 Sensors installed by the Stockholm Environment Institute and the UN Environmental Programme are now in place in 12 stadiums and sports facilities in Kenya, Ethiopia, Senegal, Cameroon, Tanzania and Zambia. Dr Osano says they can help detect the key offender. We are particularly looking at an air pollutant called fine particulate matter, which is a pollutant that you cannot see with your naked eye, but which, if an athlete breathes, it really affects their health.