Goal: to learn the parameters of the microclimate in the workplace, affecting health and human performance, methods and devices for their measurement.

Questions:

1. The main parameters of microclimate.

2. The devices and methods of measurement of microclimate parameters in the workplace.

3. Measures for the normalization of the status of air environment of industrial premises.

The health, its performance largely depend on the microclimate in the workplace. Without the ability to effectively influence flowing in the atmosphere of climate-forming processes, people have quality management systems factors of air environment in industrial premises.

The microclimate of industrial premises is the climate of the internal environment of the premises, which is determined jointly acting on the human body temperature (t, ^aboutC), relative humidity (j, %) and speed of air movement (V, m/s), as well as temperature surrounding surfaces (the intensity of thermal radiation (I, W/m²)).

Relative humidity is the ratio of the actual amount of water vapor in the air at a given temperature D(g/m³) the amount of water vapor, permeating the air at this temperature, D₀(g/m³):

j= ×100%.

(GOST 12.1.005 "General sanitary-hygienic requirements for working zone air").

The requirements of this state standard established for work zones – spaces in height to 2 m above the floor or platform, where are places of constant and temporary stay running. Consider a permanent workplace, which is more 50% working time (or more 2 hours continuously). If the work is carried out in different points of the working area, a permanent workplace is all the working area.

If in the workplace there are various sources of heat, temperature which exceeds the temperature of the human body, the heat spontaneously passes from them to a less heated body, ie. to person. Known, that there are three fundamentally different basic ways of heat propagation: the thermal conductivity, convection and thermal radiation.

The thermal conductivity represents the heat transfer due to chaotic (heat) movement of microparticles (atoms, molecules or electrons), direct contact with each other. Convection is the heat transfer due to the movement and the movement of macroscopic amounts of gas or liquid. Thermal radiation is the process of propagation of electromagnetic waves with different wavelength, due to thermal movement of atoms or molecules of the radiating body. In real conditions, heat is transferred not any one of the above methods, and combined.

Heat, entering the production room from various sources, affects the temperature of the air in it. In industrial premises with a high heat approximately 2/3 heat is supplied by radiation, and almost all the remainder is accounted for by the convection. The source of thermal radiation in industrial environments are the heated surface.

People in the labor process is constantly in a state of thermal interaction with the environment. For the normal course of physiological processes in the human body requires the maintenance of practically constant temperature of its internal organs (approximately 36,6⁰C). The ability of the human organism to maintain a constant temperature is called thermoregulation. Thermoregulation is achieved by dissipation of heat produced by the body in the process of life in the surrounding area.

Heat transfer from human body to the environment occurs in the following ways: as a result of heat conduction through clothing (Q_t); convection body (Q_to), radiation to surrounding surfaces (Q_and), moisture evaporation from the skin surface (Q_es), and due to the heating of the expired air (Q_in), ie:

Q_common = Q_t + Q_to + Q_and + Q_es + Q_in.

The equation is called the heat balance equation. The contribution of the above mentioned ways of heat transfer is variable and depends on the parameters of microclimate in industrial premises, as well as temperature surrounding surfaces (walls, ceiling, equipment, etc.). The main share in the process of removing heat from the human body (order 90% the total number of heat) make radiation, convection and evaporation.

Normal thermal state in the fulfilment of any category of severity is achieved by compliance with the thermal balance, the equation given above. Consider, what is the impact of the main parameters of microclimate on the heat transfer from the human body into the environment.

The effect of ambient temperature on the human body is primarily due to constriction or vasodilation of the skin. Under the action of low temperatures the blood vessels of the skin constrict, resulting in slowing down the blood flow to the body surface and decreases the heat loss from the body surface through convection and radiation. At high ambient temperatures the reverse is the case: due to the expansion of blood vessels of the skin and increase blood flow significantly increases the heat transfer to the environment.

High humidity (j>85%) impedes heat exchange between human body and external environment due to reduced moisture evaporation from the skin surface, and low humidity (j<20%) leads to drying of the mucous membranes of the respiratory tract. The movement of air in the production area improves the heat exchange between the human body and the external environment, but excessive air speed (drafts) increases the likelihood of colds.

Permanent deviation from the normal parameters of microclimate leads to overheating or overcooling of the human body and associated negative consequences: in case of overheating – sweating, the increased heart rate and breathing, severe weakness, dizziness, cramps, and in severe cases – the occurrence of heat stroke. Occur with colds colds, chronic inflammation of the joints, muscles etc.

Factors, influencing the microclimate, can be divided into two groups: unregulated (the complex of climatic factors of the area) and adjustable (the features and quality of construction of buildings and structures, the intensity of thermal radiation from heaters, the ventilation rate, the number of people and animals in the room, etc.). To maintain the parameters of the air environment of the working areas within the limits of hygiene norms and the exceptions listed above, the negative consequences of the crucial belongs to the second group of factors.

GOST 12.1.005 determined the optimal and allowable microclimatic conditions.

Optimal microclimatic conditions the combination of microclimate parameters, which in long-term and systematic exposure of humans to ensure preservation of normal function and the thermal state of the body without pressure of mechanisms of thermoregulation. In this case there is thermal comfort (the state of satisfaction of the external environment), provides a high level of efficiency. Such conditions are preferred in the workplace.

Allowable microclimatic conditions the combination of microclimate parameters, that the sustained and systematic impact on a person can cause transient and quickly normalizadas changes in the functional and thermal state of the body and stress mechanisms of thermoregulation, not beyond the physiological adaptive capacity of. This does not violate the condition, possible but uncomfortable reflecting thermal sensation, deterioration of health and reduced efficiency.

From the table 1.1 see, the parameters of the microclimate of industrial premises depend on the severity of works and period of the year (it is considered a warm period with daily average outdoor temperature above 10⁰ With, cold – with temperature 10⁰ C and below). The optimum parameters of microclimate applies to the entire working area of industrial premises without separating jobs to permanent and not permanent.

Table 1.1