Multi-Factor Analysis of Single-Center Asthma Control in Xiamen, China

Causal relationship between outdoor atmospheric quality and pediatric asthma visits in hangzhou

Many air pollutants and climate variables have proven to be significantly associated with pediatric asthma and have worsened asthma symptoms. However, their exact causal effects remain unclear. We explored the causality between air pollutants, climate, and daily pediatric asthma patient visits with a short-term lag effect. Based on eight years of daily environmental data and daily pediatric asthma patient visits, Spearman correlation analysis was used to select the air pollutants and climate variables that correlated with daily pediatric asthma patient visits at any time (with a lag of 1-6 days). We regarded these environmental variables as treatments and built multiple- and single-treatment causal inference models using the Dowhy library (a Python library for causal inference by graphing the model, quantitatively evaluating causal effects, and validating the causal assumptions) to estimate the quantitative causal effect between these correlated variables and daily pediatric asthma patient visits in lag time. The multiple-treatment causal inference model was a model with 8 treatments (Visibility, Precipitation, PM₁₀, PM_2.5, SO₂, NO₂, AQI and CO), 1 outcome (daily pediatric asthma patients visits), and 5 confounders (Humidity, Temperature, Sea level pressure, wind speed and unobserved confounders "U"). Single-treatment causal inference models were 8 models, and each model has 1 treatment, 1 outcome and 12 confounders. Spearman correlation analysis showed that precipitation, wind speed, visibility, air quality index, PM_2.5, PM₁₀, SO₂, NO₂, and CO were significantly associated variables at all times (p < 0.05). The multiple-treatment model showed that pooled treatments had significant causality for the short-term lag (lag1-lag6; p < 0.05). Causality was mainly due to SO₂. In the single-treatment models, visibility, SO₂, NO₂, and CO exhibited significant causal effects at any one time (p < 0.05). SO₂ and CO exhibited stronger positive causal effects. The causal effect of SO₂ reached its maxima (causal effect = 11.41, p < 0.05) at lag5. The greatest causal effect of CO appeared at lag3 (causal effect = 10.67, p < 0.05). During the eight year-period, the improvements in SO₂, CO, and NO₂ in Hangzhou were estimated to reduce asthma visits by 8478.03, 3131.08, and 1341.39 per year, respectively. SO₂, NO₂, CO, and visibility exhibited causal effects on daily pediatric asthma patient visits; SO₂ was the most crucial causative variable with a relatively higher causal effect, followed by CO. Improvements in atmospheric quality in the Hangzhou area have effectively reduced the incidence of asthma.

Association between Asthma Control and Exposure to Greenness and Other Outdoor and Indoor Environmental Factors: A Longitudinal Study on a Cohort of Asthmatic Children

Achieving and maintaining asthma control (AC) is the main goal of asthma management. Indoor and outdoor environmental factors may play an important role on AC. The aim of this longitudinal study was to evaluate the association between AC and exposure to greenness and other outdoor or indoor environmental factors in a cohort of asthmatic children. This study involved 179 asthmatic children (5-16 years). Parents were interviewed through a modified version of the SIDRIA questionnaire. AC was assessed at each visit. Exposure to greenness was measured using the normalized difference vegetation index (NDVI). A logistic regression model was applied for assessing risk factors for uncontrolled asthma (UA). Low NDVI exposure was a risk factor for UA (OR: 2.662, 95% CI (1.043-6.799)); children exposed to passive smoke during pregnancy had a higher risk of UA than those non-exposed to passive smoke during pregnancy (OR: 3.816, 95% CI (1.114-13.064)); and a unit increase in the crowding index was associated with an increased risk of UA (OR: 3.376, 95% CI (1.294-8.808)). In conclusion, the current study provided a comprehensive assessment of urban-related environmental exposures on asthma control in children, using multiple indicators of greenness and other outdoor or indoor environmental factors.

Ozone Exposure and Asthma Attack in Children

BACKGROUND

Increasing evidence indicated that ozone (O₃) exposure could trigger asthma attacks in children. However, the effect of O₃ at low concentrations is uncertain.

PURPOSE

This study aimed to explore the effects of O₃ exposure at low concentrations on asthma attacks in children.

METHODS

A total of 3,475 children with asthma attacks from the First Affiliated Hospital of Xiamen University were available for the analyses. Air pollution data and meteorological data in Xiamen during 2016-2019 were also collected. A case-crossover design and conditional logistic regression models were conducted to evaluate the association between asthma attacks and outdoor air pollution with lag structures (from lag 0 to lag 6) in both single and multi-pollutant models. Furthermore, we estimated the influence of various levels of O₃ exposure on an asthma attack in three groups categorized by maximum daily 8-h sliding average ozone (O₃-8 h) (O₃-8 h ≥ 100 μg/m³, O₃-8 h: 80-99 μg/m³, O₃-8 h < 80 μg/m³).

RESULTS

For both single-pollutant models and multi-pollutant models, when O₃-8 h was higher than 80 μg/m³, O₃ exposure was increased the risk of acute asthma attacks on each day of lag. The effect of O₃ on children with asthma was significant when O₃ concentration was higher than 100 μg/m³.

CONCLUSION

O₃ concentration above 80 μg/m³ contributed to an increased risk of asthma attacks in children.

Association between indoor formaldehyde exposure and asthma: A systematic review and meta-analysis of observational studies

About 339 million people worldwide are suffering from asthma. We aimed to investigate whether exposure to formaldehyde (FA) is associated with asthma, which could provide clues for preventive and mitigation actions. This article provides a systematic review and meta-analysis of observational studies to assess the association between indoor FA exposure and the risk of asthma in children and adults. An electronic search of PubMed, Embase, and Web of Science was performed to collect all relevant studies published before January 1, 2020, and a total of 13 papers were included in this meta-analysis. A random-effect model was conducted to calculate the pooled odds ratio (OR) between FA exposure and asthma. We found that each 10 µg/m³ increase in FA exposure was significantly associated with a 10% increase in the risk of asthma in children (OR = 1.10, 95% confidence interval = 1.00-1.21). We sorted the FA concentrations reported in the selected articles and categorized exposure variables into low (FA ≤ 22.5 µg/m³ ) and high exposure (FA > 22.5 µg/m³ ) according to the median concentration of FA. In the high-exposure adult group, FA exposure may also be associated with an increased risk of asthma (OR = 1.81, 95% CI = 1.18-2.78).