Practical work 1
ASSESSMENT OF EXPOSURE TO HARMFUL SUBSTANCES CONTAINED IN THE AIR
The purpose of the work is to study the theoretical provisions on the regulation of the content of harmful substances in the air, compare the data on the variant of the concentration of substances with the maximum allowable and draw a conclusion about the compliance with the standards for the content of each of these substances.
To ensure human life, an air environment of a certain qualitative and quantitative composition is necessary. The normal gas composition of the air is as follows (%): nitrogen – 78.02; oxygen – 20.95; carbon dioxide – 0.03; argon, neon, krypton, xenon, radon, ozone, hydrogen – up to 0.94 in total. Real air, in addition, contains various impurities (dust, gases, vapors) that have a harmful effect on the human body.
The main physical characteristic of impurities in atmospheric air and indoor air is the mass concentration (mg) of a substance per unit volume (m 3 ) of air under normal meteorological conditions. Their influence on natural objects depends on the type, concentration of impurities and duration of exposure.
Rationing of the content of harmful substances (dust, gases, vapors, etc.) in the air is carried out according to the maximum permissible concentrations (MPC).
MPC – the maximum concentration of harmful substances in the air, referred to a certain averaging time, which, with periodic exposure or throughout a person’s life, does not have a harmful effect on him or the environment as a whole (including long-term consequences).
The content of harmful substances in the atmospheric air of populated areas is standardized according to GN 126.96.36.1998-03, and for the air of the working area of industrial premises – according to GN 2.25.1313-03.
The maximum allowable concentration of a pollutant in the atmospheric air of populated areas is a concentration that does not have a direct or indirect adverse effect on present or future generations throughout life, does not reduce a person’s working capacity, does not worsen his well-being and sanitary living conditions.
The standards are set in the form of maximum one-time and average daily MPCs with an indication of the hazard class and the limiting hazard indicator, which is the basis for setting the standard for a particular substance.
The limiting (determining) indicator of harmfulness characterizes the direction of the biological action of the substance: reflex and resorptive.
Reflex action – a reaction from the receptors of the upper respiratory tract: smell, irritation of the mucous membranes, breath holding, etc. These effects occur with short-term exposure to substances, so the reflex action underlies the establishment of maximum one-time MPC (20-30 min).
Resorptive action is understood as the possibility of developing general toxic, gonadotoxic, embryotoxic, mutagenic, carcinogenic and other effects, the occurrence of which depends not only on the concentration of the substance in the air, but also on the duration of inhalation. In order to prevent the development of a resorptive effect, an average daily MPC is set (as a maximum 24-hour and / or as an average over a long period – a year or more).
MPCmax is the main characteristic of the danger of a harmful substance, which is established to prevent the occurrence of human reflex reactions (smell, light sensitivity, etc.) during short-term exposure (no more than 30 minutes).
MPCs – established to prevent general toxic, carcinogenic, mutagenic and other effects of a harmful substance when exposed to more than 30 minutes.
The MPC of harmful substances in the air of the working area is such a concentration that, with daily exposure (but not more than 40 hours per week) during the entire working experience, cannot cause diseases or deviations in the state of human health detected by modern research methods during work or in the long term of the life of the present and subsequent generations.
1. Having received this workshop, write down the name and purpose of the work, study and outline the main theoretical issues on the regulation of the content of harmful substances, transfer the form of the table. 1.1.
2. Selecting the task option from the table. 1.3, fill in columns 1–3 of Table. 1.1.
3. Using the regulatory and technical documentation (Table 1.2), fill in columns 4–8 of Table. 1.1.
4. Compare the concentrations of the substance specified by the option (see Table 1.3) with the maximum allowable (see Table 1.2) and draw a conclusion about the compliance with the standards for the content of each of the substances in columns 9–11 of Table 1.1, i.e. < MPC , > MPC, = MPC, denoting compliance with the standards with a “+” sign, and non-compliance with a “-” sign.
5. Draw conclusions and show the report to the teacher.
In table. 1.2 shows the standard values of harmful substances in the air according to GN 2.25.1313-03 and GN 188.8.131.528-03.
In table. 1.3 given the initial data for analysis by options