A recent study proposed the idea that damage to our DNA at the telomeres contributes to lung ageing, continuing damage and worsening COPD symptoms. Also that cigarette smoke increases and encourages such damage to the telomeres.
smoke
Telomeres are specialized structures at the ends of chromosomes within our DNA that protect it from deterioration and prevent fusing with nearby chromosomes. COPD has long been associated with accelerated lung aging and abnormal cell division. Telomeres shorten with each cell division, therefore the more the cell divides the less protection the DNA strands have.
In a newer study they investigated telomere dysfunction in lung airway cells from patients with COPD using lung aging mouse models exposed to cigarette smoke. They found that there was no difference in telomere length between control patients and COPD patients, which contradicts the previous study although they say that this could be due to a small sample size and will need to be repeated with a larger amount of samples.
With age they observed an increase in telomere dysfunction and that this was also increased with exposure to cigarette smoke. They found that the cigarette smoke accelerated the telomere dysfunction by increasing levels of reactive oxygen species (free radicals) and aided in the secretion of inflammatory cytokines.
As a result, the team highlighted that their findings suggest that telomeres are particularly susceptible to damage triggered by cigarette smoke, and that this may lead to an accelerated decline of lung function in both aging and COPD patients.  So whether you have COPD or have normal respiratory health, exposure to cigarette smoke will trigger telomere dysfunction, affecting the DNA within the cells and causing damage to the cells in your lungs. And thereby  reducing respiratory function in the elderly and worsening symptoms in COPD patients. This study suggests that the elderly and patients suffering from respiratory illness should not only stop smoking but also not be around other smokers in order to preserve their respiratory health.
References: http://copdnewstoday.com