Document g5jeKgG3MvnoYKXQyJpxvpG3

HEATING VENTILATING AIR CONDITIONING GUIDE 1944 cramps to excessive loss of body chlorides and heat stroke to an inade quacy of the heat dissipating mechanism which results in heat retention. If the hyperthermia becomes excessive, the liver and the central nervous system may be seriously injured and this damage may prove fatal. The hazards of high temperature are not understood. It is difficult to say whether short exposures at high temperatures are more harmful than longer exposures at lower temperatures. A new concept is evident from the observation of an increase in leucocytes (white cells) of the blood in workers subjected to high temperatures. These leucocytes are defensive factors which are increased when infection invades the body. A rise in temperature and leucocyte count indicates a mobilization of the body defenses. Since a recent study34 showed that both temperature and cell count were increased, the question arises as to whether long exposures to very high temperatures might not cause exhaustion of these defense mechanisms. ALLERGIC DISORDERS Although there is some division of opinion over the ultimate cause of allergy, the prevailing belief is that it is due to an inherited or acquired hypersensitiveness to pollen or-other foreign proteins in certain indivi duals who react abnormally to the offending substance. The reaction may be induced by inhalation, eating, or absorption (through the skin) of the allergens. Some of the clinical manifestations are hay fever, asthma, eczema, and contact dermatitis. Symptoms oi Hay Fever and Asthma The respiratory tract is the usual site of allergic manifestations, e.g. hay fever and asthma. In hay fever, the nose and eyes are red and itchy, and there is considerable discharge. Nasal obstruction is the most common and distressing symptom. The severity of the symptoms varies widely from day to day depending chiefly on the amount of pollen in the air. _, . Seasonal asthma comes in attacks. The most populartheory concern ing the mechanism of action is that the offending substance irritates the nerve endings in mucous membranes of the respiratory tract, causing spasmodic contraction of the small bronchioles of the lungs, which interferes with breathing, particularly with expiration. Non-seasonal allergic disturbances are sometimes attributed to house or street dusts, fungi, odors, animal dander, irritating gases, and heat or cold, particu larly sudden temperature changes. It is. often stated in the literature, that heat regulation in asthmatic individuals is likely unstable, with a tendency toward the subnormal. Many allergic cases who are apparently well, develop their attacks when cold weather appears, or upon changing from warm to cool outdoor air. Air Conditioning Apparatus In recent years considerable effort has been directed toward the elimi nation of the principal cause of allergy from the air of enclosures by "A.S.H.V.E. Research Report No. 1106--Air Conditioning in Industry, by W. L. Fldsher, A. EStacey, Jr., F. C. Houghten and M. B. Ferderber (A.S.H.V.E. Transactions, Vol. 45, 1939, p. 59). 692 CHAPTER 37. AIR CONDITIONING IN THE TREATMENT OF DISEASE filtration or other air conditioning processes capable of removing pollens, in the hope of providing relief to individuals who fail to respond to medical treatment (desensitization or immunization). Paper or cloth filters, mounted in inexpensive window or floor units, prove quite satisfactory, but since dust and smoke frequently cause asthmatic attacks, it is necessary that an air filter, to be of full value in the treatment of asthma, must remove all dusts and pollens regardless of size or amount. An electrostatic cleaner has proved extremely efficient in removing particles of 15 to 20 microns and smaller, besides dusts and smoke35. Although the chief remedial factor in the treatment by conditioned air is the filtration of pollen, a certain amount of cooling and dehumidification appears to be desirable. A comfortable temperature between 70 and 75 F and a relative humidity well below 50 per cent proved satisfactory38. Direct drafts, overcooling or overheating are apt to initiate or aggravate the symptoms. Limitations oi Air Conditioning Methods The results-obtained with air filtration or other air conditioning pro cesses in the control of allergic conditions are fairly comparable to those obtained by desensitization treatment so long as the patients remain in the pollen free atmosphere. But while specific desensitization is preven tive and in a few instances curative, for ail practical purposes filtration gives only temporary relief. In mild cases sleeping in an air conditioned space may make it possible for the individual to pass more comfortable days. With rare exceptions, the symptoms recur on exposure to pollen laden air. Moreover the usefulness of air conditioning methods is limited because all cases are not caused by air-borne substances. Cases of bacterial asthma do not respond to the treatment with filtered air. Despite these limitations air conditioning methods possess definite advantages in the simplicity of treatment, convenience, and under certain conditions almost immediate relief37. Pollen cases are usually relieved of most of their symptoms within 1 to 3 hr after exposure to properly filtered air. A pollen-free atmosphere is especially valuable in cases where desensitiza'tion has given little or no relief, and where desensitization is not advisable owing to intercurrent illness. OXYGEN THERAPY Oxygen therapy is the principal measure employed for preventing andrelieving the distressing symptoms of anoxemia, which is a deficiency in the oxygen content of the blood. Some of the more important conditions, in which oxygen treatment is believed to be beneficial are pneumonias, "Air Cleaning as an Aid in the Treatment of Hay Fever and Bronchial Asthma, by Leo H. Criep and M. A.-Green (Journal of Allergy, 7:120, 1936). "The Effect of Low Relative Humidity and Constant Temperature on Pollen Asthma, by B. Z. Rappaport, T. Nelson and W. H. Welker (Journal of Allergy, 6:111, 1935). "Hospital Air Conditioning, by C. P. Yaglou (The Environment and Its Effect upon Man, Harvard School of Public Health, p.244,1939). 693