Meteorological risk factors Location Author Sample size Temperature Relative humidity Thunderstorm Wind speed Rainfall Key measures Results Europe Cardiff and Newport, UK Anderson et al. [14 ] 2000 YES YES Min./max. temperature and total daily rainfall Average daily asthma hospitalization was lower during the summer (4.1, May–September, North America Los Angeles, USA Delamater et al. [16 ] 250, 000 YES YES Max. temperature and relative humidity HAs increased during winter (0.481 per 100,000 admissions) New York, USA Fitzgerald et al. [11 ] 237, 639 YES YES Cold spells lasting three days, where the daily mean temperature was less than the 10th percentile for a given month and region HAs increased in November (mean = 9.6, 95% CI: 5.5% to 13.9%) and April (mean = 5.0, 95% CI: 1.2% to 9.0%) Maryland, USA Soneja et al., 2016 115, 923 YES YES Daily max. temperature and total daily precipitation Extreme heat increased HAs by 3% (OR: 1.03, 95% CI: 1.00 to 1.07) South Asia Bangalore, India Kunikullaya et al., 2017 1768 YES YES YES Max./min./average temp., relative humidity, and total daily rainfall Average daily asthma admission was 4.84 ± 2.91, had seasonal variation and increased during the cold season ( Middle East Kuwait Qasem et al. [20 ] 4353 YES YES YES YES Daily temperature, relative humidity, and total daily rainfall Hospitalization increased during December due to high temperatures (mean = 39.7, East Asia Shanghai, China Zhang et al. [9 ] 15, 678 YES YES YES YES Min./max. and mean temperature, relative humidity, and total daily rainfall RR: 1.20 (95% CI: 1.01 to 1.41) for lower temperatures Hong Kong Lam et al. [19 ] 56, 112 YES YES YES Daily mean temperature and mean relative humidity Cumulative risk of hospitalizations during the hot season was 1.19 (95% CI: 1.06 to 1.34)
