Due to their design, such tubes sample end-exhaled air if the tube volume is less than the alveolar air
To correct for dilution of alveolar air
from dead volume air in the breath sample and to normalize the concentration of each analyte to correctly reflect the breath concentration, we measured the carbon dioxide concentration in each canister sample using a C[O.sub.2] monitor (Piton model SC-300; Piton Corp., Menomonee Falls, WI) equipped with an external infrared C[O.sub.2] sensor.
Two other studies found chloroform, a trihalomethane, in the blood, urine, and alveolar air
of swimmers and attendants at indoor swimming pools (16,17).
Although the red blood cells are exposed to alveolar air
only for a fraction of a second, gas exchange between alveoli and capillaries takes place very efficiently because there is an extremely large surface area between the blood and the air.
Second, the sample should preferably consist of alveolar air
, i.e., expired breath involved in the blood gas interface deep in the alveoli with minimal contribution from the tracheal dead volume.
Portable units for analyzing the CO content of expired alveolar air
offer a noninvasive measure.
First, the researchers observed enlargement in the alveolar air
space of the rats' lungs.