Dr. B. I. Gandelman, Dr. R. F. Galperova,
Dr. I. I. Kandinsky (Moscow)

Clarified Solutions of Chlorinated Lime as a Disinfectant in Residential Settings

From the Moscow Institute of Disinfection

The effort to introduce chlorinated lime widely for the disinfection of dwellings is entirely justified by its ready availability and low cost. Nevertheless, its introduction into practice requires considerable caution and a carefully developed method of application, taking into account, on the one hand, the toxic effect of chlorine and, on the other, the instability of chlorinated lime solutions. Under certain conditions, both properties may produce highly undesirable results and disappoint expectations regarding the bactericidal activity of the substance used. Accordingly, the Institute of Disinfection conducted a series of experiments along these lines, taking as its starting point the work of Smorodintsev and Uspensky (Vrachebnaya Gazeta, no. 2, 1935), which indicated that chlorinated lime solutions were suitable for use as a disinfectant under ordinary residential conditions.

We carried out 15 trials of disinfection in occupied residential premises under practical conditions during the summer. The work included observations of the bactericidal activity of the solution tested and the percentage of chlorine in the air of the rooms treated.

Of the 15 residential premises, 3 had limewashed walls and 7 were covered with wallpaper of various colors and qualities. The premises had a wide variety of occupants and included hotels, dormitories, and private dwellings. Premises with children of various ages were not excluded; in one case an infant was removed only to an adjoining room for 3 hours.

The work was carried out using a concentration of 500 mg of active chlorine per liter of water, which was checked each time by the iodometric method. This concentration was chosen on the basis of published data as producing the greatest bactericidal effect (Boldyrev, Smorodintsev, and Uspensky). In the first 10 trials, 250 cm³ of liquid was used per 1 m² of treated surface; in the last five, 300 cm³ was used. The walls and floor were washed using a hand-operated sprayer. Furniture was wiped down: upholstered furniture with brushes moistened with the liquid, and hard furniture with wet cloths. Linen was not soaked in the test solution because of the risk of discoloration and possible damage to the fabric. Nickel-plated and bronze objects were coated with petroleum jelly; machines, clocks, and radio receivers were removed from the room after thorough damp wiping without chlorinated lime solutions. The walls and floor underwent bacteriological testing to determine the effectiveness of the substance tested. Certain polished objects, which were not to be treated with chlorinated lime, were tested in parallel to assess the effectiveness of simple mechanical cleaning with hot water by wiping. The results are presented in the table.

The destruction of flora on limewashed and wallpapered walls was variable, ranging in both cases from 40 to 74.6%; the effectiveness must therefore be regarded as approximately the same for both types of wall.

When the quantity of liquid was increased to 300 cm³ per 1 m², instead of the 200 cm³ ordinarily used, the percentage of microflora destroyed increased but still ranged from 68.4 to 91.1.

Floor washing, performed either in addition to treatment with chlorinated lime solutions or as a separate procedure—that is, without prior treatment with a chlorinated lime solution—gave equivalent and quite consistent results, with an effectiveness of 92 to 99%.

Treatment of polished objects—tables, sideboards, and chests of drawers—that were not disinfected but merely washed with hot water and then thoroughly wiped gave excellent results on bacteriological testing—

Effectiveness of chlorinated lime solution¹

99.6% mortality of the microflora. This is entirely consistent with the fact that such surfaces are incapable of retaining large quantities of microflora.

We must note the considerably greater effectiveness of chlorinated lime solution reported by Smorodintsev and Uspensky (99.97, 99.3, 99.50%) than in our work, despite the complete identity of both the research methodology and the disinfection technique. This discrepancy prompted us, in the last five cases, to spray the surfaces with 300 cm³ of the test liquid, resulting in some increase in effectiveness.

We must also note the subjective sensations experienced by the entire team: during the first 15–20 minutes of work, irritation of the mucous membranes of the eyes and throat causes a slight cough and stinging in the eyes and, when working in low-ceilinged rooms, tearing. During the second half of the hour, the odor weakens considerably and all the above symptoms disappear. After an hour, when the work is completed in most cases, the odor no longer irritates the mucous membranes; if the windows are then opened wide, the room is completely free of the chlorine odor two hours after work began.

In every case without exception, the residents welcomed the use of the disinfectant solution being tested, preferring it to all other currently accepted agents because of the almost complete

¹ The figures express the percentage mortality of the microflora.

absence of odor two hours after work begins (provided the room is well ventilated).

The second part of the study aimed, as noted above, to determine the percentage of chlorine in the room being disinfected at different stages of the process (the first half-hour, the second half-hour, and the end of the second hour of work). Repeated investigations under varying conditions—room volume, wall finish, ventilation, and the amount of furniture in the room—showed that the percentage of chlorine in the air, even at the beginning of the work, during the first half-hour, was extremely low, remaining at the minimum levels permitted by sanitary standards (0.01–0.02 mg per 1 liter of air). At the end of the second hour of work, no chlorine could be detected in the air in any case (Malchevsky’s test method).

Conclusions

1. Chlorinated lime solutions containing 500 mg of active chlorine per 1 liter of water are entirely suitable for residential disinfection during the summer.

2. Chlorinated lime can readily be used in practice under a variety of residential conditions, except in damp attic and basement rooms with low ceilings, where chlorine has an exceptionally strong effect and consequently causes severe distress to both workers and occupants.

3. The effectiveness of the solution tested does not exceed the generally established results for soap–cresol preparations (Boldyrev, Smorodintsev, Galperova).

4. The effectiveness of the clarified chlorinated lime solutions cited above, reported by Smorodintsev and Uspensky (99.8%), can be achieved in practice only if the surfaces (walls and floor) are very liberally sprayed, using no less than 300 cm³ per 1 m², and are additionally subjected to mechanical wet cleaning (thorough washing of the floor with hot water followed by wiping).

5. The floor could be left untreated with the solution tested and cleaned mechanically instead. However, without sufficient assurance that the cleaning ordinarily performed by the disinfector is thorough, it is not possible to dispense entirely with disinfecting the floor with a disinfectant solution.

6. The smell of chlorine disappears completely two hours after disinfection, provided the room is ventilated; ventilation should begin one hour after the work is completed. The chlorine concentrations used (500 mg per 1 liter of water) are entirely acceptable under practical conditions for disinfecting residential premises.

Instructions for the Use of Weak Clarified Chlorinated Lime Solutions in the Disinfection of Residential Premises

(Applicable during the warm season)

A. General Instructions

I. Weak clarified chlorinated lime solutions are used to disinfect residential premises in cases of intestinal infections (typhoid fever, paratyphoid fever, dysentery) and respiratory infections (scarlet fever, diphtheria).

II. The use of weak chlorinated lime solutions for residential disinfection is permitted provided the following conditions are observed: a) mandatory—

…vacating the premises to be disinfected for the entire period of disinfection and airing; (b) airing the premises for at least 2 hours after disinfection; (c) carrying out disinfection no later than 3 hours before the residents go to sleep.

III. Chlorinated-lime solution must not be used: (a) in damp premises or premises that are difficult to air, especially basements; (b) in family dormitories where children are crowded together; (c) where bulky musical instruments (grand or upright pianos) and metal instruments are present and cannot be removed from the premises.

IV. During terminal disinfection, weak chlorinated-lime solutions are used to disinfect both the living quarters themselves and furnishings and household articles that will not be damaged by them; during ongoing disinfection, they are used only to disinfect cleaning rags and vessels for excreta.

Note: Disinfection with chlorinated-lime solutions involves the following techniques: (a) spraying surfaces (walls and floors) with a hand pump; (b) wiping furnishings and household articles with rags moistened with disinfectant solution; (c) soaking rags and vessels for excreta in disinfectant solution (during ongoing disinfection).

V. Articles damaged by weak chlorinated-lime solutions (colored fabrics and metal objects) are disinfected with other disinfectant solutions: soap–cresol or soap–phenol solutions.

B. Preparation of working solutions

VI. For disinfection, a clarified 0.2% chlorinated-lime solution containing 500 mg of active chlorine per liter is used, prepared according to a separate instruction. The working solution must be at least at room temperature (13–15°C).

When preparing the working solution with hard water (well water), at least 300 cm³ of stock solution must be used per 10-liter bucket.

The disinfection team must keep the 10% stock solution in a dark-glass bottle with a ground-glass stopper.

An enamel bucket is recommended for preparation and use.

C. Calculation of the amount of working solution required for disinfection

VII. At least 300 cm³ of working solution is required for each square meter of surface to be disinfected. The amount is determined according to the following approximate rates:

Г. Methods and technique of decontamination during terminal disinfection

VIII. When using a weak solution of chlorinated lime, it should be borne in mind that, first, chlorinated lime solutions can bleach dyed materials (fabrics); second, metal objects must be protected, given the destructive effect of chlorine on metals; and third, the amount of free chlorine in the air of the room being disinfected depends not only on the total quantity of solution used for disinfection, but also on the presence of soft furnishings in the room, the nature of the walls and floors, the humidity of the air, and other factors.

Accordingly, the following are required: (a) careful selection of objects that would be damaged by chlorinated lime solutions and their disinfection by other means; (b) reduction to a minimum of the time spent spraying the walls and floor of the room with a hand-operated sprayer; and (c) observance of personal protective measures by staff and persons living at the affected premises.

IX. Disinfection with chlorinated lime solution must be preceded by the usual preparation of the room and disinfection of objects that would be damaged by chlorinated lime, in particular: (a) selection and bagging of articles for chamber disinfection; (b) boiling or soaking of linen in soap-cresol or soap-phenol solutions; (c) disinfection of any remaining excreta from the patient; (d) arrangements for boiling dishes; (e) selection of objects that need to be removed from the room and disinfected beforehand, including food supplies, houseplants, and metal objects such as clocks and sewing machines; (f) wiping any bulky metal objects left in the room with disinfectant solution and subsequently coating them with grease (petroleum jelly, oil, or lard); and (g) clearing objects away from the walls to allow unimpeded access for spraying.

X. Only after all preparatory work has been completed and objects liable to damage by chlorinated lime have been disinfected is the working solution of chlorinated lime prepared, the walls and floor sprayed, and furnishings wiped down. In doing so: (a) the disinfector wears enclosed goggles and a respirator while spraying with the hand-operated sprayer; (b) spraying is carried out with doors and windows tightly closed; (c) walls are sprayed with a finely atomized stream of liquid, without producing runnels (when this procedure is followed, wallpaper and painted, whitewashed, and oil-painted walls are not damaged); (d) lacquered and polished objects are disinfected by wiping them with a cloth lightly moistened with the solution; (e) individual drops or splashes of solution must not be allowed to fall on colored furniture upholstery, nor should the upholstery be sprayed; (f) after disinfection, floors are wiped with a cloth to remove excess liquid; and (g) ventilation of the rooms—by opening the windows—is begun immediately after disinfection is completed.

Note. In rooms without wallpaper, the windows are opened immediately after the walls have been sprayed.

(h) Immediately after use, hand-operated sprayers must be rinsed with copious amounts of clean water, then dismantled and their parts lubricated with petroleum jelly; (i) on leaving the site, the disinfection team must instruct the residents to continue ventilating the rooms for at least 2 hours, after which the rooms should be thoroughly cleaned.

Д. Use of weak chlorinated lime solutions for concurrent disinfection

Rags and cloths, as well as receptacles for excreta after they have been emptied, are disinfected with chlorinated lime solutions by soaking or immersing them in the disinfectant solution for 20–30 minutes.

References

1. Boldyrev. Proceedings of the Military Medical Academy, collection 1, 1934.
2. Krupin, S. E. Weekly Clinical Gazette, no. 23, 1885.
3. Rozenberg, N. K. Medical Gazette, no. 3, 1934.
4. Smorodintsev. Hygiene and Epidemiology, no. 8, 1929.
5. Smorodintsev and Uspensky. Soviet Medical Gazette, no. 2, 1935.
6. Khlopin. Military Sanitary Foundations of Antigas Protection, 1926.