This paper provides an overview of the HEAT (Healthy Environments for AthleTes) project, which aims to understand the impact of environmental conditions on athlete health and performance during major sporting events such as long-distance running, cycling, and triathlons. In collaboration with the SAFER (Strategies to reduce Adverse medical events For the ExerciseR) initiative, the HEAT project carried out a field campaign at the 2022 Comrades Marathon in the KwaZulu-Natal province of South Africa. The measurement campaign deployed seven weather stations, seven PM_2.5 monitors and one spore trap along the 90 km route to capture spatially representative measurements of complex micro-climates, allergenic aerospora, and particulate matter exposure. The results indicate that runners were exposed to moderate risk heat stress conditions. Novel findings from this initial campaign shows elevated and potentially harmful PM_2.5 levels at spectator areas, possibly coinciding with small fire events around the race day festivities. Our findings show values PM_2.5 levels over the WHO 24-h guidelines at all stations, while 2000 µg/m³ at two stations. However, the lack of an acute exposure standard means direct health impacts cannot be quantified in the context of a sport event. The HEAT project highlights important aspects of race day monitoring; regional scale climatology has an impact on the race day conditions, the microclimatic conditions (pollution and meteorology) are not necessarily captured by proximity instruments and direct environmental measurements are required to accurately capture conditions along the route.

Nitrogen oxides, particularly NO₂, are emitted through a variety of industrial and transport processes globally. The world’s continuous economic development, including in developing countries, results in an increasing concentration of those gases in the atmosphere. Yet, there is scant information on the current state and recent evolution of these atmospheric pollutants over a range of spatial and temporal scales, especially in Africa. This, in turn, hinders the assessment of the emissions and the evaluation of potential risks or impacts on societies and their economies, as well as on the environment. This study attempts to fill the gap by leveraging data from a Pandora-2S ground-based, column-integrating instrument located in Wakkerstroom in the Mpumalanga Province of South Africa and space-based remote sensing data obtained from the TROPOMI instrument onboard the ESA Sentinel-5P satellite. We compare these two spatially (horizontal) representative data sets using statistical tools to investigate the concentrations of emitted and transported NO₂ at this particular location, expecting that a significant positive correlation between the NO₂ tropospheric vertical column (TVC) data might justify using the TROPOMI data, available globally, as a proxy for tropospheric and boundary layer NO₂ concentrations over the Highveld of South Africa more generally. The data from the two instruments showed no significant difference between the interannual mean TVC-NO₂ in 2020 and 2021. The seasonal patterns for both instruments were different in 2020, but in 2021, both measured peak TVC-NO₂ concentrations in late winter (week 34). The instruments both detected higher TVC-NO₂ concentrations during transitions between seasons, particularly from winter to spring. The TVC-NO₂ concentrations measured in Wakkerstroom Mpumalanga are mostly contributed to by the emission sources in the low troposphere, such as biomass burning and emissions from local power stations.

The Comrades Marathon is South Africa’s – and the world’s – most recognised and largest ultra-marathon event, with over 15 000 participants from across the globe competing in the 89-km road running event each year. Historically, the event has been held before the start of austral winter (20 May – 17 June). However, in 2022, organisers of the race moved the event to 28 August, when austral spring commences. We explore the climate, in particular the Universal Thermal Comfort Index (UTCI), of past Comrades events (1980-2019) and compare these data to UTCI data of the new proposed date (28 August) for the same period. The climatology for May, June, July and August was determined to identify periods with the lowest risk for ‘strong’ to ‘very strong’ heat stress. Results show that participants’ risk of exposure to ‘strong’ heat stress and ‘very strong’ heat stress periods will be more likely if the event is held in August as compared to the original event dates. Therefore, it is concluded that mid-June to mid-July has the lowest risk of heat stress exposure along the route. Runners and organisers should be aware of the higher risk of exertional heat illness during the 2022 Comrades Marathon to ensure safe participation. Significance: The new proposed date for the Comrades Marathon will increase the risk of exposure to ‘strong’ and ‘very strong’ heat stress conditions, as defined by the Universal Thermal Comfort Index (UTCI). The UTCI indicates that mid-June to mid-July has the lowest risk of heat stress exposure at the three reference points along the route. Organisers should warn runners of the higher risk of exertional heat illness due to the possible exposure to high UTCI values or more unfavourable climatological conditions. Furthermore, runners should be informed of a variety of preventative strategies to ensure safe participation.

Water scarcity due to rainfall variability, and exacerbated by climate change, is prevalent in many regions of the world. Lack of precipitation and excessive water extraction contribute to the intensification of the problem. Among different mitigation measures, rain enhancement through cloud seeding could be a tool as part of a water management strategy to replenish ground water sources. However, implementation of this technology requires proper preliminary analysis of the available cloud data and specific meteorological conditions under which rainfall forms. The aim of this paper is to assess the potential of for rain enhancement in Minas Gerais State in Brazil. The paper focuses on analysis of multiyear climate reanalysis ERA-5, upper air sounding, weather radar and ground stations data. Analysis showed that, between 2000 and 2019, precipitation declined on average by 212 mm per annum or 21% compared to the long term climatological mean. The natural precipitation, however, remains sufficiently high to implement weather modification technology. Assuming an increase of 15–20% could be achieved on a catchment area basis, the increases would be significant and could offset the recently observed decline in natural precipitation. The methodology proposed in this study can be used as a baseline for similar analysis in other vulnerable regions of the world experiencing freshwater shortages or declines. Its shortcomings and uncertainties are also discussed.