Demographic characteristics
Time of admission (year) 2018 2019 2020 2021 Total 2018-2021 Peak 2021
Number of admissions 32 41 36 59 168 38
Girls 8 (25%) 16 (39%) 14 (38.9%) 27 (45.8%) 65 (38.7%) 18 (47.4%)
Age in years, mean ± SD 7.0 ± 3.6 7.1 ± 3.7 7.9 ± 3.6 7.4 ± 3.6 7.4 ± 3.6 7.0 ± 3.5
Divorced parents 12 (37.5%) 12 (29.3%) 8 (22.2%) 17 (28.8%) 49 (29.2%) 12 (31.6%)
Living with a single parent 8 (25%) 8 (19.5%) 1 (2.8%) 8 (13.6%) 25 (14.9%) 4 (10.5%)
Environmental characteristics Environmental characteristics Environmental characteristics Environmental characteristics Environmental characteristics Environmental characteristics Environmental characteristics
Tobacco smoke exposure (TSE) 12 (37.5%) 14 (34.1%) 12 (33.3%) 15 (25.%) 53 (31.5%) 8 (21.1%)
Ambient PM2.5 concentration (micrograms per cubic meter of air), median (25th-75th percentiles) 10.4 (6.5-17.5) 7.4 (4.4-12.63) 7.6 (4.7-11.7) 9.5 (6.4-13.8) 8.6 (5.5-13.9) 9.9 (6.9-14)
Pollen (grains per cubic meter of air), median (25th-75th percentiles) 7 (1-28) 14.5 (2-60.7) 7 (1-22) 4 (1-25.7) 7 (1-30.5) 1 (1-8.5)
Clinical characteristics Clinical characteristics Clinical characteristics Clinical characteristics Clinical characteristics Clinical characteristics Clinical characteristics
Clinical diagnosis of viral infection† 28 (87.5%) 22 (53.7%) 25 (69.4%) 43 (72.9%) 118 (70.2%) 29 (76.3%)
Conducting virology laboratory tests‡ 12 (37.5%) 18 (43.9%) 30 (83.3%) 41 (62.5%) 101 (60.1%) 24 (63.2%)
Allergy history 18 (56.3%) 19 (46.3%) 19 (52.8%) 31 (52.5%) 90 (53.6%) 18 (47.4%)
Previously diagnosed with asthma 19 (59.4%) 21 (51.2%) 15 (41.7%) 21 (35.6%) 76 (45.2%) 13 (34.2%)
Days between symptom onset and admission, median (25th-75th percentiles) 3 (1-7) 2 (1-3.375) 2 (1-4) 3 (2-6.25) 2 (1-5) 2.5 (2-5)
Duration of hospitalization in days, median (25th-75th percentiles) 2 (2-3) 2 (1-3.5) 2 (2-3) 2 (2-3) 2 (1-3) 2 (2-3.25)
Severe acute asthma triggers*5 Severe acute asthma triggers*5 Severe acute asthma triggers*5 Severe acute asthma triggers*5 Severe acute asthma triggers*5 Severe acute asthma triggers*5 Severe acute asthma triggers*5
URTI 27 (84.4%) 27 (65.9%) 30 (83.3%) 31 (52.5%) 115 (68.5%) 19 (50%)
Pneumonia 0 (0%) 7 (17.1%) 1 (2.8%) 10 (16.9%) 18 (10.7%) 8 (21.1%)
Allergens (e.g. pollen, dust mite, chemicals) 6 (18.8%) 5 (12.2%) 9 (25%) 8 (13.6%) 28 (16.7%) 3 (7.9%)
Dogs/cats 0 (0%) 1 (2.4%) 0 (0%) 1 (1.7%) 2 (1.2%) 0 (0%)
(Tobacco) smoke 0 (0%) 4 (9.8%) 1 (2.8%) 0 (0%) 5 (3%) 0 (0%)
Cold and/ or dry air 0 (0%) 0 (0%) 1 (2.8%) 2 (3.4%) 3 (1.8%) 1 (2.6%)
Physical exercise 0 (0%) 1 (2.4%) 0 (0%) 2 (3.4%) 3 (1.8%) 1 (2.6%)
Gastroesophageal reflux 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%) 0 (0%)
No trigger 1 (3.1%) 7 (17.1%) 2 (5.6%) 8 (13.6%) 18 (10.7%) 7 (18.4%)
Abbreviations: PM2.5 = fine particulate matter; URTI = upper respiratory tract infection. Footnotes: † As per physician diagnosis. ‡ There were two types of viral test kit used; a simple one (Influenza A and B, SARS-CoV-2 and RSV) and a complete one (twelve respiratory viruses) § As recorded in admission notes. More than one trigger can be recorded, resulting in percentages adding to more than 100% ¶ Peak 2021 was the time period from August to November 2021 Abbreviations: PM2.5 = fine particulate matter; URTI = upper respiratory tract infection. Footnotes: † As per physician diagnosis. ‡ There were two types of viral test kit used; a simple one (Influenza A and B, SARS-CoV-2 and RSV) and a complete one (twelve respiratory viruses) § As recorded in admission notes. More than one trigger can be recorded, resulting in percentages adding to more than 100% ¶ Peak 2021 was the time period from August to November 2021 Abbreviations: PM2.5 = fine particulate matter; URTI = upper respiratory tract infection. Footnotes: † As per physician diagnosis. ‡ There were two types of viral test kit used; a simple one (Influenza A and B, SARS-CoV-2 and RSV) and a complete one (twelve respiratory viruses) § As recorded in admission notes. More than one trigger can be recorded, resulting in percentages adding to more than 100% ¶ Peak 2021 was the time period from August to November 2021 Abbreviations: PM2.5 = fine particulate matter; URTI = upper respiratory tract infection. Footnotes: † As per physician diagnosis. ‡ There were two types of viral test kit used; a simple one (Influenza A and B, SARS-CoV-2 and RSV) and a complete one (twelve respiratory viruses) § As recorded in admission notes. More than one trigger can be recorded, resulting in percentages adding to more than 100% ¶ Peak 2021 was the time period from August to November 2021 Abbreviations: PM2.5 = fine particulate matter; URTI = upper respiratory tract infection. Footnotes: † As per physician diagnosis. ‡ There were two types of viral test kit used; a simple one (Influenza A and B, SARS-CoV-2 and RSV) and a complete one (twelve respiratory viruses) § As recorded in admission notes. More than one trigger can be recorded, resulting in percentages adding to more than 100% ¶ Peak 2021 was the time period from August to November 2021 Abbreviations: PM2.5 = fine particulate matter; URTI = upper respiratory tract infection. Footnotes: † As per physician diagnosis. ‡ There were two types of viral test kit used; a simple one (Influenza A and B, SARS-CoV-2 and RSV) and a complete one (twelve respiratory viruses) § As recorded in admission notes. More than one trigger can be recorded, resulting in percentages adding to more than 100% ¶ Peak 2021 was the time period from August to November 2021 Abbreviations: PM2.5 = fine particulate matter; URTI = upper respiratory tract infection. Footnotes: † As per physician diagnosis. ‡ There were two types of viral test kit used; a simple one (Influenza A and B, SARS-CoV-2 and RSV) and a complete one (twelve respiratory viruses) § As recorded in admission notes. More than one trigger can be recorded, resulting in percentages adding to more than 100% ¶ Peak 2021 was the time period from August to November 2021