Interaction Between Bronchiolitis Diagnosed Before 2 Years of Age and Socio-Economic Status for Bronchial Hyperreactivity

OBJECTS: The prevalence of asthma has increased in recent decades globally. The objective of the present study is to elucidate whether hospitalization for bronchiolitis in infancy and low socioeconomic status interact for bronchial hyperreactivity during teenage years. METHOD: We studied 522 children age 13-14 years attending schools in rural and urban areas to investigate the risk factors for bronchial hyperreactivity (BHR), defined as a provocation concentration of methacholine that causes a decrease of 20% (PC20) in forced expiratory volume within 1 second. Clinical examination, skin prick test, spirometry, and methacholine challenge were performed on all study subjects, who provided written consent. We used multivariate logistic regression to investigate the risk factors for BHR, and analyze the interaction between hospitalization for bronchiolitis in infancy and low socioeconomic status. RESULTS: Forty-six (10.3%) positive BHR cases were identified. In the multivariate logistic analysis, as independent predictors of BHR, adjusted odds ratio of bronchiolitis diagnosed before 2 years of age in low income families was 13.7 (95% confidence interval, 1.4 to 135.0), compared to reference group, controlling for age, gender, parental allergy history, skin prick test, and environmental tobacco smoke (ETS) exposure. Interaction was observed between bronchiolitis before 2 years old and low socioeconomic status on children's bronchial hyperreactivity (p-interaction=0.025). CONCLUSIONS: This study showed that bronchiolitis diagnosed before 2 years of age and low socioeconomic status interacted on children's bronchial hyperreactivity. Prevention of acute respiratory infection in early childhood in low socioeconomic status is important to prevent BHR as a precursor of asthma.

Effects of Volatile Organic Compounds, and Formaldehyde on Heart Rate Variability among Elderly People in Seoul / 대한산업의학회지

OBJECTIVES: The purpose of the present study was to investigate the effects of volatile organic compounds, and formaldehyde on heart rate variability among elderly people who are vulnerable to ambient pollution. METHODS: From May to August of 2009, 57 subjects older than 60 years were recruited in this study. Indoor air pollutants (volatile organic compounds and formaldehyde) were measured by a personal passive sampler. Heart rate variability (HRV) was measured in the sitting position for five minutes and assessed by time-domain and frequency-domain. RESULTS: Multiple linear regression analysis showed significantly less low-frequency (LF) and high-frequency (HF) associated with elevated benzene levels. Exposure to toluene was associated with decreases in the Standard deviation of the NN intervals (SDNN) and LF. SDNN and LF were negatively associated with the increment of ethylbenzene levels. CONCLUSIONS: An adverse effect on cardiovascular function caused by volatile organic compounds was observed among the elderly people of Seoul even though indoor air pollutant levels were lower than the yearly average guideline for indoor air quality in Korea.