Original article
Asthma, lower airway disease
Indoor particulate matter increases asthma morbidity in children with non-atopic and atopic asthma

https://doi.org/10.1016/j.anai.2011.01.015Get rights and content

Background

Compared with atopic asthma, fewer environmental modifications are recommended for non-atopic asthma in children.

Objective

To better understand the role of indoor pollutants in provoking non-atopic asthma, we investigated the effect of in-home particulate matter on asthma symptoms among non-atopic and atopic children living in inner-city Baltimore.

Methods

A cohort of 150 children ages 2 to 6 years with asthma underwent home environmental monitoring for 3-day intervals at baseline, 3, and 6 months. Children were classified as non-atopic if they were skin test negative to a panel of 14 aeroallergens. Caregivers completed questionnaires assessing symptoms and rescue medication use. Longitudinal data analysis included regression models with generalized estimating equations.

Results

Children were primarily African American from lower socioeconomic backgrounds and spent most of their time in the home. Thirty-one percent were non-atopic, and 69% were atopic. Among non-atopic and atopic children, increased in-home fine (PM2.5) and coarse (PM2.5–10) particle concentrations were associated with significant increases in asthma symptoms and rescue medication use ranging from 7% (95% confidence interval [CI], 0–15) to 14% (95% CI, 1–27) per 10 μg/m3 increase in particle concentration after adjustment for confounders.

Conclusions

In-home particles similarly cause increased symptoms of asthma in non-atopic and atopic children. Environmental control strategies that reduce particle concentrations may prove to be an effective means of improving asthma outcomes, especially for non-atopic asthma, for which there are few environmental control practice recommendations.

Introduction

Asthma is influenced by a combination of host susceptibility and environmental factors, including viruses, pollutants, and allergens. Individuals with asthma often have allergic sensitization to allergens, and for these individuals, identification and avoidance of relevant allergens is an established component of asthma management. However, non-atopic asthma contributes significantly to the worldwide and US burden of disease, representing as much as 50% of the world's asthma, although atopic asthma likely predominates in children. Some evidence suggests that non-atopic asthma may confer a worse prognosis compared with atopic asthma1, 2, 3, 4, 5; however, because it is not considered an allergen-driven disease, environmental control recommendations are less well established.

Air pollutants are among the likely candidates of the possible environmental triggers for non-atopic asthma. Previous studies have suggested that air pollutants, such as sulfur dioxide, nitrogen dioxide, carbon monoxide, and benzene, have a stronger effect in non-atopic asthma than atopic asthma.6, 7 Particulate matter (PM) is a common air pollutant that has known detrimental health effects, especially for those with asthma. PM has both outdoor sources, including products of combustion and crustal materials, and indoor sources, including smoking, cooking, and cleaning activities.8, 9 Increases in ambient PM have been associated with greater morbidity in asthma and greater mortality in the general population.10, 11, 12, 13 However, the effect on non-atopic asthma has not been isolated.

Although Americans spend most of their time indoors (>80%), and indoor PM concentrations can exceed those measured outdoors, less is known about the health effects of indoor PM exposure. Previous studies of health effects of indoor PM have linked indoor PM exposure to increases in respiratory symptoms and decreases in pulmonary function but have not evaluated differential health effects of pollutants between atopic and non-atopic asthmatics.11, 14, 15, 16 To better understand the causative mechanism and to inform recommendations for improving the health of those with non-atopic asthma, we first need to provide evidence of the link between exposures and exacerbation of disease. The current study focuses on inner-city preschool-age children with asthma, a group known to have a high burden of disease and to be at risk for increased exposure to environmental pollutants. Using a cohort of well-characterized children with asthma,14, 17 we examined the response to indoor PM exposure in those with non-atopic and atopic asthma.

Section snippets

Study Design

The Johns Hopkins Medical Institutional Review Board approved the study, and all participants provided written informed consent before beginning the study. Children participating in this longitudinal study17 were evaluated at baseline and 3 and 6 months. At each interval, environmental monitoring occurred for 3 consecutive days, and health outcomes were assessed through caregiver report.

Participants

Children were recruited from health systems that provide care to most East Baltimore residents. Inclusion

Participant Characteristics

The 150 preschool children enrolled in this longitudinal cohort study were predominantly African American from lower-income households (Table 1). Of the 133 who completed allergy skin testing, 31% were classified as non-atopic and 69% as atopic. Non-atopic children were slightly younger, with a mean age of 3.9 years, compared with atopic children, who had a mean age of 4.6 years (P = .01). No significant differences were seen between the groups with respect to race, sex, or socioeconomic

Discussion

We found that in-home particle concentrations were associated with asthma morbidity, including symptoms and rescue medication use, among not only atopic but also non-atopic children. Although fewer non-atopic (n = 41) than atopic children (n = 92) were in this inner-city, predominantly African American cohort, we found substantial, statistically significant relationships between in-home PM concentrations and asthma outcomes in this group. The magnitude of the response to PM was similar in

Conclusions

In-home PM concentrations were associated with increased asthma symptoms and the need for rescue medication among both non-atopic and atopic preschool children living in inner-city Baltimore. This finding may be especially important for non-atopic asthmatics, because there are fewer alternative triggers compared with those with atopy. Future studies investigating the impact of interventions to reduce indoor PM and other indoor pollutants may be critical to better understanding the causative

References (49)

  • R. Beasley et al.

    Has the role of atopy in the development of asthma been over-emphasized?

    Pediatr Pulmonol

    (2001)
  • N. Pearce et al.

    How much asthma is really attributable to atopy?

    Thorax

    (1999)
  • P.A. Ostergaard

    Non-IgE-mediated asthma in children

    Acta Paediatr Scand

    (1985)
  • G. Longo et al.

    Non-atopic persistent asthma in children

    Thorax

    (2009)
  • T. Hirsch et al.

    Inner city air pollution and respiratory health and atopy in children

    Eur Respir J

    (1999)
  • L.A. Wallace et al.

    Particle concentrations in inner-city homes of children with asthma: the effect of smoking, cooking, and outdoor pollution

    Environ Health Perspect

    (2003)
  • J.M. Samet et al.

    Fine particulate air pollution and mortality in 20 U.S. cities, 1987–1994

    N Engl J Med

    (2000)
  • R.J. Delfino et al.

    Association of FEV1 in asthmatic children with personal and microenvironmental exposure to airborne particulate matter

    Environ Health Perspect

    (2004)
  • T.F. Mar et al.

    An analysis of the association between respiratory symptoms in subjects with asthma and daily air pollution in Spokane, Washington

    Inhal Toxicol

    (2004)
  • R. McConnell et al.

    Prospective study of air pollution and bronchitic symptoms in children with asthma

    Am J Respir Crit Care Med

    (2003)
  • M.C. McCormack et al.

    In-home particle concentrations and childhood asthma morbidity

    Environ Health Perspect

    (2009)
  • J.Q. Koenig et al.

    Pulmonary effects of indoor- and outdoor-generated particles in children with asthma

    Environ Health Perspect

    (2005)
  • G.B. Diette et al.

    Home indoor pollutant exposures among inner-city children with and without asthma

    Environ Health Perspect

    (2007)
  • B. Brunekreef et al.

    Epidemiological evidence of effects of coarse airborne particles on health

    Eur Respir J

    (2005)
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    Disclosures: The authors have nothing to disclose.

    Funding Sources: Supported by the NIEHS (K23 ES 016819; PO1 ES 09606; P50 ES 015903), NIAID (R01 AI070630) and U.S. EPA (PO1 R-826724), and the Johns Hopkins NIEHS Center in Urban Environmental Health (P30 ES 03819).

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