organic + elemental carbon (PbOE) and PbNO₃ particles) decreased, whereas those of Pb-chloride (PbCl), Pb-metal (PbM), and Pb-sulfate + nitrate (PbSN) particles increased due to fireworks. Results from this study may provide valuable information for a deeper understanding of Pb in particles and evaluation its impacts on atmospheric environment and human health.

Air pollution during New Year's fireworks and daily mortality in the Netherlands

Short-term exposure to air pollution has been associated with cardiovascular and respiratory mortality and morbidity. Little is known about associations between air pollution caused by firework events and daily mortality. We investigated whether particulate matter from fireworks during New Year’s celebrations was associated with daily mortality. We analyzed the celebrations of the years 1995–2012. PM₁₀ concentrations increased dramatically during the firework events. Countrywide, the daily average PM₁₀ concentrations from 27–30 December was 29 μg/m³ and increased during the first hour of the New Year by 277 μg/m³. In the more densely populated areas of the Netherlands the increase was even steeper, 598 μg/m³ in the first hour of the New Year. No consistent associations were found using linear regression models between PM₁₀ concentrations during the first six hours of 1 January and daily mortality in the general population. Yet, using a case-crossover analysis firework-days and PM₁₀ concentrations were associated with daily mortality. Therefore, in light of the contradictory results obtained with the different statistical analyses, we recommend further epidemiological research on the health effects of exposure to firework emissions.

Trace elements in PM2.5 in Shandong Province: Source identification and health risk assessment

The chemical compositions in PM_2.5 in metropolitan areas have obtained lots of attentions, of which concerns of airborne trace elements are relatively lacking. Here, PM_2.5 samples were collected simultaneously in one year at four urban sites (Zibo (ZB), Zaozhuang (ZZ), Qingdao (QD) and Jinan (JN (Shandong University)), and a rural site (JN (Miaopu)) in Shandong province. 25 elements (Al, Na, Cl, Mg, Si, S, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Se, Br, Sr, Cd, Ba and Pb) in PM_2.5 were measured by wavelength dispersive X-ray fluorescence spectrometer (WDXRF). Most trace elements (Al, Na, Cl, Mg, Si, Ca, Ti, Mn, Fe, Co, Ni, As, Se, Br, Cd, Ba and Pb) exhibited the highest levels at ZB and the lowest at QD. Meanwhile, they presented obvious seasonal variations with the highest concentrations in winter or spring and the lowest in summer. S and K were the most abundant elements in the area. In the non-crustal trace metal elements, Zn, Pb and Mn presented the highest concentrations. Positive matrix factorization (PMF) modeling revealed that secondary formation, coal combustion and industry emissions were the main sources in the region. The health risk assessments suggested that at the five sites Cd (diet) for adults, Pb and Co for children, and Mn (diet) for both adults and children (at ZB and SDU sites) had non-carcinogenic risks. As and Pb for adults and children existed carcinogenic risks, especially Pb for children. The sources of these elements with health risks were further explored. Notably, Cd, As and Pb should be paid special attention in the area due to their high concentrations in aerosol water exceeding the acceptable health risks, especially Pb.