There not enough evidence to show how effective using a face mask is to protect yourself againgst infectious dieases. While some people with asthma, wearing a face mask can make breathing difficult.
The use of face masks to protect against covid19 is not clear. Face masks may reduce the risk of spreading infection by catching some of the droplets when people cough. It may be sensible to wear one when you go out, especially if your asthma makes you cough normally. Home-made cloth masks, or scarves, are suitable for this - there is no need to use a hospital type mask. (And face masks like this must be worn correctly, changed frequently and removed properly to be effective.)
Because the evidence is so unclear, there is a range of recommendations at the moment. As more evidence becomes available, this advice is likely to be updated.
In Scotland, it’s recommended that people wear face coverings in enclosed spaces where it’s difficult to achieve social distancing, such as when using public transport. The guidance is to use a scarf, bandana, cloth or textile and not a medical grade face mask. You should wash your hands when you put on your covering or take it off. And after each use, wash it at 60C.
In England, the government’s advice that there is very little evidence of widespread benefits from the use of face masks outside clinical settings, is under review.
If you feel comfortable wearing a mask when you’re in a public place and it’s hard to keep 2m away from other people, and you choose to wear a mask, please use a cloth covering and not a mask designed for clinical use.