Age-dependent effect of ambient ozone on emergency asthma hospitalizations in Hong Kong

[...]ozone was shown to be protective against influenza by reducing influenza disease severity and mitigating acute virus-induced lung injury,3 which may relate to the ozone-primed immunity via the alarmin IL-335,6 against influenza virus infection.7 The inflammatory and antivirus effects of ozone may exert opposite effects on asthma hospitalizations, explaining the differential effects of ozone on asthma in different subpopulations. [...]the reduced risk of asthma hospitalization in children stands in apparent contrast with the elevated risk in adults and the elderly associated with ambient ozone. The differential effects of ozone on asthma reflect the complex roles of ozone in inducing both inflammatory and antiviral responses in different subpopulations.Appendix Distributed lags Asthma in young children (age ≤ 6 y) Asthma in children (age < 18 y) Asthma in adults (age 18-64 y) Asthma in elders (age ≥ 65 y) Lags 0-6 −8.6 (−13.4 to −3.4) −6.6 (−10.7 to −2.3) 8.5 (4.0 to 13.2) 13.2 (8.4 to 18.2) Lags 0-2 −2.8 (−0.9 to 1.7) −2.0 (−4.8 to 0.9) 5.3 (2.5 to 8.2) 7.6 (4.7 to 10.6) Lags 3-6 −6.0 (−8.2 to −3.7) −4.7 (−6.6 to −2.8) 3.1 (1.2 to 5.0) 5.1 (3.2 to 7.1) Lags 7-20 −21.1 (−26.3 to −15.5) −18.7 (−23.3 to −14.0) −7.0 (−11.7 to −2.0) −3.0 (−8.0 to 2.3) Lags 0-20 −27.9 (−34.3 to −20.8) −24.1 (−29.8 to −18.0) 0.9 (−6.1 to 8.4) 9.7 (2.0 to 18.1) Table I Age-stratified percent changes and 95% CIs in asthma emergency hospitalizations with an IQR increase in ozone in different time windows of the lag 0-20 period, based on 2005-2014 data in Hong Kong∗ Variable Mean ± SD Min 25th 50th 75th Max Emergency asthma admissions Age (y) 17.1 ± 5.8 3 13 17 21 43 Young child (≤6 y) 3.9 ± 2.7 0 2 3 5 22 Child (age < 18 y) 6.0 ± 3.7 0 3 5 8 29 Adult (age 18-64 y) 5.6 ± 2.8 0 4 5 7 19 Elder (age ≥65 y) 5.5 ± 2.7 0 4 5 7 18 Sex Female 9.0 ± 3.7 0 6 9 11 22 Male 8.1 ± 3.6 0 6 8 10 26 Season Warm 15.5 ± 5.4 3 12 15 19 40 Cool 18.7 ± 5.8 4 14 18 22 43 Air pollution concentrations (μg/m3) O3 (24-h mean) 36.7 ± 21.7 4.7 18.5 32.1 50.1 134.4 O3 (8-h mean) 47.7 ± 30.0 5.2 24.0 40.5 65.8 194.3 PM2.5 (24-h mean) 34.5 ± 21.0 4.9 17.7 30.0 46.4 174.5 NO2 (24-h mean) 55.7 ± 19.2 13 41.7 52.9 66.7 150.5 Weather conditions Mean temperature (°C) 23.4 ± 5.2 8.4 19.1 24.6 27.9 31.8 Relative humidity (%) 78.4 ± 10.6 29.0 73.0 79.0 86.0 99.0 Table E1 Distribution of emergency hospital admissions for asthma, air pollution concentrations, and meteorological factors in Hong Kong, 2005-2014