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Harmful Effect of Indoor Formaldehyde on Atopic Dermatitis in Children: A Longitudinal Study
Young Min Kim1,2, Jihyun Kim1,2, Seoung Chul Ha3
1Environmental Health Center for Atopic Diseases, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
Insights
Indoor formaldehyde exposure can worsen atopic dermatitis (AD) symptoms in children, especially during warmer months. Reducing exposure to formaldehyde, even at permissible levels, may help manage AD in kids.
Area of Science:
- Environmental Health
- Dermatology
- Pediatrics
Background:
- Limited evidence links indoor formaldehyde exposure to atopic dermatitis (AD) in humans.
- Atopic dermatitis is a common inflammatory skin condition in children.
Purpose of the Study:
- To investigate the longitudinal association between indoor formaldehyde levels and AD symptoms in children.
- To determine if common household formaldehyde levels impact AD severity.
Main Methods:
- A longitudinal study followed 55 children with moderate-to-severe AD for one year.
- Daily measurements of indoor formaldehyde levels and AD symptoms were recorded.
- Generalized linear mixed models analyzed the data, with subgroup analyses by demographics and environmental factors.
Main Results:
- Higher formaldehyde levels correlated with parental smoking, higher temperatures (>25.5°C), and elevated relative humidity (>60%).
- A 10 ppb increase in formaldehyde significantly exacerbated AD symptoms, particularly in spring (79.2%) and summer (39.9%).
- The effect was more pronounced in children aged 6-18 years and when indoor temperatures exceeded 25.5°C.
Conclusions:
- Indoor formaldehyde exposure can worsen AD symptoms in children, even at allowable levels.
- Spring and summer months showed a greater impact of formaldehyde on AD symptoms.
- Minimizing indoor formaldehyde exposure is recommended for effective AD management in children.
Purpose:
Evidence supporting a link between indoor formaldehyde exposure and atopic dermatitis (AD) in humans is limited. The purpose of this longitudinal study was to investigate whether AD symptoms in children could be affected by indoor formaldehyde levels in ordinary households.
Methods:
Fifty-five children with moderate-to-severe AD aged under 18 years were enrolled as a panel. They were followed up from February 2019 through February 2020. Indoor formaldehyde levels of patients' houses and their AD symptoms were repeatedly measured on a daily basis. The generalized linear mixed model was utilized for statistical analysis. Subdivision analysis was performed by stratifying patients by sex, body mass index, presence of parental allergy, and indoor environments including mold/dampness, temperature, and relative humidity (RH).
Results:
A total of 4,789 person-days of AD symptom data were collected. The average concentration of formaldehyde was 13.6 ± 16.4 ppb, with the highest value found in spring (18.1 ± 20.6 ppb). Higher levels of formaldehyde were observed when there was parental smoking, increased indoor temperature over 25.5°C, or RH over 60% (P < 0.0001). When the effect size was compared between each season after controlling for ambient particulate matter, temperature, and RH, an increase in 10 ppb of formaldehyde increased AD symptoms by 79.2% (95% confidence interval [CI], 19.6-168.4) in spring and by 39.9% (95% CI, 14.3-71.2) in summer. AD symptoms in children aged 6-18 years appeared to increase significantly, whereas there was no significant increase in children under 6 years. When indoor temperature was over 25.5°C, an increase in formaldehyde by 10 ppb increased AD symptoms by 17.8% (95% CI, 3.9-33.6).
Conclusions:
Indoor formaldehyde can exacerbate AD symptom in children with moderate-to-severe AD, particularly in spring and summer, even at allowable levels. Thus, minimizing exposure to indoor formaldehyde may be needed for the proper management of AD in children.
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