Impacts of Diwali fireworks on aerosol levels, composition, chemistry, and toxicity: Insights from a combined indoor-outdoor study

Impacts of Diwali fireworks on aerosol levels, composition, chemistry, and toxicity: Insights from a combined indoor-outdoor study | Research Square window.SnipcartSettings = { analytics: { enabled: false } }; (function() { var accessVector = localStorage.getItem('access_vector') || ''; window.dataLayer = window.dataLayer || []; if (accessVector) { window.dataLayer.push({ user: { profile: { profileInfo: { snid: accessVector } } } }); } })(); (function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='https://www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-K279D39R'); Browse Preprints In Review Journals COVID-19 Preprints AJE Video Bytes Research Tools Research Promotion AJE Professional Editing AJE Rubriq About Preprint Platform In Review Editorial Policies Our Team Advisory Board Help Center Sign In Submit a Preprint Cite Share Download PDF Research Article Impacts of Diwali fireworks on aerosol levels, composition, chemistry, and toxicity: Insights from a combined indoor-outdoor study Debayan Mandal, Abhishek Chakraborty, Vidit Parkar This is a preprint; it has not been peer reviewed by a journal. https://doi.org/ 10.21203/rs.3.rs-8473668/v1 This work is licensed under a CC BY 4.0 License Status: Posted Version 1 posted You are reading this latest preprint version Abstract We investigated PM 2.5 levels and chemical composition during the Diwali period at the residential area of the Indian Institute of Technology Bombay (IITB) by sampling at the Hostel 14 terrace (outdoor) and an adjacent residential room (indoor). The average PM 2.5 in the indoor and outdoor locations increased by approximately two times during Diwali (Di) compared to Pre-Diwali (PrD) levels, and remained elevated (~15%) even in the Post-Diwali (PoD) phase, indicating prolonged pollution effects. Among OC–EC fractions, EC1 increased sharply during Di by ~447% indoors and 319% outdoors, highlighting the strong influence of firecracker combustion. Potassium (K⁺), a marker of pyrotechnic activity, also surged during Diwali by ~184% indoors and ~68% outdoors compared to PrD. During Di, sulfate dominated the water-soluble anions. The ammonium to sulfate+nitrate ratio dropped below 1 during Diwali, suggesting enhanced aerosol acidity due to incomplete neutralization of acidic species. HR-ToF-AMS analysis revealed the steeper slope between fC 2 H 3 O + and fCO 2 + [ C 2 H 3 O + (m/z=43) , and CO 2 + (m/z=44) to Organic Aerosol ratio] during Di time, indicating rapid decarboxylation or enhanced fragmentation. Volume-normalized oxidative potential (OP DTTv ) reached 8.46 (±2.25) and 8.98 (±2.52) nmol min -1 m -3 indoor, and outdoor, respectively, reflecting a ~270% ,and ~216% enhancement relative to PrD. These results demonstrate that short-term pyrotechnic activities during Diwali substantially altered aerosol chemistry, carbonaceous composition, and oxidative potential, even within a relatively low-traffic academic–residential environment. The average number of passively smoked cigarettes (PSC) reached more than 20 for cardiovascular mortality during the Di period. Fireworks PM2.5 composition organic aerosol evolution oxidative potential HR-ToF-AMS Full Text Additional Declarations No competing interests reported. Supplementary Files P3EMADiwaliFireworksSI.docx Cite Share Download PDF Status: Posted Version 1 posted You are reading this latest preprint version Research Square lets you share your work early, gain feedback from the community, and start making changes to your manuscript prior to peer review in a journal. As a division of Research Square Company, we’re committed to making research communication faster, fairer, and more useful. We do this by developing innovative software and high quality services for the global research community. Our growing team is made up of researchers and industry professionals working together to solve the most critical problems facing scientific publishing. Also discoverable on Platform About Our Team In Review Editorial Policies Advisory Board Help Center Resources Author Services Accessibility API Access RSS feed Manage Cookie Preferences © Research Square 2026 | ISSN 2693-5015 (online) Privacy Policy Terms of Service Do Not Sell My Personal Information {"props":{"pageProps":{"initialData":{"identity":"rs-8473668","acceptedTermsAndConditions":true,"allowDirectSubmit":true,"archivedVersions":[],"articleType":"Research Article","associatedPublications":[],"authors":[{"id":572477759,"identity":"c4a95588-84c5-40a0-bf8e-381f6ce0b1f7","order_by":0,"name":"Debayan Mandal","email":"","orcid":"","institution":"Indian Institute of Technology Bombay","correspondingAuthor":false,"prefix":"","firstName":"Debayan","middleName":"","lastName":"Mandal","suffix":""},{"id":572477760,"identity":"00eb8535-f644-45d9-8e7e-a519b675a118","order_by":1,"name":"Abhishek 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","fulltext":[],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":false,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":true,"highlight":"","institution":"","isAcceptedByJournal":false,"isAuthorSuppliedPdf":true,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":true,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true},"keywords":"Fireworks, PM2.5 composition, organic aerosol evolution, oxidative potential, HR-ToF-AMS","lastPublishedDoi":"10.21203/rs.3.rs-8473668/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-8473668/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eWe investigated PM\u003csub\u003e2.5 \u003c/sub\u003elevels and chemical composition during the Diwali period at the residential area of the Indian Institute of Technology Bombay (IITB) by sampling at the Hostel 14 terrace (outdoor) and an adjacent residential room (indoor). The average PM\u003csub\u003e2.5 \u003c/sub\u003e\u0026nbsp;in the indoor and outdoor locations increased by approximately two times during Diwali (Di) compared to Pre-Diwali (PrD) levels, and remained elevated (~15%) even in the Post-Diwali (PoD) phase, indicating prolonged pollution effects. Among OC–EC fractions, EC1 increased sharply during Di by ~447% indoors and 319% outdoors, highlighting the strong influence of firecracker combustion. Potassium (K⁺), a marker of pyrotechnic activity, also surged during Diwali by ~184% indoors and ~68% outdoors compared to PrD. During Di, sulfate dominated the water-soluble anions. The ammonium to sulfate+nitrate ratio dropped below 1 during Diwali, suggesting enhanced aerosol acidity due to incomplete neutralization of acidic species. HR-ToF-AMS analysis revealed the steeper slope between fC\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e3\u003c/sub\u003eO\u003csup\u003e+\u003c/sup\u003e and fCO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e [ C\u003csub\u003e2\u003c/sub\u003eH\u003csub\u003e3\u003c/sub\u003eO\u003csup\u003e+\u003c/sup\u003e(m/z=43) , and CO\u003csub\u003e2\u003c/sub\u003e\u003csup\u003e+\u003c/sup\u003e (m/z=44) to Organic Aerosol ratio] during Di time, indicating rapid decarboxylation or enhanced fragmentation. Volume-normalized oxidative potential (OP\u003csup\u003eDTTv\u003c/sup\u003e) reached 8.46 (±2.25) and 8.98 (±2.52) nmol min\u003csup\u003e-1\u003c/sup\u003em\u003csup\u003e-3\u003c/sup\u003e indoor, and outdoor, respectively, reflecting a ~270% ,and ~216% \u0026nbsp;enhancement relative to PrD. These results demonstrate that short-term pyrotechnic activities during Diwali substantially altered aerosol chemistry, carbonaceous composition, and oxidative potential, even within a relatively low-traffic academic–residential environment. The average number of passively smoked cigarettes (PSC) reached more than 20 for cardiovascular mortality during the Di period.\u003c/p\u003e","manuscriptTitle":"Impacts of Diwali fireworks on aerosol levels, composition, chemistry, and toxicity: Insights from a combined indoor-outdoor study","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2026-01-12 03:26:19","doi":"10.21203/rs.3.rs-8473668/v1","editorialEvents":[{"type":"communityComments","content":0}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"researchsquare","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":true,"externalIdentity":"","sideBox":"","snPcode":"","submissionUrl":"/submission","title":"Research Square","twitterHandle":"researchsquare","acdcEnabled":true,"dfaEnabled":false,"editorialSystem":"","reportingPortfolio":"","inReviewEnabled":false,"inReviewRevisionsEnabled":true}}],"origin":"","ownerIdentity":"28ae5d1c-05a4-4801-b0fc-81d248245a23","owner":[],"postedDate":"January 12th, 2026","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"posted","subjectAreas":[],"tags":[],"updatedAt":"2026-02-16T20:39:09+00:00","versionOfRecord":[],"versionCreatedAt":"2026-01-12 03:26:19","video":"","vorDoi":"","vorDoiUrl":"","workflowStages":[]},"version":"v1","identity":"rs-8473668","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-8473668","identity":"rs-8473668","version":["v1"]},"buildId":"XKTyCvWXoU3ODBz1xrDgd","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}