Short-term impact of exposure to ambient air volatile organic compounds on daily clinic visits for urticaria in Kaohsiung, Taiwan.

BACKGROUND

Air volatile organic compounds (VOCs) cause allergic reaction mainly via the respiratory tract or skin.

OBJECTIVE

This study aimed to investigate the association between daily visits by patients with urticaria and short-term changes in exposure to ambient air VOCs.

METHODS

The dependent variable was information from patients with urticaria at a medical center in Kaohsiung, Taiwan, from 2014/01/01 to 2018/07/31. The multivariable model included one-day average 75th percentile values of air VOCs and meteorologic data retrieved from Taiwan Air Quality Monitoring Network database, and was analyzed using a case-crossover study design and conditional logistic regression.

RESULTS

Total daily clinic visits for urticaria were significantly positively associated with higher levels of 4 VOCs (ethylbenzene, toluene, m-/p-xylene, and o-xylene (adjusted odds ratio (AOR: 1.03-1.28)) on the visit days, and 10 VOC levels on the fourth lag day (benzene, ethylbenzene, toluene, m-/p-xylene, o-xylene, 1,3,5-trimethylbenzene, n-hexane, methylcyclohexane, cyclohexane, and ethylene (AOR: 1.02-3.02)). Analyses of age and gender subgroups revealed that men showed resistance on the visit day, and women, older, and younger patients were more vulnerable. Men were influenced by higher benzene levels (AOR = 1.24) on the fourth lag day. Higher values of more than 6 VOCs on the fourth lag day significantly affected women, younger and older patients (AOR: 1.04-6.5). The most notable VOCs were methylcyclohexane (women AOR = 3.28, younger AOR = 3.82) and 1,3,5-trimethylbenzene (women AOR = 2.77, older AOR = 6.5) on the fourth lag day, which had the lowest concentrations but highest influence.

CONCLUSION

The concentration of certain air VOCs significantly affected daily visits for urticaria.