Assessing health risks of exposure to Asian dust (soil dust) among healthy individuals and allergic rhinitis patients in Japan

INTRODUCTION:    The health effects of Asian dust and air pollution have been reported, but the possibility of exacerbation of or synergy with allergic rhinitis (including pollinosis) remains unclear. Therefore, we assessed the adverse health effect from exposure to Asian dust among healthy individuals and allergic rhinitis patients.

METHODS:    The survey participants were Ninety-six residents (50 men; 46 women; 26 with allergic rhinitis) in Yonago City, Tottori. The participants completed self-administered questionnaires every day from February to May 2009 and from February to April 2010. In the questionnaire they subjectively evaluated nose, eye, respiratory, and skin symptoms using a visual analog scale (0–5) on each day. Concentrations of mineral and non-mineral dust were estimated by the light detection and ranging with a polarization analyzer in Matsue. We considered NO2, SO2, Ox, pollen, temperature, atmospheric pressure and humidity as possible confounders. Generalized estimating equation is used for data analysis.

RESULTS:     A statistically significant association was shown between the total score of each symptom and heavy Asian dust event（top 5% of daily average）. The odds ratio (OR) of the heavy Asian dust event to any symptom for healthy subjects was 1.2 (95% confidence interval, 1.0–1.5) and for allergic rhinitis patients was 2.4 (1.4–4.2). An environmental factor particularly relevant to the health risks of Asian dust was pollen. In single-pollutant model, the OR of heavy Asian dust event to nasal symptom was 1.37 (1.19–1.58), which was attenuated by pollen, but remained significant (1.18, 95%CI:1.04–1.34).

CONCLUSIONS:     Even healthy subjects demonstrated elevated symptom score at heavy Asian dust event. Further, subjects with allergic rhinitis showed greater risk of nasal symptom aggravation than healthy subjects.