Many people with chronic lung disease have disease flare-ups. It was previously believed that these were mainly caused by bacteria but recent evidence suggests that viruses could be an important trigger. This study will recruit volunteers with chronic lung disease and take samples both when well (at baseline) and during flare-ups (exacerbations) to better understand the role of viruses in triggering exacerbations and also how the immune response is affected. The researchers will follow the volunteers\' progress for up to two years. Whenever they get unwell they will take some samples (nose swabs, finger prick testing, phlegm sample) and post them to the researchers. Then, they will come in for a visit for more samples (blood tests, further swabs) and a review.