According to a study published in Indoor Air, The International Journal of Indoor Environment and Health, children in Sweden who slept in bedrooms with soft polyvinyl chloride (PVC) flooring were more likely to develop asthma during a 10-year research period compared with children living without the flooring material in their homes.

The study, which was conducted by researchers at the Department of Health Sciences, Karlstad University, Sweden also found indications that PVC flooring in the parents’ bedrooms led to stronger associations with new cases of asthma, which, researchers say, indicates that prenatal exposure to PVC flooring is a significant factor.

According to Carl-Gustaf Bornehag, author of the study, researchers began in 2000 by giving more than questionnaires to the parents and guardians of more than 14,000 children, ages 1 to 5 throughout Värmland, Sweden.

“In this baseline questionnaire we screened for health in the family, lifestyles, building characteristics, etc.,” Bornehag told Science Daily Magazine. “In 2005 we made a first 5-year follow up study and 2010 we made a second 10-year follow up, i.e., the data for the current study. The major interest in the follow up studies was to identify children that had developed asthma and other allergic diseases during the period after the baseline investigation.”

PVC is used in more than 30% of the Swedish bedrooms. According to study results, soft PVC includes phthalates that normally are released into the environment, many of which consist of industrial chemicals with endocrine-disrupting properties that researches say may lead to several chronic disorders, such as asthma, eczema, and severe allergies.