close and disagreeable odor of a filthy or
overcrowded room is due to these organic exhalations from the lungs, the
skin, and the unclean clothing of the occupants.

The necessity of having a proper supply of fresh air in enclosed
places, and the need of removal of impure air are thus evident. If a
man were shut up in a tightly sealed room containing 425 cubic feet of
air, he would be found dead or nearly so at the end of twenty-four hours.
Long before this time he would have suffered from nausea, headache,
dizziness, and other proofs of blood-poisoning. These symptoms are often
felt by those who are confined for an hour or more in a room where the
atmosphere has been polluted by a crowd of people. The unpleasant effects
rapidly disappear on breathing fresh air.

219. The Effect on the Health of Breathing Foul Air. People are often
compelled to remain indoors for many hours, day after day, in shops,
factories, or offices, breathing air perhaps only slightly vitiated, but
still recognized as "stuffy." Such persons often suffer from ill health.
The exact form of the disturbance of health depends much upon the
hereditary proclivity and physical make-up of the individual. Loss of
appetite, dull headache, fretfulness, persistent weariness, despondency,
followed by a general weakness and an impoverished state of blood, often
result.

Persons in this lowered state of health are much more prone to surfer from
colds, catarrhs, bronchitis, and pneumonia than if they were living in the
open air, or breathing only pure air. Thus, in the Crimean War, the
soldiers who lived in tents in the coldest weather were far more free from
colds and lung troubles than those who lived in tight and ill-ventilated
huts. In the early fall when typhoid fever is prevalent, the grounds of
large hospitals are dotted with canvas tents, in which patients suffering
from this fever do much better than in the wards.

This tendency to inflammatory diseases of the air passages is aggravated
by the overheated and overdried condition of the air in the room occupied.
This may result from burning gas, from overheated furnaces and stoves,
hot-water pipes, and other causes. Serious lung diseases, such as
consumption, are more common among those who live in damp, overcrowded, or
poorly ventilated homes.

220. The Danger from Pulmonary Infection. The germ of pulmonary
consumption, known as the bacillus tuberculosis, is contained in the
breath and the sputa from