According to the US-based study noted above, researchers followed 3099 patients for 20 years. Those with active asthma were 10 times more likely to develop symptoms of chronic bronchitis and 17 times more likely to be diagnosed with emphysema (COPD) than those without asthma.
Biomass fuel made from wood, charcoal, and other vegetable matter and animal dung is a major risk factor for the development of COPD. About 3 billion people worldwide are exposed to smoke from biomass fuel compared with 1.01 billion people who smoke tobacco.
In rural India a retrospective analysis of more than 300 patients with obstructive airway disease showed that 75% of patients with poorly treated asthma, who had received oral bronchodilator drugs alone for a long period, had symptoms characteristic of COPD.
The association of COPD with farming has been predominately recorded in atopic farmers (from positive skin prick tests to common aero-allergens), suggesting that atopic farmers might have increased susceptibility to COPD.
Asthma and COPD can co-exist in one patient.
'Consultation Strategy for Services for COPD in England', 'Department of Health', Gateway number 11943, Copyright Crown, 23, Feb, 2010
'Chronic obstructive pulmonary disease in non-smokers; Review', Sundeep S Salvi, Peter J. Barnes, 'The Lancet': (2009) Vol. 374; p733-743