Slightly dangerous.

By character of influence they divided into 6 groups:

I. toxic – inducing poisoning of the whole organism (carbon oxide, lead, mercury);

II. irritating – inducing irritating of respiratory tract and mucous shell (chlorine, acetone, ozone);

III. sensitising – influencing as allergen (formaldehyde, various lacquers, solvents);

IV. carcinogenic – inducing cancer (nickel and its compounds, chrome oxide, asbestos);

V. gene-mutating – changing heredity information (lead, manganese, radioactive substances);

VI. influencing on reproductive function (mercury, lead, manganese, radioactive substances).

The influence of harmful substances gets significantly increased under high temperature, noise and vibration.

One of the most important tasks of prophylaxis of occupational diseases is a control of air conditions inside working apartment. The purpose of the investigation is a qualitative detection and quantitative definition of harmful substances, which is contaminating the air in volume under consideration, and to compare the results with permissible concentrations (Tab.1). Referencing to legislation and state standard ГОСТ 12.1.005-88 (ССБТ. Общие санитарно-гигиенические требования к воздуху рабочей зоны) contents of harmful in the air of the work zone should not exceed limits of acceptable concentration of harmful substances.

Limits of acceptable concentration (LAC) of harmful substances in the air of the work zone determine the concentration which during every workday 8 hours (or other), except days off, up to 40 hours per week and while the whole length of service can not induce disease or be injurious to health what can be detected by modern methods of investigation carried out on working or separate terms of living of today’s and future generations.

Harmful substances are divided into substances of unidirectional and multidirectional action.

If there are some multidirectional harmful substances simultaneously being in the air of the work zone then concentration of everyone shouldn’t exceed corresponding LAC.

When some unidirectional harmful substances simultaneously are in the air of the work zone there should be the ratio between their concentrations C (C₁, C₂, … C_N) and their LAC (LAC₁, LAC₂, … LAC_N) satisfied:

Harmful substances can be present in the air of the work zone as a gas, vapour, drop of a liquid and small particles of a solid substance.

There is a continuous and periodical control of harmful substances contents carried out.

Continuous control is accomplished for harmful substances of 1 class of danger and foresees application of automatic recorder systems to indicate exceeding of LAC level by sound or light signal.

Periodical control is accomplished for harmful substances of 2, 3, 4 classes of danger and foresees measuring of concentration in defined periods.

Sensitivity of instruments and methods for control shouldn’t be less 0.5 of LAC level of harmful substance in taken air sample, and in blowing air – 0.3 of LAC level; error shouldn’t exceed ±25% of determined value.

Concentration of harmful substance in the air of the work zone is to be taken to normal conditions:

- Temperature 20°C (or 293K);

- Atmospheric pressure 760 millimetres of mercury column (or 101.3 kPa);

- Air humidity 50%.

Methods and means for sanitary and chemical analysis of the air are divided into three basic groups:

– laboratory;

– express;

– automatic.

There are over 200 various methods for determining harmful agents in the air of work zone, grounded on physical, chemical and biological processes.

Clear dry atmospheric air consists of oxygen (20.96%), nitrogen (78.06%), carbon dioxide (0.03…0.04%) and inert gases. In working apartments the content of the air may change.

Frequently in the air of the working apartment carbon dioxide and carbon oxide are of higher level, so as another mixtures that are widely used in civil aviation. They are fuels, lubricating oils and special aviation liquids, which are the harmful substances for human beings. In aircraft cabins chemical vapours from synthetic materials of cabin’s interior, varnish-painted covering, fuels-lubricating vapours, hydraulic and special aviation liquids’ vapours may enter in cabins during the flight and during the maintenance in airports.

Entering the working apartment most of these substances impacts on human organism. These substances are called harmful. In accordance with standard All-Union state standard (ГОСТ 12.1.007-76) "Harmful substances. A Classification and general requirements of safety" harmful substances are divided by their influence degree on human body on four classes of danger: 1) extraordinarily dangerous; 2) high dangerous; 3) moderately dangerous; 4) slightly dangerous.

One of the most important tasks of prophylaxis of occupational diseases is a control of air conditions inside working apartment. The purpose of the investigation is a qualitative detection and quantitative definition of harmful substances, which is contaminating the air in volume under consideration, and to compare the results with permissible concentrations (Tab.3).

Different methods are used for measuring of concentrations of harmful substances in the air and they are divided on two groups: laboratory and express methods.

Laboratory methods are more accurate and they need for more long execution and require from the workers a special qualification. Among the laboratory methods are following spectrophotometry, chromatography, polarography, potentiometry, and spectroscope.

Express methods are applied during short time duration, but they are less accurate. They are grounded on chemical reactions that are consequent with change of colour. Among the express methods are following colorimetry and linear colorimetry.

Colorimeter uses the reactive papers for detection of harmful substances in the air, which would coloured under the impact of these harmful substances. Presence of the harmful substance and its concentration are defined by length of coloured area and its intensity.

Linear colorimetry is grounded on coloured reaction between considered substances and indicator in form of powder that is applied on surface of solid absorbent inside small narrow glass tube. If an air that is needed to be analysed pass through this tube, the powder would be coloured on some length of the indicator layer. For particular limits of concentrations the linear relationship exists, that means a quantity of substance accords to 1 mm of coloured length, so a proportional coefficient may be used for assessment of the concentration.

Ventilation is a widespread means, which is used for creation of the proper sanitary-hygienic meteorological conditions in production apartments. Assessment of the ventilation is provided on ground of sanitary rules (norms) of design of the industrial plants and facilities. At working apartments, where one worker accounts for 20 m³ of the volume or less, the ventilation must be provided and carry the air not less than 30 m³/h for one person. If one worker accounts for over 20 m³ but not more than 40 m³ of the apartment volume, the ventilation must carry the air not less than 20 m³/h for one person.

Дата добавления: 2015-11-16