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Comparison of total suspended particulate concentration-response relationships for respiratory symptoms between
Guowei Pan1, Jun Kagawa, Shujuan Zhang
1Dept. of Environmental Epidemiology, Liaoning Provincial Center for Disease Control and Prevention, Shenyang, PR China. panpgw@yahoo.com.cn
Insights
Children
Area of Science:
- Environmental Health
- Pediatric Respiratory Medicine
- Epidemiology
Background:
- Limited research exists on concentration-response (C-R) relationships between particulate matter (PM) and pediatric respiratory illness.
- Understanding how children's susceptibility influences these C-R relationships is crucial for public health.
- Existing studies often overlook variations in C-R curve shapes based on susceptibility.
Purpose of the Study:
- To investigate the concentration-response (C-R) relationships between total suspended particulate (TSP) matter and respiratory symptoms in children.
- To compare the shapes of C-R curves for bronchitis and asthma symptoms between children with differing susceptibility levels.
- To identify how susceptibility status modifies the association between TSP exposure and respiratory health outcomes.
Main Methods:
- Utilized restricted cubic spline (RCS) functions to model C-R relationships between TSP and respiratory symptom prevalence.
- Analyzed data from 11,860 children across six cities in Liaoning province, China.
- Controlled for confounding factors including sulfur dioxide (SO2) and nitrogen dioxide (NO2) levels.
Main Results:
- Susceptible children showed a 2- to 3-fold higher prevalence of all four respiratory symptoms across the observed TSP range (188-689 μg/m³).
- Distinct C-R curve shapes were observed: 'S'-shaped for bronchitis and 'U'-shaped for asthma symptoms, varying by susceptibility.
- A significant linear association between TSP and current asthma was found only in susceptible children exposed to high TSP levels.
Conclusions:
- The shapes and characteristics of TSP-morbidity C-R curves are significantly influenced by respiratory symptom type, child susceptibility, and TSP concentration.
- Susceptible children face a disproportionately higher risk of respiratory symptoms even at moderate TSP levels.
- Further research is needed to characterize these C-R relationships in diverse global settings with varying PM levels.
Abstract:
Few studies have explored concentration-response (C-R) relationships between levels of particulate matter (PM) and respiratory morbidity in terms of the susceptibility of children to respiratory diseases. We sought to determine whether the shapes of C-R curves for comparing total suspended particle (TSP) concentration versus the adjusted prevalence of bronchitis (persistent cough or phlegm) and asthma (current wheeze or asthma) symptoms between children with a different susceptibility status. We used the restricted cubic spline (RCS) function to characterize the C-R relationships between TSP and the adjusted prevalence rates of four respiratory symptoms, after controlling for possible confounding by SO(2) and NO(2) levels, in 11,860 children selected from 18 districts of six cities in Liaoning province. Susceptible children exhibited a 2- to 3-fold elevation in the prevalence of all four respiratory symptoms across the entire TSP range (188-689μg/m(3)). Significant differences in the shapes of C-R curves were evident in children with symptoms of bronchitis (ballistic "S"-shaped curves) and asthma (flattened "U"-shaped curves), as well as between the low and high TSP ranges of such curves, when children were grouped by susceptibility status. A significant linear association between TSP levels and current asthma prevalence was found only among susceptible children exposed to high levels of TSP. The shapes and properties of the TSP-morbidity C-R curves differed significantly by type of respiratory symptom, susceptibility status, and TSP range. More work is required to characterize CR relationships in terms of susceptibility status in countries with different PM levels.