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Background
Throughout the second half of 2019, the use of tear gas by the Hong Kong Police Force on protesting crowds has yielded much debate. Previous international studies have recognised the significant and pervasive health effects of tear gas.
Methods
Researchers at the Citizens’ Press Conference, a citizen-initiated broadcast platform, collected 17766 valid responses from their large-scale online survey on the participants’ roles in the Hong Kong pro-democracy movement, the locations of their homes and workplaces, and any adverse symptoms suffered from tear gas exposure.
Results
Severe medical symptoms induced directly by tear gas, some of which unseen in previous studies elsewhere, have been recorded. Results from our structural equation modelling analysis show significant associations between the respondents’ symptom scores and their roles in protests, the number of geographical districts in which they have come into direct contact with tear gas, a gender bias, and the amount and types of protective gear used (albeit a measure of their involvement in street protests and on the frontline). The respondents’ roles in protests and the gender bias are also significantly correlated with their symptom scores for indirect exposures to tear gas, i.e. when they are not actively participating in protests.
Conclusions
Our findings suggest that adverse medical symptoms from tear gas exposure are pervasive across both protesting and non-protesting demographics, and specific susceptible subpopulations of note have been identified. Inter-district spread of irritants originating from areas where episodes of tear gas overuse by the police have occurred has also been denoted in our results. Future modelling studies of the geographical flow of tear gas chemicals and subsequent analyses on the health risk this brings to residents should be pursued for a fuller understanding of the whole picture of the adverse effects of tear gas on the health of the Hong Kong population.