Declan Rice and Mark Noble were pictured taking temperature tests prior to West Ham training on Wednesday.
The England international and Hammers captain both appeared to be blowing into a 'peak flow meter' in the car park with a member of the team's medical staff on hand to guide them through the process.
The plastic instrument measures how quickly you can blow air out of your lungs and the players would have been required to blow as hard as possible into the handheld tube.
Hammers captain Mark Noble was also pictured blowing into the small plastic tube
A reading can show whether the airways have constricted, which could be a sign of COVID-19.