Laminar Airflow in Severe Asthma for Exacerbation Reduction

We will include 222 adults, half of whom will be given a TLA device that is working, and the other half will be given a device which has been inactivated (the filtering process will be switched off, although the participants will not be able to tell that this has occurred). Which participant receives the working or deactivated device will be decided by a random process and will be unknown to the researcher and the participant. An engineering team from the manufacturer will install the device in the participants' home at the beginning of the study and be available throughout the study period to deal with any queries. All participants will continue receiving their usual treatments. Participants will be in the study for 12 months, and will report their asthma attacks to the trial team whenever they occur during this period. In addition, they will visit the trial team 4 times (after 3, 6, 9 and 12 months) to assess their asthma control and quality of life. At the end of the trial, we will invite participants at each site to join a group discussion where researchers will explore the participant's thoughts about the TLA device. At the end of their participation in the trial, all participants who have used the device for more than 6 months, regardless of their initial study group, will be offered the opportunity to keep an active device in their home free of charge for a further four years.