Hourly air pollution exposure and the onset of symptomatic arrhythmia: an individual-level case–crossover study in 322 Chinese cities

Air pollution is a com- death.1–3 The Global Burden of Disease study estimated a preva- plex mixture of particulates and gases that varies by time and lence of around 59.7 million cases of atrial fibrillation and atrial flut- location.7,8 Common air pollutants tracked by the World Health ter globally in 2019, and the disability-adjusted life years related to Organization (WHO) and government agenc. [...] We in previous studies.42–44 selected the corresponding control periods for each patient to be in We conducted several sensitivity analyses to determine the the same hour, day of week, month and year to control for time robustness of the associations between air pollutants and trends such as circadian rhythms and seasonality.38 For example, if a arrhythmia onset. [...] Given the nature of our database and study design, the The existing evidence on the association of gaseous pollutants observed triggering effect of air pollution could be the result of with arrhythmia is also inconsistent.15,55–60 Several studies have an acute worsening or a recurrent episode of a pre-existing reported no association,14,54,60 but we found NO2 had the strongest arrhythmia (includin. [...] The associations are presented as percentage change in the odds of the outcome in comparison to the odds at the median concentration over a lag period of 0–24 hours. [...] Our study adds to evidence of uncertain.14,41,74 We found evidence on lag patterns, which indi- adverse cardiovascular effects of air pollution, highlighting the cated that air pollution was associated with the onset of symp- importance of further reducing exposure to air pollution and of tomatic arrhythmia within the first hours of exposure.