The projection and identification of historical and future changes in climatic systems is crucial. This study aims to assess the performance of CMIP6 climate models and projections of precipitation and temperature variables over the Upper Blue Nile Basin (UBNB), Northwestern Ethiopia. The bias in the CMIP6 model data was adjusted using data from meteorological stations. Additionally, this study uses daily CMIP6 precipitation and temperature data under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios for the near (2015–2044), mid (2045–2074), and far (2075–2100) periods. Power transformation and distribution mapping bias correction techniques were used to adjust biases in precipitation and temperature data from seven CMIP6 models. To validate the model data against observed data, statistical evaluation techniques were employed. Mann–Kendall (MK) and Sen’s slope estimator were also performed to identify trends and magnitudes of variations in rainfall and temperature, respectively. The performance evaluation revealed that the INM-CM5-0 and INM-CM4-8 models performed best for precipitation and temperature, respectively. The precipitation projections in all agro-climatic zones under SSP1-2.6, SSP2-4.5, and SSP5-8.5 scenarios show a significant (p < 0.01) positive trend. The mean annual maximum temperature over UBNB is estimated to increase by 1.8 °C, 2.1 °C, and 2.8 °C under SSP1-2.6, SSP2-4.5, and SSP5-8.5 between 2015 and 2100, respectively. Similarly, the mean annually minimum temperature is estimated to increase by 1.5 °C, 2.1 °C, and 3.1 °C under SSP1-2.6, SSP2-4.5, and SSP5-8.5, respectively. These significant changes in climate variables are anticipated to alter the incidence and severity of extremes. Hence, communities should adopt various adaptation practices to mitigate the effects of rising temperatures.

A series of experiments was undertaken on an intercity train carriage aimed at providing a “proof of concept” for three methods in improving our understanding of airflow behaviour and the accompanied dispersion of exhaled droplets. The methods used included the following: measuring CO₂ concentrations as a proxy for exhaled breath, measuring the concentrations of different size fractions of aerosol particles released from a nebuliser, and visualising the flow patterns at cross-sections of the carriage by using a fog machine and lasers. Each experiment succeeded in providing practical insights into the risk of airborne transmission. For example, it was shown that the carriage is not well mixed over its length, however, it is likely to be well mixed along its height and width. A discussion of the suitability of the fresh air supply rates on UK train carriages is also provided, drawing on the CO₂ concentrations measured during these experiments.

Non-methane volatile organic compounds (NMVOCs) in the atmosphere have garnered considerable attention worldwide because of their significance in atmospheric chemistry and their usefulness in identifying emission sources and chemical sinks. Despite the importance of VOCs, their routine measurement in the UK and across Europe is somewhat limited, and as such, there is limited information available regarding their sources, particularly in sensitive locations such as densely populated urban areas. In this study, hourly NMVOC concentration data measured between January 2015 and December 2023 were analyzed across four monitoring sites spanning an urban-to-rural gradient in England. The Marylebone and Eltham sites showed significantly higher concentrations of alkanes, alkenes, and aromatic hydrocarbons compared to the rural sites of Chilbolton and Auchencorth, with highest recorded VOC values of 29.9 ± 9.1 and 15.3 ± 4.3 µg m⁻³, respectively. Ethane (C₂H₆) and propane (C₃H₈) showed their highest ozone formation potential (OFP) levels at Marylebone Road, with the contribution of ethane to ozone formation ranging from 4% in Eltham to 8% in Chilbolton. This indicates that the emissions from vehicles and industries have a greater impact on the reactivity of these compounds. The potential source contribution function (PSCF) showed that the Marylebone and Eltham sites are mainly impacted by local traffic sources, while Chilbolton and Auchencorth receive VOC emissions from wider geographical areas. The COVID-19 lockdowns caused significant reductions in VOC concentrations at urban sites, which resulted in total VOCs declining by 26% at Marylebone Road and 11% in Eltham, while rural sites remained unaffected. The study results demonstrate new insights into NMVOC long-term temporal patterns and source identification across different UK environments, with important implications for air quality management and emission control policies.