Chronic obstructive pulmonary diseaseExposure to sunlight

Solar UVB is the primary source of vitamin D, so at higher latitudes, serum 25(OH)D levels are lowest in late winter or early spring. As a result, respiratory viral infections are most common in winter or spring1 2. Viral infections are frequently found associated with exacerbations of COPD3.

A study in Finland on hospitalization for the acute exacerbation phase of COPD found 62.8% of the treatment periods ending in death took place between December and May4. That period is the time when viral respiratory infection rates are highest1 2 5.

There is some additional evidence that UVB and vitamin D reduce the risk of COPD exacerbations from studies of occupation and COPD. Two studies reported that farmers had lower rates of COPD exacerbations.

One, a study in Ohio and North Carolina reported lower mortality rates for farmers6.

The other, for COPD hospitalizations in Denmark, reported lower rates for farmers7.

However, farmers in general have higher rates of COPD, likely due to occupational exposure to organic matter and chemicals8 9. Farmers generally have lower rates of lung cancer6 10 11, likely due to higher solar UVB doses and serum 25(OH)D levels. 

Page last edited: 06 May 2011


  1. Cannell, J. J. Vieth, R. Umhau, J. C. Holick, M. F. Grant, W. B. Madronich, S. Garland, C. F. Giovannucci, E. Epidemic influenza and vitamin D. Epidemiol Infect. 2006 Dec; 134 (6): 1129-40.
  2. Cannell, J. J. Zasloff, M. Garland, C. F. Scragg, R. Giovannucci, E. On the epidemiology of influenza. Virol J. 2008; 529.
  3. McManus, T. E. Marley, A. M. Baxter, N. Christie, S. N. O'Neill, H. J. Elborn, J. S. Coyle, P. V. Kidney, J. C. Respiratory viral infection in exacerbations of COPD. Respir Med. 2008 Nov; 102 (11): 1575-80.
  4. Kinnunen, T. Saynajakangas, O. Keistinen, T. Features of hospitalisations for acute exacerbation of COPD resulting in death. Monaldi Arch Chest Dis. 2007 Mar; 67 (1): 10-4.
  5. Moineddin, R. Nie, J. X. Domb, G. Leong, A. M. Upshur, R. E. Seasonality of primary care utilization for respiratory diseases in Ontario: a time-series analysis. BMC Health Serv Res. 2008; 8160.
  6. Blair, A. Sandler, D. P. Tarone, R. Lubin, J. Thomas, K. Hoppin, J. A. Samanic, C. Coble, J. Kamel, F. Knott, C. Dosemeci, M. Zahm, S. H. Lynch, C. F. Rothman, N. Alavanja, M. C. Mortality among participants in the agricultural health study. Ann Epidemiol. 2005 Apr; 15 (4): 279-85.
  7. Tuchsen, F. Hannerz, H. Social and occupational differences in chronic obstructive lung disease in Denmark 1981-1993. Am J Ind Med. 2000 Mar; 37 (3): 300-6.
  8. Linaker, C. Smedley, J. Respiratory illness in agricultural workers. Occup Med (Lond). 2002 Dec; 52 (8): 451-9.
  9. Monso, E. Riu, E. Radon, K. Magarolas, R. Danuser, B. Iversen, M. Morera, J. Nowak, D. Chronic obstructive pulmonary disease in never-smoking animal farmers working inside confinement buildings. Am J Ind Med. 2004 Oct; 46 (4): 357-62.
  10. Brownson, R. C. Reif, J. S. Chang, J. C. Davis, J. R. Cancer risks among Missouri farmers. Cancer. 1989 Dec 1; 64 (11): 2381-6.
  11. Pukkala, E. Martinsen, J. I. Lynge, E. Gunnarsdottir, H. K. Sparen, P. Tryggvadottir, L. Weiderpass, E. Kjaerheim, K. Occupation and cancer - follow-up of 15 million people in five Nordic countries. Acta Oncol. 2009; 48 (5): 646-790.