{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,7,14]],"date-time":"2026-07-14T13:00:03Z","timestamp":1784034003501,"version":"3.55.0"},"reference-count":38,"publisher":"BMJ","issue":"11","license":[{"start":{"date-parts":[[2025,4,24]],"date-time":"2025-04-24T00:00:00Z","timestamp":1745452800000},"content-version":"unspecified","delay-in-days":0,"URL":"http:\/\/creativecommons.org\/licenses\/by-nc\/4.0\/"}],"funder":[{"name":"Childrens Lung Foundation","award":["No award\/grant number"],"award-info":[{"award-number":["No award\/grant number"]}]},{"DOI":"10.13039\/501100009708","name":"Novo Nordisk Foundation","doi-asserted-by":"crossref","award":["NNF17OC0027812"],"award-info":[{"award-number":["NNF17OC0027812"]}],"id":[{"id":"10.13039\/501100009708","id-type":"DOI","asserted-by":"crossref"}]}],"content-domain":{"domain":["bmj.com"],"crossmark-restriction":true},"short-container-title":["Thorax"],"accepted":{"date-parts":[[2025,3,31]]},"published-print":{"date-parts":[[2025,11]]},"abstract":"<jats:sec>\n                    <jats:title>Background<\/jats:title>\n                    <jats:p>Ultrafine particles (UFP; &lt;0.1\u2009\u00b5m in diameter) are not regulated or commonly monitored but may be harmful to human health, particularly for children. In this study, we aimed to examine the association between short-term exposure to UFP and asthma hospital admissions in children.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Methods<\/jats:title>\n                    <jats:p>Daily UFP concentrations (2002\u20132018) were monitored at an urban background station in Copenhagen, Denmark. Asthma hospital admissions, demographic and socioeconomic information of children (0\u201318 years) were obtained from registries. A case-crossover design was applied to estimate the association between hospital admissions and up to 6-day UFP exposure windows for all children, and stratified by age, sex, family income, mother\u2019s education, prior asthma or prior respiratory infection.<\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Results<\/jats:title>\n                    <jats:p>\n                      We observed 15\u2009903 asthma hospital admissions in total. An IQR increase in UFP was significantly associated with asthma hospital admissions, strongest at 2-day exposure windows (risk ratio (RR): 1.17 (95% CI: 1.09, 1.25)). These associations remained unchanged when adjusting for particulate matter &lt;2.5\u2009\u00b5m in diameter (PM\n                      <jats:sub>2.5<\/jats:sub>\n                      ) or nitrogen dioxide (NO\n                      <jats:sub>2<\/jats:sub>\n                      ), for which we also detected significant positive associations. Associations with UFP were stronger for school-aged children (5\u201314 years: RR: 1.26 (95% CI: 1.15, 1.38)) than for children younger than 5 years (1.01 (95% CI: 0.93, 1.10)).\n                    <\/jats:p>\n                  <\/jats:sec>\n                  <jats:sec>\n                    <jats:title>Conclusions<\/jats:title>\n                    <jats:p>\n                      In this large study in a low-exposure setting, we find that short-term exposure to UFP can trigger asthma hospital admissions in children, independently of associations with PM\n                      <jats:sub>2.5<\/jats:sub>\n                      or NO\n                      <jats:sub>2<\/jats:sub>\n                      . This study adds evidence calling for the regulation and improvement of UFP exposure assessment to protect children\u2019s health in urban areas.\n                    <\/jats:p>\n                  <\/jats:sec>","DOI":"10.1136\/thorax-2024-222465","type":"journal-article","created":{"date-parts":[[2025,4,24]],"date-time":"2025-04-24T13:20:27Z","timestamp":1745500827000},"page":"796-802","update-policy":"https:\/\/doi.org\/10.1136\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":1,"title":["Short-term exposure to ultrafine particles and asthma hospital admissions in children in Copenhagen, Denmark"],"prefix":"10.1136","volume":"80","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5743-5564","authenticated-orcid":false,"given":"Marie","family":"Bergmann","sequence":"first","affiliation":[{"name":"Department of Public Health, University of Copenhagen, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zorana J","family":"Andersen","sequence":"additional","affiliation":[{"name":"Department of Public Health, University of Copenhagen, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Andreas","family":"Massling","sequence":"additional","affiliation":[{"name":"Department of Environmental Science, Aarhus University, Aarhus, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Steffen","family":"Loft","sequence":"additional","affiliation":[{"name":"Department of Public Health, University of Copenhagen, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Thomas","family":"Cole-Hunter","sequence":"additional","affiliation":[{"name":"Department of Public Health, University of Copenhagen, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Claus","family":"Nordstr\u00f8m","sequence":"additional","affiliation":[{"name":"Department of Environmental Science, Aarhus University, Aarhus, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"St\u00e9phane","family":"Tuffier","sequence":"additional","affiliation":[{"name":"Department of Public Health, University of Copenhagen, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0779-6908","authenticated-orcid":false,"given":"Jiawei","family":"Zhang","sequence":"additional","affiliation":[{"name":"Department of Public Health, University of Copenhagen, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Youn-Hee","family":"Lim","sequence":"additional","affiliation":[{"name":"Department of Public Health, University of Copenhagen, Copenhagen, Denmark"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[2025,4,24]]},"reference":[{"key":"2026071304500824000_80.11.796.1","doi-asserted-by":"publisher","DOI":"10.1038\/s12276-020-0403-3"},{"key":"2026071304500824000_80.11.796.2","doi-asserted-by":"publisher","DOI":"10.1007\/s00038-019-01202-7"},{"key":"2026071304500824000_80.11.796.3","unstructured":"Morawska L , Wierzbicka A , Buonanno G , et al . 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