In response to higher altitude, the body's diffusing capacity increases in order to process more air.

When someone living at or near sea level travels to locations at high altitudes (e.g. the Andes; Denver, Colorado; Tibet; the Himalayas) that person can develop a condition called altitude sickness because their lungs remove adequate amounts of carbon dioxide but they do not take in enough oxygen.

Lung function development is reduced in children who grow up near motorways[5][6] although this seems at least in part reversible.

Functional residual capacity drops 18–20%,[9] typically falling from 1.7 to 1.35 litres,[citation needed] due to the compression of the diaphragm by the uterus.

[15] Online calculators are available that can compute predicted lung volumes, and other spirometric parameters based on a patient's age, height, weight, and ethnic origin for many reference sources.

[20] A half litre ordinary tidal breath[11] weighs 0.6 g; a maximal 4.8 litre breath (average vital capacity for males)[11] weighs approximately 5.8 g. The results (in particular FEV1/FVC and FRC) can be used to distinguish between restrictive and obstructive pulmonary diseases: