Different Impacts of Traffic-Related Air Pollution on Early-Onset and Late-Onset Asthma

Abstract

Background

Early-onset asthma (EOA) and late-onset asthma (LOA) are two distinct phenotypes. Air pollution has been associated with an increase in poorer asthma outcomes. The objective of this study was to examine the effects of traffic-related air pollution (TRAP) on asthma outcomes in EOA and LOA patients.

Methods

A cross-sectional study was conducted on 675 asthma patients (LOA: 415) recruited from a major medical center in Taiwan. The land-use regression (LUR) model was used to estimate the level of exposure to PM₁₀, PM_2.5, NO₂, and O₃ on an individual level. We investigated the association between TRAP and asthma outcomes in EOA and LOA patients, stratified by allergic sensitization status, using a regression approach.

Results

An increase in PM₁₀ was associated with younger age of onset, increased asthma duration, and decreased lung function in EOA patients (p<0.05). An increase in PM₁₀ was associated with older age of onset, and decreased asthma duration, eosinophil count, and Asthma Control Test (ACT) score in LOA patients. An increase in PM_2.5 was associated with younger age of onset, increased asthma duration, decreased eosinophil count, and lung function in EOA patients (p<0.05). An increase in PM_2.5 was associated with decreased lung function and ACT score in LOA patients. An increase in NO₂ was associated with increased eosinophil count and decreased lung function in EOA patients (p<0.05). An increase in O₃ was associated with decreased lung function in LOA patients (p<0.05). In addition, associations of TRAP with age of onset and eosinophil counts were mainly observed in both EOA and LOA patients with allergic sensitization, and an association with ACT was mainly observed in LOA patients without allergic sensitization.

Conclusion

The impact of TRAP on age of onset, eosinophil count, and lung function in EOA patients, and ACT in LOA patients, was affected by the status of allergic sensitization.

Keywords:

• air pollution
• allergy
• early-onset asthma
• late-onset asthma
• respiratory disease

Abbreviations

ACT, Asthma Control Test; BD, bronchodilator; ECP, eosinophil cationic protein; EOA, early-onset asthma; FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; IgE, immunoglobulin E; LOA, late-onset asthma; NO₂, nitrogen dioxide; O₃, ozone; PM, particulate matter; PM_2.5, particles with an aerodynamic diameter of 2.5 μm or less; PM₁₀, particles with an aerodynamic diameter of 10 μm or less; TRAP, traffic-related air pollution.

Data Sharing Statement

The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.

Ethics Approval and Consent to Participate

The study was performed in accordance with the Declaration of Helsinki and all participants provided written informed consent. The study protocol was approved by the Chang Gung Medical Foundation Institutional Review Board (No. 201900211B0).

Disclosure

The authors declare that they have no competing interests.

Additional information

Funding

This research was funded by a Chang Gung Medical research program grant (CMRPG3L1261).