Environmental science: atmospheres最新文献

{"title":"Nocturnal vertical gradients in O3, PAN and PAA in a boreal forest: the role of chemical reactions, deposition and entrainment","authors":"Simone T. Andersen, Carolina Nelson, Laura Wüst, Patrick Dewald, Gunther N. T. E. Türk, Jan Schuladen, Horst Fischer, Mikael Ehn, Tuukka Petäjä, Üllar Rannik, Ilona Ylivinkka, Lauri R. Ahonen, Robby Rynek, Helko Borsdorf, Thomas Mayer, Jos Lelieveld and John N. Crowley","doi":"10.1039/D5EA00159E","DOIUrl":"https://doi.org/10.1039/D5EA00159E","url":null,"abstract":"<p >The complex interplay between different processes (physical losses, chemical losses and entrainment) defines the vertical gradient of many trace gases in forested environments. Despite this, height-resolved measurements of trace gases within a forest canopy are scarce. We present measurements of O<small>₃</small>, PAN (peroxy acetyl nitric anhydride, CH<small>₃</small>C(O)OONO<small>₂</small>), and PAA (peroxy acetic acid, CH<small>₃</small>C(O)OOH) at 6 heights between 1 and 28 m above and below the canopy at the SMEAR II site in the Finnish boreal forest. Through analysis of O<small>₃</small>, PAN, and PAA nocturnal time-series we derived their height-dependent net loss rate coefficients. The net lifetimes of O<small>₃</small>, PAN and PAA were highly variable with values of 1.5–42 h, 1.0–29 h, and 0.7–15 h, respectively, with the shortest lifetimes often measured at the lowest heights. The relative loss rates of PAN or PAA compared to O<small>₃</small> (<em>k</em><small>_PAN</small>/<em>k</em><small>_{O<small>₃</small>}</small> and <em>k</em><small>_PAA</small>/<em>k</em><small>_{O<small>₃</small>}</small>) varied between 1.0–3.0 (85% of the measurements) and 1.0–5.0 (78% of the measurements) with medians of 1.7 and 2.4, respectively. The physical loss of O<small>₃</small>, PAN and PAA was the major loss process (&gt;90%), with chemical losses playing only a minor role. Entrainment significantly compensated for the physical and chemical losses and led to reduced net loss values of each trace gas, with exceptions encountered on a few nights when the sub-canopy and above-canopy air masses were decoupled as a result of <em>e.g.</em> low wind speed and friction velocity. Our vertical profiles of O<small>₃</small>, PAN, and PAA reveal the complex interplay of boundary layer dynamics and chemistry at this forested location.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 4","pages":" 496-514"},"PeriodicalIF":3.5,"publicationDate":"2026-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2026/ea/d5ea00159e?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734725","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Correction: Yields of perfluorocarboxylic acids from the atmospheric oxidation of Montreal Protocol related gases","authors":"M. P. Sulbaek Andersen, T. J. Wallington, J. B. Burkholder, S. Madronich, M. L. Hanson, D. Van Hoomissen and K. R. Solomon","doi":"10.1039/D6EA90009G","DOIUrl":"https://doi.org/10.1039/D6EA90009G","url":null,"abstract":"<p >Correction for ‘Yields of perfluorocarboxylic acids from the atmospheric oxidation of Montreal Protocol related gases’ by M. P. Sulbaek Andersen <em>et al.</em>, <em>Environ. Sci.: Atmos.</em>, 2026, https://doi.org/10.1039/D5EA00179J.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 4","pages":" 607-608"},"PeriodicalIF":3.5,"publicationDate":"2026-03-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2026/ea/d6ea90009g?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734786","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Oxidative potential of fine particle emissions of a residential wood-fired boiler","authors":"Marie Khedari, Audrey Villot, Joulanda Taha, Olli Sippula, Pasi Jalava and Yves Andres","doi":"10.1039/D5EA00177C","DOIUrl":"https://doi.org/10.1039/D5EA00177C","url":null,"abstract":"<p >Biomass combustion emits significant amounts of airborne particles, which have been recognized for their environmental and health risks for decades. Oxidative potential (OP) is one of the health-relevant metrics introduced frequently to assess airborne particles in recent years. This study investigates the OP offresh particulate matter with an equivalent aerodynamic diameter of less than or equal to 1 µm (PM<small>₁</small>) emitted from a residential biomass boiler (15 kW). Four biomasses, including hardwood chips, softwood chips, hardwood pellets, and softwood pellets, were studied. The sampled PM<small>₁</small> was characterized for its physicochemical properties and analyzed with two OP assays, including ascorbic acid (AA) and dithiothreitol (DTT). The average intrinsic OP<small>^AA</small><small>_m</small> ranged from 0.005 to 0.018 nmol min<small>⁻¹</small> µg<small>⁻¹</small>, and volume-normalized OP<small>^AA</small><small>_v</small> was 304.0 to 583.5 nmol min<small>⁻¹</small> m<small>⁻³</small>. For DTT assay, the range was 0.0002 to 0.004 nmol min<small>⁻¹</small> µg<small>⁻¹</small> for OP<small>^DTT</small><small>_m</small>, and 20.9 to 68.7 nmol min<small>⁻¹</small> m<small>⁻³</small> for OP<small>^DTT</small><small>_v</small>. More importantly, biomass types with high combustion-emitted PM emissions did not necessarily exhibit high OP, highlighting particle chemical composition as a key determinant of OP. Significant correlations were observed between the organic carbon (OC) fraction and intrinsic OP, underscoring the role of particulate organic components in driving OP from biomass combustion emissions. These findings emphasize the importance of multi-assay OP approaches and provide critical insight into the contribution of combustion emissions from different biomass fuels to ambient air.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 4","pages":" 515-532"},"PeriodicalIF":3.5,"publicationDate":"2026-03-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2026/ea/d5ea00177c?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734726","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The effect of surface sink saturation and emission altitude on hydrogen's atmospheric impact","authors":"Evan M. Gibney, Sebastian D. Eastham, Florian Allroggen and Raymond L. Speth","doi":"10.1039/D5EA00139K","DOIUrl":"https://doi.org/10.1039/D5EA00139K","url":null,"abstract":"<p >Hydrogen is often viewed as a potential component of a decarbonized transportation system, offering the ability to eliminate direct CO<small>₂</small> emissions while being produced with low lifecycle greenhouse gas emissions. However, direct emissions of hydrogen can trigger indirect climate and air quality effects which may partially or fully offset these benefits. We use the GEOS-Chem High Performance (GCHP) global chemistry-transport model to investigate how surface sink representation and emission altitude influence the climate impact of hydrogen emissions, specifically with respect to high-altitude emissions from prospective future hydrogen aircraft. We show that if the soil sink becomes saturated and can no longer increase uptake rates as atmospheric hydrogen concentrations rise, the perturbation lifetime of hydrogen increases, leading to a 3.8-fold increase in hydrogen's climate impact over 100 years compared to an unsaturated sink. We demonstrate that if the soil sink is unsaturated, hydrogen emitted at commercial aircraft cruise altitudes (∼11 km) has a greater climate impact than equivalent surface emissions. The magnitude of this additional impact varies between 8% over a 20-year horizon to 13% over 100 years. This altitude sensitivity results from the vertical separation between high-altitude hydrogen emissions and the soil sink, which increases the likelihood of removal by OH. Our findings highlight the need to prioritize mitigation of high-altitude hydrogen emissions, such as those from potential future hydrogen-fueled aircraft, compared to surface hydrogen emissions. More broadly, they reveal the limitations of fixed-boundary condition models to capture these mechanisms, underscoring the importance of transitioning to surface sink representations that can capture dynamic soil uptake responses. Constraining the real-world behavior of the soil sink remains a key research priority for accurately assessing hydrogen's climate impacts.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 4","pages":" 595-606"},"PeriodicalIF":3.5,"publicationDate":"2026-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2026/ea/d5ea00139k?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pre-existing particle composition controls the initial viscosity and aging of α-pinene-derived secondary organic aerosol.","authors":"Katherine R A Kolozsvari, Natasha M Garner, David M Bell, Jens Top, Markus Ammann, Andrew P Ault","doi":"10.1039/d6ea00006a","DOIUrl":"10.1039/d6ea00006a","url":null,"abstract":"<p><p>Secondary organic aerosol (SOA) is a significant contributor to the global burden of fine particulate matter, which impacts both climate and health. α-Pinene is a widely-studied volatile organic compound (VOC) with high global emissions and SOA-forming potential. However, the vast majority of SOA forms on preexisting particles whose composition leads to different molecular species and physical properties. Understanding the viscosity of SOA-containing particles is critical to predicting their atmospheric behavior, as it influences heterogeneous chemistry, particle growth, and particle aging. The viscosity of SOA can range over many orders of magnitude from liquid (<10² Pa s) to viscous to glassy (>10¹² Pa s). Nanothermal analysis (NanoTA) measures single particle melting temperatures (<i>T</i> _m) for submicron particles, which can be converted to glass transition temperatures (<i>T</i> _g), viscosities, and, ultimately, mixing time scales. In this study, we directly measured the <i>T</i> _m of α-pinene SOA formed with no seeds, ammonium sulfate seeds, and Fe-containing ammonium sulfate seeds, both before and after UV exposure. We compare these to modeled viscosities based on chemical composition measurements of the bulk aerosol. The median viscosity of measured particles was 1-3 orders of magnitude more viscous than predicted by existing models for all conditions except those of freshly-emitted, unseeded SOA. After UV exposure, the <i>T</i> _m values for all seed conditions converged, indicating that aged SOA viscosity was less dependent on the initial seed. These results indicate the importance of pre-existing seed particles for initial SOA viscosity and that this viscosity evolves during a particle's atmospheric lifetime.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2026-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13019859/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147576462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantification, diel variation and photochemistry of inorganic chlorine trace gases in continental Germany","authors":"Lasse Moormann, John N. Crowley, Friederike Fachinger and Frank Drewnick","doi":"10.1039/D5EA00142K","DOIUrl":"https://doi.org/10.1039/D5EA00142K","url":null,"abstract":"<p >Understanding the sources, distribution, and lifetime of inorganic chlorine-containing trace gases is crucial to assessing their tropospheric impacts. We report <em>in situ</em> measurements of Cl<small>₂</small>, HOCl, ClNO<small>₂</small>, and ClONO<small>₂</small> using iodide chemical ionization mass spectrometry during a 2.5-week campaign in June 2024 at a rural continental site in central Germany. Air masses that had passed over “marine-anthropogenic” regions (≈400 km distant) showed significantly higher mixing ratios of chlorine-containing gases than “continental-unpolluted” air masses. From the marine-anthropogenic period, we provide the first quantitative observations of ClONO<small>₂</small> in the lower troposphere (up to 59.8 pptv during daytime). Persistent nonzero ClONO<small>₂</small> at night implies a non-photochemical source of ClONO<small>₂</small> or its precursor ClO, and/or that heterogeneous loss is slower than laboratory uptake coefficients suggest. ClNO<small>₂</small> levels were consistent with production <em>via</em> N<small>₂</small>O<small>₅</small> uptake on chloride-containing particles; both ClNO<small>₂</small> and Cl<small>₂</small> were enhanced when O<small>₃</small>-/N<small>₂</small>O<small>₅</small>-rich air entrained into the nocturnal boundary layer. Photolysis of ClNO<small>₂</small>, Cl<small>₂</small>, and HOCl yielded mean maximum Cl atom production rates of 1.0 × 10<small>⁶</small> cm<small>⁻³</small> s<small>⁻¹</small> under marine-anthropogenic influenced air and 1.6 × 10<small>⁵</small> cm<small>⁻³</small> s<small>⁻¹</small> under continental-unpolluted conditions. In the early morning, Cl production (due to ClNO<small>₂</small> photolysis) exceeded primary–OH production from O<small>₃</small> photolysis, while after noon HOCl photolysis was the dominant Cl source. At low solar zenith angles, HOCl photolysis contributed up to 40% of primary OH. These measurements indicate that Cl atoms can strongly influence hydrocarbon oxidation in similar rural regions, with potential regional and global implications (of up to 15%) for the methane lifetime.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 4","pages":" 579-594"},"PeriodicalIF":3.5,"publicationDate":"2026-02-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2026/ea/d5ea00142k?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734784","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Yields of perfluorocarboxylic acids from the atmospheric oxidation of Montreal Protocol related gases","authors":"M. P. Sulbaek Andersen, T. J. Wallington, J. B. Burkholder, S. Madronich, M. L. Hanson, D. Van Hoomissen and K. R. Solomon","doi":"10.1039/D5EA00179J","DOIUrl":"https://doi.org/10.1039/D5EA00179J","url":null,"abstract":"<p >We present here a systematic evaluation of the molar yields of trifluoroacetic acid (TFA), perfluoropropanoic acid (PFPrA), and perfluorobutanoic acid (PFBA) from the atmospheric degradation of gases relevant to the Montreal Protocol and its Amendments. The yields are dependent on the molecular structure of the parent compound and the primary degradation products and radical intermediates formed. We incorporate new data into the Tropospheric Ultraviolet Visible (TUV) model and discuss how recent studies improve our understanding of the relative importance of the photochemical pathways for perfluoroaldehydes, C<small>_<em>x</em></small>F<small>_{2<em>x</em>+1}</small>C(O)H, which are key degradation products from some chlorofluorocarbon (CFC) replacement compounds. We identify areas for further research that could advance our understanding of the environmental fate of precursors to short-chain length perfluorocarboxylic acids.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 4","pages":" 473-483"},"PeriodicalIF":3.5,"publicationDate":"2026-02-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2026/ea/d5ea00179j?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Vertical profiles of NO3 reactivity within the surface layer of a boreal forest","authors":"Patrick Dewald, Simone T. Andersen, Gunther N. T. E. Türk, Laura Wüst, Carolina Nelson, Jan Schuladen, Mikael Ehn, Tuukka Petäjä, Ilona Ylivinkka, Lauri R. Ahonen, Horst Fischer, Jos Lelieveld and John N. Crowley","doi":"10.1039/D5EA00153F","DOIUrl":"https://doi.org/10.1039/D5EA00153F","url":null,"abstract":"<p >The reaction of the nitrate radical (NO<small>₃</small>) with biogenic volatile organic compounds (BVOC) in the atmosphere is a significant source of secondary organic aerosols and can affect the reactive nitrogen budget. Field studies dedicated to NO<small>₃</small>-BVOC interaction on elevated platforms have highlighted vertical variability in both NO<small>₃</small> and BVOC mixing ratios. While vertical profiles of NO<small>₃</small> in the upper parts of the troposphere have been studied extensively, height-resolved measurements within the surface layer of BVOC-dominated areas, such as forests, are scarce. During the “Biosphere-Atmosphere Interactions and the Reactive Nitrogen Budget: Vertical Profiles of Key Species” (BAIRN-VIP) campaign, we measured vertical profiles of (B)VOC-induced NO<small>₃</small> reactivity (<em>k</em><small>^VOC</small>) along with the NO<small>₃</small> precursors nitrogen dioxide (NO<small>₂</small>) and ozone (O<small>₃</small>) at five heights below the canopy (1–16 m) as well as at one height above it (28 m) in order to assess the vertical gradients of both NO<small>₃</small> and BVOCs in the boreal forest of Hyytiälä, Finland. We find that the stability of the nocturnal boundary layer and decoupling of the sub-canopy flow are the main drivers of the vertical gradients in <em>k</em><small>^VOC</small>. Steady-state calculations indicate that NO<small>₃</small> concentrations on the order of pptv are found exclusively above the canopy during strongly decoupled nights, with BVOCs as the only NO<small>₃</small> sink at heights above 4 m. During the day, BVOCs contribute, on average, 40–60% to the loss of NO<small>₃</small> along the profile. Our results indicate that single-height field measurements of NO<small>₃</small> are insufficient to explain nighttime oxidation chemistry under decoupled conditions.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 4","pages":" 551-564"},"PeriodicalIF":3.5,"publicationDate":"2026-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2026/ea/d5ea00153f?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quantifying sensitivity of PM2.5 mass to ammonia and nitrate availability in Hong Kong based on four-year hourly measurements","authors":"Zijing Zhang and Jian Zhen Yu","doi":"10.1039/D5EA00114E","DOIUrl":"https://doi.org/10.1039/D5EA00114E","url":null,"abstract":"<p >Ammonium and nitrate are major components of PM<small>_2.5</small>, and their fractional contributions to urban PM<small>_2.5</small> in China have increased in recent years, largely due to successful sulfate reductions. Owing to their semi-volatile nature, ammonium and nitrate in PM<small>_2.5</small> are strongly affected by gas–particle partitioning, which depends on temperature, relative humidity, and the ionic composition of PM<small>_2.5</small>. Quantifying the sensitivity of PM<small>_2.5</small> mass to precursor availability under locale-specific atmospheric conditions is therefore essential for air quality management. In this study, we analyzed four years (2013–2017) of hourly concentrations of inorganic ions and their gaseous precursors at an urban site in Hong Kong. We estimated aerosol water content (AWC) and aerosol pH and conducted a detailed seasonal analysis. Our results revealed distinct sensitivities of PM<small>_2.5</small> to ammonia and nitrate availability, modulated by aerosol pH and AWC. In fall, sulfate-dominated PM<small>_2.5</small> exhibited low sensitivity to HNO<small>₃</small>, while in winter, increased partitioning ratios led to higher PM<small>_2.5</small> sensitivity to HNO<small>₃</small>. Quantitative assessment showed that reductions in water-soluble inorganic PM were proportional to decreases in total nitrate (TNO<small>₃</small>, including gaseous HNO<small>₃</small> and particulate nitrate) and sulfate, but exhibited a parabolic relationship with reductions in total ammonia (TNH<small>₃</small>, including gaseous NH<small>₃</small> and particulate ammonium). As TNH<small>₃</small> levels are further reduced, the sensitivity of PM<small>_2.5</small> to NH<small>₃</small> would increase. Our findings highlight the importance of synergistic reduction of NH<small>₃</small> and NO<small>_<em>x</em></small> emissions in effectively mitigating PM<small>_2.5</small> pollution. This analysis provides valuable insights to inform the development of targeted, integrated air quality management strategies for urban environments.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 4","pages":" 565-578"},"PeriodicalIF":3.5,"publicationDate":"2026-02-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2026/ea/d5ea00114e?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734783","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Evaluating the effects of COVID-19 lockdowns on air quality across some African countries","authors":"Zizhen Han, Yuqiang Zhang, Zhou Liu, Kexin Zhang, Stanley Numbonui Tasheh, Narcisse Tchinda Tsona, Zhuyi Wang, Bin Luo, Likun Xue and Xinfeng Wang","doi":"10.1039/D5EA00111K","DOIUrl":"https://doi.org/10.1039/D5EA00111K","url":null,"abstract":"<p >The COVID-19 lockdown served as a pivotal moment to analyze significant changes in air quality due to unprecedented reductions in emissions across major African countries. This study assesses the alterations in air quality, focusing on key pollutants such as CO, NO<small>₂</small>, O<small>₃</small>, SO<small>₂</small> and aerosol particles during the lockdown period in 2020. Utilizing chemical reanalysis data from the state-of-the-art multi-component satellite data assimilation system at the Jet Propulsion Laboratory, quarterly anomalies were calculated for March to May (MAM) and June to August (JJA). The analysis reveals a significant decline in CO, NO<small>₂</small>, O<small>₃</small> and nitrate aerosols across most African nations, with more pronounced decreases observed during the JJA period. However, notable discrepancies emerged: quarterly dual anomalies indicated a reduction in NO<small>₂</small> and SO<small>₂</small> levels in Northern Africa, while quarterly anomalies suggested an increase, indicating that containment policies affected these trends. In Southern Africa (SA), both quarters witnessed increases in SO<small>₂</small> levels, likely due to relaxed restrictions and heightened energy demands. Additionally, the rise in O<small>₃</small> levels in SA may be associated with the decrease in NO<small>₂</small>. The increase in sulfate and ammonium aerosols in Northern and Southern Africa is likely attributed to dust events and elevated residential emissions, respectively. The findings from this study highlight that air quality changes are influenced by a combination of natural and anthropogenic factors, stressing the urgent need for stricter emission standards for coal-fired plants and the promotion of clean energy initiatives throughout African countries.</p>","PeriodicalId":72942,"journal":{"name":"Environmental science: atmospheres","volume":" 4","pages":" 533-550"},"PeriodicalIF":3.5,"publicationDate":"2026-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://pubs.rsc.org/en/content/articlepdf/2026/ea/d5ea00111k?page=search","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147734727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}