A manual of practical hygiene / by Edmund A. Parkes ; edited by F.S.B. Francois de Chaumont.

Date:
1878
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Licence: Public Domain Mark

Credit: A manual of practical hygiene / by Edmund A. Parkes ; edited by F.S.B. Francois de Chaumont. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

    187/820 (page 141)
    SECTION L QUANTITY OF AIR REQUIRED. 1. Quantity required to remove the respiratory impurities caused by healthy persons. The impurities added to the air by respiration have been already enumerated (p. 105). The carbonic acid winch an adult man adds, to the extent of about j^-ths of a cubic foot in an hour, is not within certain limits an important impurity, but it is practically in a constant ratio* with the more important organic matter of respiration; and, as it is readdy determined, it is taken as a conve- nient index to the amount of the other impurities, f Taking the carbonic acid as the measure of the impurity of the air vitiated by respiration (and by respiration alone)4 we have to ask, What is to be considered the standard of purity of air in dwelling-rooms? We cannot demand that the air of an inhabited room shall be absolutely as pure as the outside air; for nothing short of breathing in the open air can ensure perfect purity at every respiration.§ In every dwelling-room there will be some im- purity of air. The practical limit of purity will depend on the cost which men are willing to pay for it. If cost is disregarded, an immense volume of air can be supplied by mechanical contrivances, but there are comparatively few cases in which this could be allowed. Without, however, attempting too much, it may be fairly assumed that the quantity of air supplied to every inhabited room should be great enough to remove ad sensible impurity, so that a person coming from the external air should perceive no trace of odour, or difference between the room and the out- side an in point of freshness. Taking the carbonic acid as the index of im- purity, it appears, from experiments made by Dr de Chaumont and mvself that the organic impurity of the air is not perceptible to the senses untd the carbonic acid (i e the initial and the respiratory carbonic acid) rises to the ratio of -6 per 1000 volumes, or -0006 in each cubic foot. Occasionally air Ik* ^itis P1^^^ in a constant ratio, because it is so in perhaps 99 c™»s m,+ „f im though there may be exceptional cases when the organic matrpr m^ Vo out of 100, for adult men, the amount of -6 cubic feet per ho^TleT^^^l^- J tbinkf perfect experiment yet made is by Pettenkofer, who in a man a°ed fs? ™H w T*n ™-?st grammes (=132 lb avds.), and taking little muscular exertbn ^ nAlf w,e,ghmg .6j> ho- nours amount to 911-5 grammes, or 461 litres a 0° cent rhU T carbonic aad in 24 per hour. The actual amounts'were 078in the ayt me SoinJItTrt t0 '6? °UW? foot at night in a state of repose. This gives 0-0042 Ne7lb Tbodv wpW^ ? WOrk > <\nd °'56 in very gentle exertion1. During hard work theP same man.3 .S ^T' and °-0059 per ft of body-weight. As we may, however, take the ZrZl nt i Pf h°,Ur' 0r °'015 soldiers) at 145 to 150 lb, the amount evolved in deposewould WS °S 2??? ?&? (snc]] as The assumed amount -6,' is therefore, for adult mX will wtthfn ft? °t15,t0 °'636 PT hour' in this case. ' WeU Wltln the actual amount observed + One of the earliest observers to recognise the valup nf oo^i • -j . , appears to have been P. le Blanc, whose Z r L?'110110!^ an index of purif y, GYml,ne(1842), is citedby General Mo'rin. He aXlW1.''1' la ^position de l'Air of ai,- necessary than most of his contempoffi had clearer notions as to the amount + l™8' of course, includes transpiration, or carbonic nniri avT,„i„.» * xi way ; but excludes all other sources, such as lichts hvl In ™ th<J perSOn in auy § Thus the carbonic acid in the air being taken ar .'nfSL <. respiration being placed at -6 cubic feet in an hour fJtt1 . ™d th° 2a&0nio acu] <* of air must receive no less than 1,000,000 ofi feea- rO0m, 011000 cubic fe<* carbonic acid to the standard (nearly -0401 per cent ) of ?i? f f'! n1^ t0 reduce the Cubic Space. By Dr de Chaumont Assistant Pt ' th.°Jres.h air-~°» Ventilation and Edinburgh Med. Jour. May 1867 A8S1Stant Professor of Hygiene, Army Medical School