Sources of Impurities in Air
There are many processes carried on within the house that add to the impurities of the air. Such sources may be classified as follows: respiration of persons, impurities from heating and illumination, and accidental sources from processes carried on within the house, such as house cleaning and laundering.
It will be observed from a study of the amount of air inspired and expired and the impurities carried from the body in the process that one of the most common sources of vitiation of the air in houses is respiration. That these expired poisons may be diluted or carried out of the breathing zone it becomes necessary to have an adequate ventilating system. If the room is heated by a stove impurities will be added from coal dust and the dust of ashes. When the iron is overheated it gives off carbon dioxide and other gases. Open fire or an open blaze for lighting purposes consumes oxygen, gives off carbon dioxide, raises the temperature and increases the amount of aqueous vapor.
Vitiation from accidental sources consists of dust particles of organic and inorganic detritus which are added to the air from walls, floors, furniture and hangings. Other processes such as laundering will add a certain amount of poisons and suspended matter to the air. All this reveals the necessity for exchanging the inside air for pure outside air.