Used in two ways. First, the number of times that the outdoor air replaces the volume of air in a building per unit time, typically expressed in air changes per hour; second, the number of times that the ventilation system replaces the air within a room or area within the building.

Air leakage into a building.

Inability to initiate changes in activity and to perform ordinary volitional movements rapidly and easily. It is the most disabling feature of Parkinson's disease.

A substance capable of causing an allergic reaction because of an individual's sensitivity to that substance.

(plural = alveoli) A small microscopic sac that is the functional unit of the lung, the location at the far end of the respiratory tract where gas exchange occurs.

A unicellular organism which may either obtain energy by means of photosynthesis or by ingesting other organic material. The organism has no wall or coat outside its cell membrane; it moves and feeds by means of pseudopodia.

Coordinates autonomic and endocrine responses in conjunction with emotional states; part of the limbic system.

A disease marked by brief, sudden attacks of chest pain precipitated by a deficient supply of oxygen to the heart muscles (also known as angina of the chest or angina pectoris).

Tiny scales of animal skin.

A biological response to exposure to a single chemical interfering with the action of another or to multiple chemicals interfering with each other's actions.