A report suggests that changes in humidity and temperature may trigger asthma among kids.
Published in the journal Annals of Allergy, Asthma and Immunology, the report says that such weather changes have been found to result in a rise in Emergency Department (ED) visits for pediatric asthma exacerbations.
"We found a strong relationship between temperature and humidity fluctuations with pediatric asthma exacerbations, but not barometric pressure," said Dr. Nana A. Mireku, an allergist at Dallas Allergy Immunology private practice in Dallas, formerly at Children's Hospital of Michigan, Wayne State University School of Medicine, Detroit.
"To our knowledge, this is the first study that demonstrated these correlations after controlling for levels of airborne pollutants and common aeroallergens.
"Our study is also one of the few to examine the possibility that the weather one or two days before the asthma exacerbation may be as important as that on the day of admission, as the additional ED visits occur one to two days after the fluctuation," she added.
The authors of the report write that patients experiencing an asthma attack often complain that weather fluctuations are a major trigger.
Dr. Mireku said: "the latest National Institutes of Health guidelines list 'change in weather' as a possible precipitating factor for asthma, but no previous studies have really examined this potential trigger in a rigorous fashion."
According to the report, the retrospective 2-year study was performed at a large urban hospital of 25,401 children visiting the ED for an asthma exacerbation.
The researchers collected data on climactic factors, pollutants and aeroallergens on a daily basis.
They used time series analysis to evaluate the relationship of daily or between-day changes in climactic factors and asthma ED visits, controlling for seasonality, air pollution and aeroallergen exposure.
The effects of climactic factors were evaluated on the day of admission and up to five days before admission.
The researchers found that a 10 percent daily increase in humidity on a day or two before admission was associated with approximately one additional ED visit for asthma.
The authors write that between-day changes in humidity from two to three days prior to admission were also associated with more ED visits.
Daily changes in temperature on the day of or the day before admission increased ED visits, with a 10 degree F increase being association with 1.8 additional visits.
"Asthma is the most common chronic illness in childhood. Allergists have long known that weather conditions such as extremely dry, wet or windy weather can affect asthma symptoms. This study further defines the role of temperature and humidity on children's asthma and confirms the importance of working with patients to identify the source of their symptoms and develop treatment plans that help prevent them," said allergist Richard G. Gower, president of the American College of Allergy, Asthma and Immunology (ACAAI).