Medway Asthma Self-Help (MASH) Medway Asthma Self Help (MASH) is a small charity that helps the people and families of Medway with asthma information, advice and support. We run asthma advice sessions with an asthma nurse on Friday afternoons and our monthly allergy testing session is for people with asthma aged 5 years and over (all appointments must be pre-booked). Our doors are open to everyone and all our services are free.