Impact of Air Pollution on Age and Gender Related Increase in Cough Reflex Sensitivity of Healthy Children in Slovakia.

Silvia Demoulin-Alexikova,Jan Hanacek,Jana Plevkova,Lenka Mazurova,Milos Tatar,Mikulas Alexik,Tomas Zatko

doi:10.3389/fphys.2016.00054

Abstract

Background: Numerous studies show higher cough reflex sensitivity (CRS) and cough outcomes in children compared to adults and in females compared to males. Despite close link that exists between cough and environment the potential influence of environmental air pollution on age- and gender -related differences in cough has not been studied yet.Purpose: The purpose of our study was to analyse whether the effects of exposure to environmental tobacco smoke (ETS) from parental smoking and PM10 from living in urban area are implied in age- and gender-related differences in cough outcomes of healthy, non-asthmatic children. Assessment of CRS using capsaicin and incidence of dry and wet cough was performed in 290 children (mean age 13.3 ± 2.6 years (138 females/152 males).Results: CRS was significantly higher in girls exposed to ETS [22.3 μmol/l (9.8–50.2 μmol/l)] compared to not exposed girls [79.9 μmol/l (56.4–112.2 μmol/l), p = 0.02] as well as compared to exposed boys [121.4 μmol/l (58.2–253.1 μmol/l), p = 0.01]. Incidence of dry cough lasting more than 3 weeks was significantly higher in exposed compared to not exposed girls. CRS was significantly higher in school-aged girls living in urban area [22.0 μmol/l (10.6–45.6 μmol/l)] compared to school-aged girls living in rural area [215.9 μmol/l (87.3–533.4 μmol/l); p = 0.003], as well as compared to teenage girls living in urban area [108.8 μmol/l (68.7–172.9 μmol/l); p = 0.007]. No CRS differences were found between urban and rural boys when controlled for age group. No CRS differences were found between school-aged and teenage boys when controlled for living area.Conclusions: Our results have shown that the effect of ETS on CRS was gender specific, linked to female gender and the effect of PM10 on CRS was both gender and age specific, related to female gender and school-age. We suggest that age and gender related differences in incidence of cough and CRS might be, at least partially, ascribed to the effect of environmental pollutants. The role of age and gender in the effect of air pollution on cough strongly suggest some interplay of development with biological and behavioral factors.

Highlights

Cough is the most frequent respiratory symptom that leads adults and children to use over-the-counter medications or seek medical help
Despite close link that exists between cough and environment, the potential influence of environmental air pollution on increased capsaicin cough sensitivity and higher cough outcomes in children compared to adults and in females compared to males has not been studied yet
The aim of our study was to analyse whether the effects of indoor air pollution related to environmental tobacco smoke (ETS) and outdoor air pollution related to living in urban area are implied in age- and genderrelated differences in cough outcomes of otherwise healthy children

Summary

Introduction

Cough is the most frequent respiratory symptom that leads adults and children to use over-the-counter medications or seek medical help. Cough starts to appear after 2nd month of life when child looses the protection of maternally acquired antibodies and becomes susceptible to upper respiratory infections (Thach, 2001, 2007). Later, it becomes the most frequent respiratory symptom in toddlers and preschoolers. Cough reflex sensitivity (CRS) to capsaicin in young children decreases with age (Chang et al, 1996, 1997a,b) and toward adulthood by gender (Chang et al, 1997c,d; Kastelik et al, 2002; Varechova et al, 2008). Assessment of CRS using capsaicin and incidence of dry and wet cough was performed in 290 children (mean age 13.3 ± 2.6 years (138 females/152 males)

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