The Actual Toxicity of Engine Exhaust Gases Emitted from Vehicles: The Development and Perspectives of Biological and Chemical Measurement Methods

[Image: see text] Most of the current studies on vehicle engine exhaust emissions are focused on qualitative and quantitative measurements. Approval tests for admitting vehicles to traffic and tests performed at vehicle inspection stations are limited to measuring the concentrations of individual compounds or selected groups of compounds. For vehicles with compression-ignition engines, the annual emission control comprises only an exhaust gas opacity test, performed with an opacimeter. This approach does not consider very harmful groups of compounds that determine the toxicity of exhaust gases but are not directly covered by the emission standards, such as polycyclic aromatic hydrocarbons and volatile organic compounds. Also, it does not provide a clear answer to the question of the actual toxicity of exhaust gases, understood as the harmful effect that a given substance causes on living organisms or biological processes. Studies on the actual toxicity of engine exhaust gases present a new area of interest, increasingly more discussed but still not approached in a comprehensive way. The studies include experiments using in vitro biological methods and chemical analyses of gas mixtures. In this Review, I present an overview of current research and a critical comparison of commonly used methods of testing engine exhaust emissions and methods that might supplement them in a significant manner. The development of in vitro biological methods, including methods of microscopic analysis of cells in the assessment of exhaust gas toxicity, provides an innovative approach to the problem of air pollution. This type of research presents the opportunity to indisputably answer the question of the actual toxicity of a given gas mixture and to make a new contribution to science in the field of molecular biology. Current data show that the survival of cells exposed to engine exhaust emissions from older generation vehicles is higher compared to that of newer generation vehicles.