Healthy environments for athleTes (HEAT): environmental conditions along a 90 km ultra-marathon event, South Africa

Abstract

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.

Keywords: Aerospora; Climate change; Endurance events; Environmental impacts on Athletes; Heat stress; Southern Africa.

Fig. 1

Map of the deployment points along the route, each point is + -15 km apart. At each cut-off point, a station was located. In total 7 stations were deployed, with the first deployment at 15 km (Lynnfield Park)

Fig. 2

Instruments placed along the route. a The meteorological station and the PM_2.5 SidePak Monitor. b Burkard® spore trap, which was placed at Halfway point

Fig. 3

a Satellite imagery (©EUMETSAT 2022) of race day indicates mainly fine and dry conditions along the interior. The cold front south east of South Africa results in onshore flow along the escarpment and subsequent cloud formation. b Synoptic weather for 28 August indicates a weak pressure gradient between the passing cold front South East of the country and the easterly low over the interior. There was some onshore flow with light cloud development along the Durban coast. Westerly flow at 500 hPa is pronounced and would enhance cloud formation throughout the day along much of South Africa and along the race location (in both images indicated in red)

Fig. 4

Temperature and Relative Humidity at all stations along the route. The first record at each station starts when the first runner passes the station, and ends when the cut-off time stops runners at the point from running further. The total deployment time of each station is documented in Table 1

Fig. 5

Frequency distribution of wind speed and direction at each station for the time period that runners passed the station. Data was recorded at 1 min intervals, each station data was averaged over the period that the station was deployed, i.e. from the first runner that passed, until the cut-off was reached as detailed in Table 1. Measurements show the local, microclimate winds at each location and are subject to various influences, but represent the conditions runners typically experienced

Fig. 6

Derived wet-bulb globe temperature (WBGT) using Liljegren method. Low risk conditions occurred later in the day, runners could potentially be exposed to these conditions for 7 h

Fig. 7

PM_2.5 Concentration at all sites per hour is shown in the box and whisker which indicates the median, 25th and 75th percentiles of the raw data, including the outliers. A sudden drop in PM_2.5 at Pinetown at noon corresponded to a change in wind direction, also observed at an nearby SAAQIS air quality monitoring station

Fig. 8

Fungal spores and pollen count at the Halfway point. Most abundant fungal spores were Smuts (75 sp.g/m³), Cladosporium (53 sp.g/m³), Alternaria (26 sp.g/m³). Cyperaceae (5p.g/m³). Combretaceae (4p.g/m³) were the abundant pollen

Fig. 9

Fungal spores diurnally distribution pattern of airborne fungal spores (2:00am-12:00 pm)

Fig. 10

Pollen diurnally distribution pattern (2:00 am-12:00 pm). A maximum of Cyperaceae pollen (6 p.g/m³) was detected at 7:00 am