Cold winter increases the risk of new asthma

The study was based on over 2,500 children recruited in the Espoo cohort study, founded by Professor Jouni Jaakkola, since 1990. Their health has been monitored until the age of 27. By analyzing 315 recent cases of asthma, researchers aimed to understand how the conditions of a cold winter influence the occurrence of asthma.

Researchers compared the average winter temperatures during three winter months (December-February) before the onset of asthma, the year preceding these winter months, and the year following the onset of asthma.

The results indicated that each one-degree (°C) decrease in the average winter temperature predicted a seven percent increase in the risk of new asthma. Particularly noteworthy was that a cold winter with an average temperature below the climatological norm increased the risk of new asthma by a staggering 41 percent in the following year.

While previous studies have shown that cold air exacerbates asthma and increases respiratory symptoms, this research provides new insights into the idea that a cold winter can also increases the risk of developing new asthma.

Based on the results, Jaakkola predicts that the ongoing exceptionally cold winter will elevate the risk of new asthma cases in the coming year. However, researchers emphasize that asthma is a complex disease influenced by genetic, environmental, and lifestyle factors.

The study has been published in the Occupational and Environmental Medicine journal: Belachew AB, Rantala AK, Jaakkola MS, Hugg TT, Ruuhela R, Kukkonen J, Jaakkola JJK. Effect of cold winters on the risk of new asthma: a case-crossover study in Finland. Occup Environ Med. 2023 Nov 23;80(12):702-705. doi: 10.1136/oemed-2022-108682.