In this video, the author tests the efficiency of various masks on the containment of aerosols. Have a watch and decide how effective your mask might be, when you also think about how much you touch it when you're wearing it, how many times you reuse the same mask etc.
It's worth also mentioning here that the UK Government has absolutely no scientific evidence masks work and the requirement to wear masks in the UK is Guidance only and not law - although the Government make's it sound as though it is by using convoluted language. Check for yourself on the UK Government website and you will see in the blue title strip the small words "guidance". Now you know this, ask yourself why you are being pressured everywhere you to go wear a mask. If you wear one regularly and for long periods of time what are the health and safety ramifications on you. Has your Employer done a risk assessment on the potential negative impact of mask wearing on your health (mental, emotional and psychological)? Consider the real implications of re-breathing dirty bacteria that collects inside the mask and why many people develop acne, headaches and feel sleepy when they are wearing one for long periods of time? Could it be that extended mask wearing may be causing damage to your body?