Lighting by electricity is preferable to lighting by gas, as some of the gas is liable to escape and vitiate the air.
Tobacco Smoke
A very common and at the same time injurious form of air-vitiation is that from tobacco smoke. Smoking, especially in a closed space such as a smoking-room or smoking-car, vitiates the air very seriously, for smoker and non-smoker alike.
Dust
As to dust, the morbidity and mortality rates in certain occupations, particularly those known as the dusty trades, are appreciably and even materially greater than in dustless trades.
An accumulation of house-dust should be avoided. The dust should be removed—not by the old-fashioned feather duster which scatters the dust into the air—but by a damp or oiled cloth. Dust-catching furniture and hangings of plush, lace, etc., are not hygienic. A carpet-sweeper is more hygienic than a broom, and a vacuum cleaner is better than a carpet-sweeper. The removable rug is an improvement hygienically over the fixed carpet.
Bacteria
The bacteria in air ride on the dust-particles. In a clean hospital ward, when air was agitated by dry sweeping, the number of colonies of bacteria collected on a given exposure rose twenty-fold, showing the effect of ordinary broom-sweeping.
Sunlight
The air we breathe should be sunlit when possible. Many of our germ enemies do not long survive in sunlight.