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Atmosphere pollution with noxious gaseous trace contaminants exhaled by man in an enclosure was investigated as a function of free volume per man. The parameter was shown to depend on the environmental conditions: with increase in free volume the total level of atmosphere pollution decreased, being proportional to the concentration of gaseous trace contaminants in the exhaled air. Experimental curves of accumulation of gaseous chemicals exhaled by man were built.

The purpose of the present investigation was to determine hygienic relevance of microbial degradation of polymers in an enclosed environment. Experiments were carried out to study the growth and development of microorganisms--molds and bacteria--on polymers. It was found that the process may be accompanied by the formation of volatile toxic substances, i.e. biodegradation products resulting from microbial decomposition of polymer components. Polymer ingredients are the major factor that determines the qualitative and quantitative composition of volatile substances. The accumulation of these substances on polymers leads to the deterioration of their sanitary-chemical properties and consequently to the contamination of the environment. It is shown that the basic products of biodegradation of polyurethane foam are ethanol and acetaldehyde and those of polyvinyl chloride plates, isooctanol (2-ethyl hexanol). The environmental parameters affect the microbial activity and therefore the rate of biodegradation processes.

Immunological reactivity of P. I. Klimuk and V. I. Sevastyanov was studied before and after their 63-day flight aboard the orbital station Salyut-4. The study used the methods to assay reactivity of T- and B-lymphocytes (PHA-blast-transformation, nonspecific formation of rosettes with sheep red blood cells, immunofluorescence to identify cells carrying immunoglobulin receptors on their surface, serum level of immunoglobulins as a function of Becells). Sensitization of the human body to allergenes of representatives of normal automicroflora of Staphylococcus, Streptococcus, Proteus and E. coli was examined. Specific immunological reactivity which was marked on the 2nd day and tended to return to normal on the 7th day postflight as well as a significant decrease of IgA were noted. Postflight P. I. Klimuk showed sensitization to allergens of Staphylococcus and Streptococcus. Results of immunological examinations of the first and second expeditions aboard the orbital station Salyut-4 were compared.

The Salyut-7 cabin environment was investigated with respect to the chemical, biological and physical factors. The gas composition was measured qualitatively and quantitatively. This determination showed a higher content of acetone and acetaldehyde when the cosmonauts worked on various trainers and unloaded the Progress cargo vehicles. The time-course study of the toxic impurities indicated that the increase in their content was transient (no more than 4 h). The microbial content was lower than in the Salyut-6 cabin environment. The study did not show a correlation between the microbial content in the environment and the time the prime crew remained onboard. There was a correlation between the microbial content, temperature variations, and conduct of certain experiments. On the whole, the Salyut-7 cabin environment was normal for the life and work of the crewmembers.

The paper presents brief information on the Apollo-Soyuz test mission, its program biomedical investigations to be carried out in flight and specific medical aspects. It discusses the main tasks of the joint US-USSR experiments and Soviet experiments. It gives and analyzes preliminary results of medical monitoring and postflight examinations of the crew members.

The environmental control system using superoxides, sillicagels or synthetic ceolites is capable of purifying the atmosphere from microorganisms. The air conditioning system is another means for air purification from microorganisms. The possibility of microbial build-up and multiplication in the atmospheric condensate makes it necessary to assume that an air conditioning system may contribute to the transfer of conditionally pathogenic microorganisms in a space cabin. The reliability of a life support system may degrade due to an accumulation of microorganisms in its components. Further extensive studies are needed to clarify this problem.

The Soyuz-22 space cabin atmosphere was studied for volatile organic trace contaminants. By gas chromatography the following constituents were identified: methane, ethane, heptane, methanol, ethanol, n-propanol, acetaldehyde, acetone, ethyl benzene. Except for acetone, concentrations of the above compounds were close to the values determined in the mock-up experiments.

The 63-day flight of cosmonauts P. I. Klimuk and V. I. Sevastyanov onboard the orbital station Salyut-4 has shown that man can well adapt to weightlessness and carry out diverse and intensive activities in the weightless state. Weightlessness effects on the human body may be both direct and indirect. The direct effects include reversal of deformations and mechanical tensions in tissue structures, change in the afferent impulsation from receptor zones reacting to the gravity effect, blood redistribution, disturbance in the function of sensory system. The indirect effects of weightlessness are associated with an unusual environment and unusual conditions of work rest, food and water consumption, etc. In the course of flight the human body adapts itself to the new environment; this is assured by self-regulation of physiological functions aimed at the maintenance of a constant level of vitally important parameters. Human adaptation to the weightless state can be subdivided into two periods: 1) period of adaptive rearrangement and 2) period of relative stabilization. The first period includes a rearrangement of functions and regulatory systems of the body. The second period can be defined as attainment of an intersystem homeostasis in the human body and a relatively stable equilibrium of the body with the environment. Incomplete adaptive reactions in shorter flights, e. g. during the first expedition of the orbital station Salyut-4 (G. M. Grechko, A. A. Gubarev), may be one of the factors responsible for a less favourable development of postflight readaptation. Thus, the most important purpose of the medical monitoring and prediction in prolonged space missions is to determine how complete or incomplete these adaptive reactions are. Relative stabilization can be reached, as a rule, after a 1.5 month exposure to weightlessness. However, this time period is rather relative since it depends on the characteristic features of the human body. The results of medical investigations carried out during and after the 63-day flight demonstrated no changes that could prevent from a further increase in the duration of future space missions.

On the basis of their findings and the data published in the literature the authors review the main results of investigations related to the hygienic maintenance of manned space flights. The paper presents the major problems in this field that need to be resolved in order to maintain adequate environments in space cabins.

This paper discusses various aspects of space vehicle habitability and life support systems. It describes variations in the chemical and microbial composition of an enclosed atmosphere during prolonged real and simulated flights. The paper gives a detailed description of life support systems and environmental investigations onboard the Mir station. It also outlines the development of space vehicle habitability and life support systems as related to future flights.

The concept of biological compatibility of men can be defined as a phenomenon which includes an effect (that might be favorable or unfavorable) of one individuum on the other via trace amounts of chemicals released into their environment and micro-organisms. The paper presents the main results of studies of biological compatibility of crewmembers of space vehicles and outlines possible directions of research to be carried out in this area.