It is very important to reduce harmful emissions in rural areas. One of the ways is to replace old tractors and farm machinery with the modern, equipped with engines of the highest standards. However, the cost of such replacement is very high and not always acceptable, especially for smaller farmers, nevertheless, due to the needs of sustainable agriculture it should be kept up. This work focuses on exhaust harmful emission during a start-up of a diesel engine installed in a small agricultural tractor. Based on measurements and recorded data, calculations of exhaust gas emission were carried out. The results indicate that the engine starting process, and its initial temperature, have a considerable impact on the emissions during the analyzed operation period. The most important is cold start process which is responsible for most harmful pollutants emission during the initial period of engine work. The temperature of cold start is also noticeable for cold starts and for worm starts as well.

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The paper presents results of experimental studies concerning CO2 emission of S-4003 diesel engine Ursus C-360 at a variable fuel injection advance angle and opening pressure of injectors. Measurements were made on the dynamometric stand on the test bench. The engine operated according to the load characteristic at two characteristic rotational speeds i.e., at the maximum torque velocity (1600 rpm) and at the rated speed (2200 rpm). In each measurement point of load characteristics, CO2 concentration was measured in exhaust gases with the use of exhaust gases analyser M-488 Multigas Plus. For a more detailed analysis of the CO2 content in exhaust gases, additional change of O2 level emission was presented, which in the biggest amount combines elementary carbon included in fuel during combustion. The studies showed the CO2 content reduction in exhaust gases at the reduced (by 3º of crankshaft rotations) fuel injection advance angle in comparison to the nominal angle by 4.5% at the rotational speed of 1600 rpm and by 5.7% at the speed of 2200 rpm (the average values for all measurement points of load - brake horsepower of engine). Similarly, CO2 concentration decrease in exhaust gases of the investigated engine was reported for the increased (by 1.5 MPa) opening pressure of injectors in comparison to the nominal pressure, on average by 9.8% for the speed of the maximum rotational moment and by 4.5% for the rated speed.

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Our paper presents the problem of real hazards for products (edible or inedible) and animals identified as a result of border control in international road transport. A border control system used on the Polish part of the eastern border of the European Union was selected and some data were analyzed concerning the number of checks and shipments rejected due to the epidemiological risk. The data have been collected from annual control reports for Poland. It has been shown that the biggest biological threat comes from the border with Belarus (most shipments were rejected). It was noted that the proportion of imported shipments rejected on the borders had a very strongly positive correlation (correlation coefficients: 0.96 and 0.99).