Derivation of physiological inhalation rates in children, adults, and elderly based on nighttime and daytime respiratory parameters

Abstract

The methodology developed in our previous studies () for the determination of physiological daily inhalation rates was improved by integrating into the calculation process, both nighttime and daytime respiratory parameters, namely oxygen uptake factors (H) and ventilatory equivalents (VQ). H values during fasting (0.2057 ± 0.0018 L of O₂/kcal; mean ± SD) and postprandial phases (0.2059 ± 0.0019 L of O₂/kcal) as well as VQ values for subjects at rest (27.4 ± 4.8 to 32.2 ± 3.1, unitless) and during the aggregate daytime activities (29.9 ± 4.2 to 33.7 ± 7.2) were determined and combined with published doubly labeled water measurements for the calculation of daily inhalation rates in normal-weight males and females aged 0.22–96 years (n = 1235). Depending upon the unit value chosen, the highest 99th percentiles for inhalation data were found in males aged 35 to <45 years (35.40 m³/day), 2.6 to <6 months (1.138 m³/kg-day), and 10 to <16.5 years (22.29 m³/m²-day). Means and percentiles expressed in m³/kg-day as well as in m³/m²-day suggest generally higher intakes of air pollutants in children than in adults and in males than in females (in µg/kg-day or µg/m²-day) for identical exposure concentrations and conditions. For instance, means in boys aged 2.6 to <6 months of 10.99 ± 3.50 m³/m²-day and 0.572 ± 0.191 m³/kg-day are 1.3- and 2.5-folds higher, respectively, than those in adult males 65–96 years old (8.42 ± 2.13 m³/m²-day, 0.225 ± 0.059 m³/kg-day).

Keywords::

• Daily inhalation rates
• oxygen uptake factor
• ventilatory equivalent
• doubly labeled water
• health risk assessment

Acknowledgements

The authors are grateful to Mrs. Jacqueline Levesque and Mrs. Lise Fiset from the Cécile-Rouleau Library for their contribution to this project. They also wish to thank Mr. André Thibault for his contribution to the review of the literature in regards to the correlation between sleep curtailments and higher BMIs, as well as Mr. Jean-François Ducré-Robitaille and Mr. Bernard Caron for their constructive statistical comments. Appreciation is also expressed to Mr. John Francis Niederreiter and Mrs. Meghan Howell for the linguistic revision of this manuscript.

The authors wish to point out that the views expressed in this paper may not reflect the official policy of the Québec Ministry of Sustainable Development, Environment and Parks.

Declaration of interest

The authors report no conflicts of interest.