Indoor air quality

“ NIOSH recognizes that it may occasionally be necessary to limit CCP exposure in certain workers through administrative controls (such as job rotation) . But in most cases, implementing normal precautions and recommendations for maintaining acceptable indoor air quality should be adequate to reduce or eliminate symptoms. Good industrial hygiene and work practices are likely to prevent symptoms from potent irritants (such as formaldehyde) that may be emitted from CCP. These include adequate ventilation, humidity, and temperature controls ”

“ Ventilation.—Very few people in cities spend more than one hour a day in the open air, which means that they are housed up for the other twenty-three hours, so that no pains should be spared to bring up the quality of the indoor air to approximate as nearly as possible that of the outdoor air. The air of houses contains many more microbes than that of the street.
For dwelling-houses 3000 cubic feet of fresh air is needed every hour. It is said that in the country the only bad air is in farmers’ houses, whence it has no chance to escape. ”

“ It seems, at any rate, to give the air a lifeless quality, which soon imparts itself to the victim of our wasteful modes of heating.
Apparatus for artificial moistening, which is now often installed in connection with heating and ventilating systems, aside from the liability of exceeding the desirable humidity, also gives opportunity for contamination of the air supply. Unless the devices are designed on sanitary principles and intelligently attended to, they are very liable to become foul and malodorous, if not unhealthy. ”

“ The latest evidence submitted at the Royal Institute of British Architects and at the International Congress of Hygiene, Budapest, has conclusively demonstrated that heated air employed for the double purpose of ventilation and warming is not only unhealthy, but fails as an efficient heating medium. ”

“ By thus applying the principles of colliery ventilation to350 a specially-constructed house, we may, I believe, obtain a perfectly controllable indoor climate, with a range of variation not exceeding four or five degrees between the warmest and the coldest part of the house, or eight or nine degrees between summer and winter, and this may be combined with an abundant supply of fresh air everywhere, all filtered from the grosser portions of its irritant dust, which is positively poisonous to delicate lungs, and damaging to all. ”

“ Its other smoke-impurities, dirts and dusts, escape, or are blown away so rapidly that they are seldom thick enough to be injurious to health, except in the narrowest and darkest streets; so that it is always safe to open your windows wide for air, wherever you may live. The principal danger from smoke is that it cuts off the sunlight.
The Necessity for Ventilation—Impurities of Indoor Air. The worst impurities in air are those that come from our own breaths and our own bodies; and, unexpectedly enough, carbon dioxid is not one of them. ”

“ But we, of this generation, can not afford to wait for natural selection to fit the race to an indoor environment; hence the supreme importance to us of air hygiene. We must compensate for the construction of our houses by insisting on open windows, or forced drafts, or electric fans, or open-air outings, or sleeping porches, or the practise of deep breathing, or all of these things. ”

“ Whatever may be the impurity of the out-door air of any locality, the in-door air of that locality is still more impure, because of the dust, and decaying and odoriferous matters which are found in all dwellings. Besides, how can in-door air be more healthy than the out-door air, other things being equal, when the dwelling is supplied with air from without? ”

“ Without doubt, it is true that so far as quality is concerned our best standard is the external air surrounding the building to be ventilated. Investigation also indicates that the utilization of the external air for natural ventilation by raising the windows and regularly admitting the air to the apartment to be ventilated is desirable when the conditions are favorable. Generally speaking, it is not desirable to have a system bf ventilation which will not permit the direct communication with the outside air by the opening of windows. ”

“ In dwelling-rooms natural ventilation by doors, windows and chimney usually suffices, especially if the products of combustion of gas are removed through a special flue. Natural ventilation is always occurring, and only needs a little aid in domestic life. For large rooms occupied by many persons artificial ventilation is necessary to maintain pure air. ”

“ In order to keep down the percentage of pollution to a non-dangerous degree, under this system arises, therefore, the necessity of admitting for ventilation fresh air in quantities many times greater than that actually used for breathing, and also a correspondingly extravagant expenditure of heat if this supply be artificially warmed. Thus the only ideally perfect ventilation consists in inducing a regular upcurrent from a level below that of the human head up to the extraction outlets at the ceiling. ”

“ Our ordinary dwelling-houses need not be ventilated artificially; we ought never so to crowd them that the natural means of ventilation, as difference of temperature, motion of the air in the open, dry and porous walls, and temporary assistance by the architectural openings, are insufficient to keep undeteriorated what is most essential for our health. With these means there must go hand-in-hand the greatest cleanliness in all parts of the house, and abstention from all superfluous and avoidable pollution of the air of the house. ”

“ Humidity levels can rise in a building as a result of the use of humidifiers, steam radiators, moisture-generating appliances such as dryers, and combustion appliances such as stoves. Cooking and showering also can add to indoor humidity. ”

“ Indoor air is, however, the main subject of investigation, and experiments prove that ventilation which completely changes the atmosphere three times an hour will not appreciably affect the number of bacteria in an apartment, as the intruders cling obstinately to the carpets and upholstery. Only violent currents of air dislodge these, and the sweeping and cleansing which result in removing, not redistributing the dust. Ordinarily we are liable to take in with every twenty breaths from eleven to eight hundred and seventy-six organisms. ”

“ Artificial ventilation therefore becomes imperative. Natural ventilation by opening windows and doors can only be practised in intervals of work and as a rule only in small workrooms. During work time the draught and reduction of temperature so caused produce discomfort.
Artificial ventilation is effected by special openings and ducts placed at some suitable spot in the room to be ventilated and arranged so that either fresh air is introduced or air extracted from the room. The first method is called propulsion, the latter exhaust ventilation. ”

“ The efficient ventilation of a theater building is conceded to be an unusually difficult problem. In order to ventilate a theater properly, the causes of noxious odors arising from bad plumbing or defective drainage should be removed; outside fumes or vapors must not be permitted to enter the building either through doors or windows, or through the fresh-air duct of the heating apparatus. The substitution of electric lights in place of gas is a great help toward securing pure air. This being accomplished, a standard of purity of the air should be maintained by proper ventilation. ”

“ The choice, therefore, so far as ventilation of either house or barn goes, lies between a poorly built, loose-jointed structure without artificial ventilation and with poor economy in heat, and a well-built, air-tight structure, with ample ventilating pipes, carefully and intelligently planned and built. The first is healthy so far as pure air is concerned, but drafty and uncomfortable. The second is more expensive to build, but insures lasting health and comfort. Then the choice cannot but fall on the building which is easy to warm, healthful to live in, and readily ventilated. ”

“ Effective sanitary ventilation should supply gentle and uniformly-diffused currents of air of moderate and equal temperature throughout the house. We talk a great deal about the climate here and the climate there; and when we grow old, and can afford it, we move to Bournemouth, Torquay, Mentone, Nice, Algiers, etc., for better climates, forgetting all the while that the climate in which we practically live is not that out-of-doors, but the indoor climate of our dwellings, the which, in a properly constructed house, may be regulated to correspond to that of any latitude we may choose. ”

“ It is also, unfortunately, true that, as ordinarily arranged, they make the worst possible devices for warming the air of our rooms. Heating should always be combined with ventilation, that is, there [50] should be a continuous removal of the fouled air and introduction of plenty of pure air instead, but arranged so as not to cause inconvenient or unhealthy drafts. A room warmed by an air-tight stove must soon contain air entirely unfit to breathe, for a close stove removes practically none of the vitiated air, and there is usually an entire absence of any provision for introducing fresh air. ”

“ Secondary air quality standards "specify a level of air quality the attainment and maintenance of which in the judgment of the Administrator, based on such criteria, is requisite to protect the public welfare from any known or anticipated adverse effects associated with the presence of such air pollutant in the ambient air." ”

“ As to dryness of air, there is little which the individual can do except to choose a dry climate in which to live or spend his vacations. Unfortunately, there is not as yet any simple and cheap way of drying house air which is too moist, as is often the case in warm weather.
Humidity
In the cold season, indoor air is often too dry and may be moistened with advantage. This may be done, to some extent, by heating water in large pans or open vessels. But for efficient moistening of the air, either a very large evaporating-surface or steam jets are required. ”

“ Theaters and crowded assembly halls, class rooms, hospitals, certain laboratories and workshops, hotel kitchens, public smoking and toilet rooms, generally need a rapid renewal of air. The ventilation of such places should be positive, that is, it should not be dependent to any extent upon weather or temporarily favorable conditions. Of course, when subject to spontaneous ventilation, such rooms will require less of the artificial kind. Indeed, it is important always to utilize the natural means at hand, and to omit none of the preventive measures that may help to relieve the situation. ”

“ The principal reason why the demand for moisture in heated rooms has arisen is the irritating effect of floating dust which has been set in motion by the heating system, directly or indirectly. In the worst form this may be noticed with hot-air heating through floor registers, which invite all sorts of rubbish to fall into the flue, only to be dried and sent up again, often directly into one's nose. ”

“ Ventilation can render air even better than the outdoor variety by purifying it of dust and by supplying it with the right amount of moisture and motion.
For the ordinary home the great air conditioners and ozonators, which are installed in institutions and factories, are unnecessary, so we will not consider them. The best, simplest and least expensive ventilating system for the home is the system regulated by fans and blowers, and to this method we will introduce ourselves. ”

“ The leading idea should be to give the most advantageous direction to the natural currents of air. Systematic supply of fresh air, combined in some form with the heating apparatus, is appropriate in many cases, particularly as it permits some control over the purity, temperature and humidity of the air entering the building.
Mechanical or forced ventilation finds application where the number of people, excess of heat, or other conditions creating unwholesome atmosphere, can not be overcome by any other method. ”

“ Natural ventilation which is dependent upon windows, porosity of building materials, cracks in the floors, &c., fails when, as is desirable for purposes of cleanliness, walls and floors are made of smooth impermeable material, and natural ventilation will rarely supply the requisite cubic feet of fresh air quickly enough. ”

“ Furthermore, experience shows that in order to ensure reliability it is necessary to have a separate flue for almost every room and to locate the radiators, directly beneath the vertical flue, so that in buildings of any size, especially those more than one or two stories in height, the arrangement of radiators in the basement becomes difficult, and the system of air flues, which are necessarily large, is complex and expensive in space and also in construction. ”

“ Outlets, under ordinary circumstances, are best placed near the ceiling. They should be enclosed as far as possible within walls, so as to prevent the outgoing air being cooled; and should have smooth walls, reducing friction to a minimum. Where artificial warmth increases the temperature of the air, the discharge of outlets is much more certain and constant. The chimney with an open fire forms one of the best outlets. Gas, again, may be made to heat an outlet tube, which carries off the products of combustion.
Two forms of ventilation are usually described—natural and artificial. ”

“ Attempts at ventilation are made by utilizing the heat due to the numerous flames of the central chandelier over the auditorium, to create an ascending draught, and thereby cause a removal of the contaminated air, but seldom is provision made for the introduction of fresh air from outdoors, hence the scheme of ventilation results in failure. In other buildings, openings for the introduction of pure air are provided under the seats or in the floor, but are often found stuffed up with paper because the audience suffered from draughts. ”