certainly is a condition that tends to keep people from coming here and makes people desirous of leaving at the first opportunity.” The writer of this essay has now lived in Pittsburgh somewhat over a year and has experienced during this time a marked distaste or disinclination to engage in productive authorship. Clear, trenchant, reflective thinking seems to have been more difficult; and the attempt to write concisely, incisively and perspicuously has seemed more labored. Is it possible that the low esteem in which Pittsburgh is held in the world of productive scholarship--a matter of occasional remark among medical men and other scientists--is due to the fact that the air which its scientists must breathe is polluted and poisoned by smoke? [There are other contributory factors, as we shall see in the following sections, viz., the various devitalizing weather states induced by smoke, and possibly the common use of convection heat from gas stoves in the living rooms. Convection heat from gas stoves, it is maintained by Scotch investigators, is more injurious than heat by radiation (21).] Is it possible that the highest spiritual creations of the citizens of smoke-begrimed cities are being sacrificed on the altar of commercial greed? Is it possible that, in the interests of a pseudo-economy, we are impairing the very brains of the people by permitting our breathing air to be saturated with the poisons of preventable fumes? Is it possible that the industrial energy for which Pittsburgh has become famous is less due to the surpassing excellence of the brain and brawn of its workers than to the munificent bounty of its mines? We shall probably not be able to offer any satisfactory answer to questions such as these until a series of controlled psychological experiments on efficiency, fatigue, and endurance (in so far as various motor, sensory, and intellectual functions are concerned), have been carried out under varying degrees of density of atmospheric smoke. _B. The indirect influences of smoke on mental and physical well-being; the meteorological aspects of atmospheric smoke contamination._ I shall first discuss the meteorological variations produced by smoke, and then the effects of the smoke-produced weather states upon well-being.