Methods of determination of со
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Тopic №11 METHODS OF DETERMINATION OF СО2 CONCENTRATION АND AIR OXIDABILITY AS THE INDICATORS OF THE ANTROPOGENIC AIR POLLUTION AND PREMISES VENTILATION 1. Learning objective
2. Basics 2.1. You should know: 2.1.1. Physiological and hygienic significance of the air components and their influence on the human health and sanitary conditions. 2.1.2. Sources and indicators of communal, domestic, public and industrial air pollution, their hygienic regulations. 2.1.3. Indoor air circulation. Types and classification of the indoor ventilation, main parameters of the ventilation efficiency. 2.2. You should have the following skills: 2.2.1. To determine of the carbon dioxide concentration in the air and assessment of the indoor air purity. 2.2.2. To calculate of the required and actual volume and rate of the indoor ventilation. 3. Self-training questions 3.1. Chemical composition of the atmospheric and expired air. 3.2. Main communal, domestic, public and industrial air pollution sources. Criteria and indicators of the air pollution (physical, chemical, bacteriological). 3.3. The residential indoor air pollution sources. The air oxidability and carbon dioxide as sensitive indirect characteristics of the air pollution by people. 3.4. Influence of the various carbon dioxide doses on the organism. 3.5. Express methods of the carbon dioxide concentration determination in the air (methods by Lunge-Zeckendorf, Prokhorov, interferometrical). 3.6. Indoor ventilation and its hygienic significance. Types and classification of the ventilation of the communal, domestic and industrial premises. 3.7. Indicators of the ventilation efficiency. The required and actual volume and ventilation rate, methods of their determination. 3.8. Air conditioning. The principles of air-conditioners constructions. 4. Self-training assignments 4.1. Calculate the carbon dioxide volume expired during one hour by person performing the physical activity under calm conditions. 4.2. Calculate the required ventilation volume for a patient in the ward and for a surgeon on the day of the operation. (see appendices). 4.3. Calculate the required ventilation rate of the 4-bed ward with the 30 m2area and 3.2 m ceiling height. 5. Structure and content of the lesson This is a laboratory lesson. At the beginning of the lesson students will have their knowledge of basics checked. After that students receive individual tasks and, using the appendices and recommended literature, determine the concentration of carbon dioxide in the air of the laboratory and outside (atmospheric air), perform the required calculations and draw a conclusion based on the results; calculate the required volume and rate of the laboratory ventilation in accordance to the number of people present, and heaviness of their physical activity; measure the air volume, coming into or being drawn out of the indoor, calculate the actual volume and rate of the ventilation, draw the grounded conclusions and give recommendations. The practical part is to be written down in the protocol. 6. Literature 6.1. Principal: 6.1.1. Загальна гігієна. Пропедевтика гігієни. /Є.Г.Гончарук, Ю.І.Кундієв, В.Г.Бардов / За ред. Є.Г. Гончарука. – К.: Вища школа, 1995. – С. 118-137. 6.1.2. Общая гигиена. Пропедевтика гигиены. / Е.И.Гончарук, Ю.И.Кундиев, В.Г.Бардов и др. – К.: Вища школа, 2000. – С. 140-142. 6.1.3. Минх А.А. Методы гигиенических исследований. – М., 1971. – С.73-77, 267-273. 6.1.4. Загальна гігієна. Посібник до практичних занять. /І.І.Даценко, О.Б.Денисюк, С.Л.Долошицький та ін. / За ред. І.І. Даценко. – 2-ге вид. – Львів: „Світ”, 2001. – С. 59-66. 6.1.5. Габович Р.Д., Познанский С.С., Шахбазян Г.Х. Гигиена. К.: Вища школа, 1983. – С. 45-52, 123-129. 6.1.6. Lecture materials. 6.2. Additional: 6.2.1. Даценко І.І., Габович Р.Д. Профілактична медицина. Загальна гігієна з основами екології. – К.: Здоров’я, 1999. – С. 6-21, 74-79, 498-519, 608-658. 6.2.2. СНиП П-33-75. Отопление, вентиляция и кондинционирование воздуха. Нормы проектирования. – М., 1975. 7. Equipment required for the lesson
Appendix 1 Hygienic characteristics of the indoor sanitary condition and ventilation
The air is pure if this index doesn’t exceed 4-6 mg/m3. The oxidability air index may be 20 and above mg/m3 in the rooms with the adverse sanitary state. 5. Indoor carbon dioxide concentration is increased proportionally to the number of people and duration of their stay inside. Although it normally does not reach the hazardous levels, nevertheless it does indicate the level of the air pollution with the other metabolism products. The carbon dioxide concentration may reach the hazardous for human organism or even life level only in the enclosed non-ventilated areas (dug-outs, submarines, underground openings, industrial areas, sewer systems etc.) due to fermentation, combustion, putrefaction. The increase of the СО2 concentration by 2-2.5% does not cause noticeable deviations in the human health and work ability, according to the research by M.P. Brestkin and other authors. Concentrations up to 4% may cause the increase in the respiration intensity, the cardio-vascular functions and reduction of the work capacity. Concentrations up to 5% are accompanied with dyspnea, increase of the cardiac function, decrease of workability. 6% СО2 concentration causes the mental activity decrease, the headaches, dizziness; 7% causes the inability to control oneself, fainting and even death. 10% concentration results in rapid, and in 15-20% cases - sudden death because of the respiratory paralysis. Some methods were elaborated for CO2 concentration determination in the air: method with barium hydrate by Subbotin-Nagorskiy, methods by Reberg-Vinokurov, Kalmikov, interferometrical method. The portable express method by Lunge-Zeckendorf modified by D.V. Prokhorov is the most widely used in the sanitary practice (see appendix 2). Appendix 2 Carbon dioxide determination in the air using the express method by Lunge-Cekkendorf, modified by D.V. Prokhorov The method is based on blowing the investigated air through the sodium carbonate (or ammonia) volumetric solution in presence of the phenol-phthalein. The Na2CO3+H2O+CO2=2NaHCO3 reaction takes place in this case. Pink in the alkaline medium, the phenol-phthalein is discoloured after the contact with CO2 (acid medium). The raw solution is prepared by dilution of 5.3 g chemically pure Na2CO3 into 100 ml of distilled water and 0.1% solution of phenol-phthalein is added to the raw solution. Before analysis the work solution is prepared by dilation of 2 ml raw solution to 10 ml by distilled water. The solution is poured into Drecsel’s bottle by Lunge-Zeckendorf method (fig. 11.1-а) or into Janet’s syringe in Prokhorov’s modification (fig. 11.1-b). In the first case the rubber syringe with valve or small aperture (hole) is connected with the long tube of Drecsel’s bottle with thin beak. The investigated air is blown though the solution by slow compression and fast release. The bottle is shaken up till the total absorption of CO2 from the air sample after each blowing. In the second case (Prokhorov’s modification) the total air volume is collected into the Janet’s syringe, filled with 10 ml of the work soda solution with phenol-phthalein and held with the cannula up, the syringe is also shaken up. The air volumes for discoloring of the solution are calculated. The air analysis is carried out indoor and outside (atmospheric air). The result is calculated by the inverse proportion under comparison of the used syringe volumes quantities and CO2 concentration in the atmospheric air (0.04%) and unknown СО2 concentration in the certain investigated indoor premise. For example, 10 syringes were used indoors and 50 - outdoors. CO2 concentration indoors = (0.04×50) : 10 = 0.2% CO2 maximum allowable concentration (MAC) of the indoors (premises of various purpose) is determined at the level 0.07-0.1%, in industrial premises where CO2 is accumulated during manufacture processes - 1-1.5%.  Fig.11.1-а. Device for determination of СО2 concentration by Lunge-Cekkendorf (а – rubber syringe for the air blowing with valve; б – Drecksel’s bottle with soda solution and phenol-phthalein)  Fig. 11.1-b. Janet’s syringe for determination of СО2 concentration by D.V. Prokhorov Appendix 3 Methods of determination and hygienic assessment of the air circulation and indoor ventilation The indoor air is considered pure if CO2 concentration does not exceed the maximum allowable concentrations – 0.07% (0.7‰) by Pettencofer or 0.1% (1.0‰) by Flugge. In accordance to this statement the required ventilation volume is calculated. The required ventilation volume is the volume of the fresh air, which is to be drawn inside so, that CO2 concentration does not exceed the allowable value. This volume is calculated using the following formula: V=  where: V – ventilation volume, m3/hour; К – volume of СО2, expired by one person per hour (in calm conditions 21.6 l/hour; while sleep – 16 l/hour; performing the job of different heaviness – 30-40 l/hour); n – the number of people inside; Р – СО2 maximum allowable concentration in pro mil (0.7 or 1.0‰); Р1 – СО2 concentration in the atmospheric air in pro mil (0.4‰). The calculation of the СО2 volume expired by one person per hour is based on the CO2 concentration in the expired air (4%), inspiration and expiration rate (under calm conditions – 18 inspirations per minute × 60 = 1080 per hour) and expired air volume – 0.5 l per one expiration, and this totals to: 1080 × 0,5 = 540 l/hour. Using the following proportion: 4 l – 100 l, х – 540 l, the expired CO2 volume may be calculated: х =  = 21.6 l/hourThe respiration rate, expired СО2 volume and required ventilation volume are increased during the physical activity in proportion to their heaviness and intensity. Required ventilation rate (air exchange rate) is the number, demonstrating how many times the indoor air has to be completely renewed by the ventilation so, that СО2 concentration does not exceed the maximum allowable concentration (MAC). Required ventilation rate (air exchange rate) is found by dividing the calculated required ventilation volume by the indoor cubature. Actual ventilation volume is found by determination of the ventilation source area and the speed of the air movement through it (e.g. transom, wicket). The air volume equal to the indoor cubage (cubature) is drawn inside through the wall perforations, windows slits and doors, and it must be added to the volume of the air, drawn through the ventilation. Actual ventilation rate (air exchange rate) is calculated by dividing the actual ventilation volume by the indoor cubage (cubature). The indoor air change efficiency may be determined comparing the required and actual volumes and ventilation rates. Appendix 4 The air ventilation rate standards for different premises
The required volume and ventilation rate are also assumed to be a scientific basis of residence area standards. Assuming, that the air volume equal to the room cubage (cubature) is drawn inside through the wall perforations, windows slits, and doors (the ventilation rate is ~ once per hour), and the average ceiling height is 3 m, the “normal” area for 1 person is:
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= 
= 12 m2/person;
= 24 m2/person.