This research compares the nitrogen monoxide and methane exhaust emissions produced by the engines of two conventional chainsaws (a professional and an amateur one) to those produced by a catalytic. For all the three types of chainsaws, measurements were taken under the following three different functional modes: (a) normal conditions with respect to infrequent acceleration, (b) normal conditions, (c) use of high-quality motor oil with a clean filter. The experiment was extended much further by considering measurements of nitrogen monoxide and methane concentrations for all the three types of chainsaws, in respect to four additional operation forms. More specifically, the emissions were measured (a) under normal conditions, (b) under the application of frequent acceleration, (c) with the use of poor-quality motor oil and (d) with chainsaws using impure filters. The experiments and data collection were performed in the forest under “real conditions.” Measurements conducted under real conditions were named “control” measurements and were used for future comparisons. The authors used a portable analyzer (Dräger X-am 5000 a Dräger Sensor XXSNO and a CatEx 125 PRCH4) for the measurement of exhaust emissions. The said analyzer can measure the concentrations of exhaust gas components online, while the engine is running under field conditions. In this paper, we have been employed fuzzy sets and fuzzy Chi-square tests in order to model air pollution produced by each type of chainsaw under each type of operation condition. The overall conclusion is that the catalytic chainsaw is the most environmentally friendly.