Asthmatics should take extra precautions over the Covid-19 pandemic, a charity said yesterday.Liz Boden, the president of asthma group Open Airways, said people with the condition should use their preventer inhalers twice a day to keep it under control.She added: “These inhalers can take up to two weeks to start working, so don’t wait until you have the flu and say ‘I should start’ — if you’re not taking it every day, you must start.”The Centres for Disease Control have warned that people with asthma may be at higher risk of suffering severe effects if they are hit by Covid-19.The CDC website said that the virus could affect the respiratory system and lead to asthma attacks, pneumonia or acute respiratory disease in people with asthma.The World Health Organisation also warned that people with pre-existing conditions such as asthma were more vulnerable to the illness.Ms Boden said that asthmatics should take their preventer inhaler every morning and every evening to keep their lungs at their peak.She explained: “So many people take it only when they get an asthma attack.“We want them to take it every day to keep the asthma away and keep their airways calm, so if you do get the virus, your lungs are stronger. If people get their asthma under control, they should have the same risk factor as everybody else.”Ms Boden said that people in self-isolation or under mandatory quarantine should avoid using aerosol sprays indoors.People in self-isolation should get as much fresh air as they can by leaving windows open and spend as much time outdoors as possible, but still observe social distancing.Ms Boden said: “If you’ve got a garden or a yard then spend some time outside, but make sure you don’t leave your home and that you distance yourself from others as much as you can.“If you’re self-quarantining, then by all means stay indoors, but fresh air is the best thing for your lungs.” Ms Boden added: “I had somebody call me from Miami who’s a patient and she was saying ‘please, what do I have to do?’“It’s the same recommendations as everybody else, self-isolate, keep your hands away from your face and wash your hands.”• UPDATE: This article was amended to make clear that asthmatics should use their preventer inhalers twice a day to keep it under control