Influence of Atmospheric Parameters and Pollutants on Control of Breathing in Healthy Neonates

Introduction

There is increasing emphasis on health effects related to air pollution, particularly in the respiratory system. Many studies demonstrate an association between short-term exposure to various urban air pollutants such as nitrogen dioxide (NO), ozone (O), sulfur dioxide (SO), PM (airborne particles with an aerodynamic diameter <10 µm), and respiratory symptoms like cough,1, 2 bronchitis,2–4 wheezing,3–5 and asthma.4–7 Detrimental effects of air pollution have been found to act on both a short-term and long-term basis. Besides good evidence for acute effects on respiratory symptoms and lung function,8–10 it has been shown that long-term exposure to ambient air pollution increases respiratory symptoms in children11 and is related to decreased lung function and impaired lung growth in children.8, 12–15 Urban pollutants are also known to be a cause of preterm birth16 and infant death such as Sudden Infant Death Syndrome (SIDS), neonatal, and postneonatal death,17–19 especially due to respiratory causes.16, 20 We previously have shown that long-term exposure to PM during pregnancy is related to an increase in minute ventilation in neonates, suggesting an impact of prenatal air pollution on lung function.21

Abstract

Exposure to air pollution increases the risk of Sudden Infant Death Syndrome and thus potentially influences control of breathing. This raises the question of whether tidal breathing parameters related to the control of breathing are influenced by atmospheric conditions and air pollution on the day of measurement (DOM).

In a prospective birth cohort study of 175 healthy term infants, we measured tidal breathing parameters including tidal volume, respiratory rate, minute ventilation, inspiratory time to total breath time (T _I/T _tot), ratio of time to peak tidal expiratory flow to expiratory time (T _PTEF/T _E), and peak tidal inspiratory flow at the age of 4-5 weeks. We assessed the association of these tidal breathing parameters with postnatal environmental tobacco smoke exposure (ETS), local atmospheric parameters, pollution levels of nitrogen dioxide (NO₂), ozone (O₃), and airborne particles with an aerodynamic diameter <10µm (PM₁₀) on the DOM using multiple linear regression analysis and adjusting for anthropometric data.

We found no consistent evidence of an association between atmospheric parameters, outside temperature and humidity, and tidal breathing parameters when adjusting for multiple testing. Anthropometric data (postconceptional age, length, and sex) were associated with control of breathing but not urban pollutant levels and ETS on the DOM.

Tidal breathing parameters, which are normally used to determine the maturational state of breathing control in infants, are influenced by anthropometric parameters. The acute effects of outside temperature and humidity, postnatal ETS, and outdoor air pollution levels on the DOM for the control of breathing were negligible in our study of healthy term infants.

Keywords

infant, risk factor, pollution, cohort study, control of breathing