Original article
Systemic allergic disorders
Effect of desert dust exposure on allergic symptoms: A natural experiment in Japan

https://doi.org/10.1016/j.anai.201602002 Get rights and content

Abstract

Background

Desert dust originating from arid and semiarid areas is transported to widespread regions, including Japan. Desert dust particles exert adjuvant effects in animals.

Objective

To examine whether desert dust enhances allergic symptoms in real-life settings and to explore its effect modifiers.

Methods

We conducted an observational study of 3,327 pregnant women during spring and fall in October 2011 to May 2013 in 3 regions in Japan as an adjunct study of the Japan Environment & Children's Study. We acquired participants' daily symptom scores by sending a questionnaire to their mobile phones on high desert-dust days (>0.07/km) and on some randomly selected other days (control days) for each participant.

Results

Pregnant women had an increased risk of allergic symptoms on high desert-dust days (adjusted odds ratio [OR], 1.10; 95% CI, 1.04–1.18). The increased OR was mostly driven by those who showed positive IgE to Japanese cedar pollen when pollen simultaneously dispersed (adjusted OR, 1.25; 95% CI, 1.13–1.38), whereas no clear risk increase was observed in the absence of pollen or for participants with negative IgE to Japanese cedar pollen. The risk elevation was observed from low levels of desert dust in a dose-dependent manner even on control days.

Conclusion

Ambient desert dust level was associated with an increased risk of allergic symptoms in pollen-sensitized pregnant women when pollen was present in the air. The risk increase was dose dependent and was observed from low levels of desert dust. These results support a hypothesis that ambient desert dust particles exert adjuvant effects in human in real-life settings.

Trial Registration

clinicaltrials.gov Identifier: UMIN000010826.

Introduction

Aerosol particles are produced by a variety of natural and anthropogenic processes. Desert dust constitutes approximately 35% of the aerosol mass injected into the troposphere.1 Large quantities of desert dust are transported over the oceans from arid continental regions and are deposited globally.[2], [3], [4] In addition to rock-forming and clay minerals, desert dust particles contain microbial agents, such as bacteria, fungi, and viruses,[2], [4], [5], [6] and anthropogenic atmospheric pollutants are likely absorbed during transport.7 Many toxicologic and controlled human exposure studies have found that particulate matter (PM) exposure alters the immune response to antigens, suggesting that PM may act as an adjuvant,8 which can modify (boost) the effects of allergens. Experiments in animal models have also found that desert dust particles aggravate antigen-induced allergic inflammation.[9], [10] However, few studies have assessed the relevance of these adjuvant effects in real-life settings.
In epidemiologic studies, desert dust events have been linked to health outcomes, such as the exacerbation of asthma or allergic rhinitis, with a subtle to clear risk elevation.[11], [12], [13] It remains unknown why the estimated risk for outcomes, such as the worsening of asthma, varies across studies, with some studies suggesting associations between desert dust and respiratory and allergic outcomes and others not,[14], [15] but a number of effect modifiers might be involved, including differences in the size and composition of particles and the copresence of antigens or other air pollutants.
Asian dust originates from deserts in arid and semiarid areas of the Asian continent, such as the Gobi Desert and Loess Plateau, and is widely dispersed. In the spring and fall, heavy Asian dust blows eastward, sometimes reaching Japan, which is thousands of kilometers away from these arid regions, and gives the air a yellow hue for several days. During the spring, Japanese cedar pollen (JCP), the most common antigen for pollinosis in Japan, is also dispersed, affecting nearly half the population.16
In the present study, we focused on the partial overlap of pollen dispersal and Asian dust seasons to determine whether ambient desert dust exerts adjuvant effects, thereby enhancing the secondary immune response in real-life settings. To this end, we conducted an observational study spanning 4 Asian dust seasons during 2 years as the first part of an adjunct study of a national birth cohort in Japan (Japan Environment & Children's Study [JECS]).[17], [18] The study protocol is registered (UMIN000010826) and has been previously published.17

Section snippets

Design

This study was initiated in 2011 as the first part of an adjunct study of the JECS to examine the effects of desert dust exposure on allergic symptoms in pregnant women and on the development of asthma and other allergic diseases in their children in Kyoto, Toyama, and Tottori.[17], [18] The study protocol was approved by the ethics committees of Kyoto University, University of Toyama, and Tottori University.
On enrollment, baseline information, such as history of asthma and other allergic

Participant Characteristics

A total of 7,829 pregnant women had enrolled at JECS regional centers in Kyoto, Toyama, and Tottori by the end of May 2013. Of these, 4,691 (59.9%) provided consent to participate in the adjunct study, and 4,178 took part in the first part of the study (ie, investigation of the short-term effects of desert dust on pregnant mothers). Among these, 3,327 (79.6%) actually experienced Asian dust seasons (October to November 2011, February to May and October to November in 2012, and February to May

Discussion

In this study, we found that pregnant women are more likely to develop allergic symptoms on Asian dust days compared with non–Asian dust days (adjusted OR, 1.10; 95% CI, 1.04–1.18). The increase in OR was mostly driven by participants with IgE responses to JCP when pollen was present in the air (adjusted OR, 1.25; 95% CI, 1.13–1.38), and no clear increase in risk was observed in the absence of pollen or for those with negative IgE results to JCP. A dose-dependent increase in risk was observed

Acknowledgement

We thank all participants of the study; Toyama Prefectural Environmental Science Research Centre, Higashiosaka City Environmental Department Pollution Control Division, Kyoto Prefectural Government, Department of Culture and the Environment, Lake Biwa Environmental Research Institute, Kyoto City, Environmental Conservation Division of Toyama City Hall, and Air and Water Environment Division for providing air pollution data; Japan Weather Association for pollen data; Japan Meteorological Agency

References (36)

  • Y. Ren et al.

    Aggravation of ovalbumin-induced murine asthma by co-exposure to desert-dust and organic chemicals: an animal model study

    Environ Health

    (2014)
  • US Environmental Protection Agency

    Integrated Science Assessment for Particulate Matter (Final Report)

    (2009)
  • T. Ichinose et al.

    Asian sand dust aggravates allergic rhinitis in guinea pigs induced by Japanese cedar pollen

    Inhal Toxicol

    (2009)
  • Y. Ren et al.

    Enhancement of OVA-induced murine lung eosinophilia by co-exposure to contamination levels of LPS in Asian sand dust and heated dust

    Allergy Asthma Clin Immunol

    (2014)
  • C.C. Chang et al.

    Correlation of Asian dust storm events with daily clinic visits for allergic rhinitis in Taipei, Taiwan

    J Toxicol Environ Health

    (2006)
  • K.T. Kanatani et al.

    Desert dust exposure is associated with increased risk of asthma hospitalization in children

    Am J Respir Crit Care Med

    (2010)
  • J.M. Prospero et al.

    Relationship between African dust carried in the Atlantic trade winds and surges in pediatric asthma attendances in the Caribbean

    Int J Biometeorol

    (2008)
  • M. Hashizume et al.

    Health effects of Asian dust events: a review of the literature [in Japanese]

    Jpn J Hyg

    (2010)

    • Cited by (29)

    View all citing articles on Scopus
    Disclosure: Drs Nakayama and Kanatani disclosed that they started a collaboration study with Duskin, a cleaning company in 2015. Dr Kanatani works as a medical adviser in Bayer Yakuhin. No other disclosures were reported.
    Funding Sources: This work was supported by grant 5C-1152 (2011–2013) from the Environment Research and Technology Development Fund from the Ministry of the Environment of Japan.
    Disclaimer: The findings and conclusions of this article are solely under the responsibility of the authors and do not represent the official views of the Japanese government.
    View full text
    © 2016 American College of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.