In traffic congestions, the typical reaction of the drivers is to switch-on the recirculation mode of the vehicle's air conditioning system. In the summertime, in many cities with high air humidity and temperatures, people typically drive their cars in recirculation mode as well, to ensure the best cooling. However, the recirculation mode of the air in the cabin prevents O 2 from entering and leads to an increase in CO 2. In confined spaces (e.g., a vehicle cabin), the raised CO 2 concentration due to human exhalation and metabolism is associated with increased health symptoms, decreased concentration, and impaired performance. The paper presents an experimental study on the accumulation of carbon dioxide in a vehicle cabin from occupants breathing and metabolism. The concentration of CO 2 and O 2 were measured in terms of the number of occupants (1-4) in the car. The change in the indoor environmental parameters in the car cabin was also monitored. The results obtained show the increment of the CO 2 concentration at the expense of oxygen availability, together with the apparent impact of the number of people in the vehicle.

The study presents experiments, conducted with human subjects in an artificial cold chamber, assessing the influence of a cold environment on the temperature of the human body. Infrared thermography was applied as a non-invasive, contactless method for direct measurement of the temperature distribution of both clothed and uncovered parts of the body. Two subzero temperatures were applied and clothing ensembles with two different clothing insulation values were used to assess the effect of the clothing insulation of the torso on the temperature of clothed and uncovered parts of the body of the participants. The average temperature of the chest, back, upper arms, face and middle finger is presented and discussed in relation to the cold exposure duration and clothing insulation used. The results obtained showed the strong influence of the clothing insulation over the torso on skin and clothing temperatures of the body and overall cooling of the body in subzero temperatures.

The pyrolysis of wheat straw in order to produce biochar for soil amendment is a potential strategy for producing environmental friendly fertilizers capable of boosting soil fertility, increasing carbon storage, and lowering greenhouse gas emissions. However, straw biochar’s potential to influence these aspects may vary depending on its properties. Our study sought to investigate biochar from wheat straw from three different regions in Bulgaria. A specially designed set up was used for the biochar production. Three pyrolytic temperatures (300, 400, and 500 °C) were applied, resulting in nine biochar samples. The specific characteristics included moisture content, volatile substances content, ash content, fixed carbon content, and joint ash and carbon content, and they were determined for each sample. The chemical content, resulting in 17 chemical elements and compounds, was measured and analysed. The results obtained showed that the produced straw biochar has the potential to be used as a fertilizer and soil supplement.