Hot or cold – impact on asthma and COPD

Airways Disorders Network

Asthma & COPD Section

Many of us may have experienced the extreme weather and climate patterns in the past year, depending on the region in which we live. These extreme weather changes are not unusual, but their recent occurrences may have been especially impactful on our patients.

Earlier works investigating effects of temperature and humidity changes on the airway in patients with asthma are insightful (Strauss, et al. 1978). Heat can irritate asthmatic airways that are already hyperreactive. Cold air can remove airway moisture. Similar mechanisms with warm/hot air can affect airway inflammation in COPD. In addition, poor air quality often occurs during extreme heat events and can affect patients with COPD.

Seasonal variation in COPD exacerbations was demonstrated by the TORCH study, where a two-fold increase in COPD exacerbations and hospitalizations was noted during the winter months in both northern and southern regions of the world. This trend was not observed in tropical countries with average annual temperatures of >18 °C (64 °F). Factors accounting for this variation may include greater risk of viral infections, increased host susceptibility, and more time spent indoors, along with impact of temperature variation on lung function (Jenkins, et al. 2012). This effect was accompanied by variation in the treatment choices with antibiotics alone or in combination with steroids. A trend towards combined antibiotics and steroids was noted during winters.

Ideal conditions for patients with COPD to minimize risk for exacerbation would be home humidity between 30% and 50% with indoor temperature of 21°C at least 9 hours per day in living areas (Osman, et al. 2008).

Outdoor activities during extreme temperatures should be avoided. Air conditioning and/or humidifiers can be helpful in modifying influences.

Maria Azhar, MD

Section Fellow-in-Training

Richard George Barbers, MD, FCCP

Section Chair

References

Jenkins CR, et al. Seasonality and determinants of moderate and severe COPD exacerbations in the TORCH study. Eur Respir J. 2012;39(1):38-45.

Osman LM, et al. Home warmth and health status of COPD patients. Eur J Public Health. 2008;18(4):399-405.

Strauss RH, et al. Influence of heat and humidity on the airway obstruction induced by exercise in asthma. J Clin Invest. 1978;61(2):433-40.