Prenatal, Postnatal Exposure to Fine Particulate Matter Tied to Allergic Rhinitis

(Reuters Health) – Young children who have prenatal or postnatal exposure to fine particulate matter may have an increased risk for developing pediatric allergic rhinitis in early childhood, a recent study suggests.

Researchers examined data on 140,911 children in Taiwan, including 47,276 (33.6%) who were diagnosed with allergic rhinitis at a mean age of 2.97 years. Children had exposure to mean weekly concentrations of PM 2.5 of 34.26 micrograms/m3 during pregnancy and 33.56 mcg/m3 during the first year after birth.

An interquartile-range increase of 17.98 mcg/m3 during pregnancy (adjusted hazard ratio 1.27) and during the first year after birth (aHR 1.60) was significantly associated with incident allergic rhinitis.

The highest HR occurred 46 weeks after birth, the study team notes in Thorax. The exposure-response relationship revealed that the associations between AR and PM2.5 exposure were positive and significant with a PM2.5 between 26 and 76 mcg/m3 (aHRs ranged from 1.00 to 1.05 per 1 mcg/m3 increase).

“Our study found that the risk of allergic rhinitis development increased from 30 gestational weeks to 52 weeks after birth,” said senior study author Bing-Fang Hwang, dean of the college of public health at China Medical University in Taichung, Taiwan.

Researchers measured PM 2.5 using a combination of satellite time trend readings, land use data in Taichung, and meteorological variables. They matched infants’ home addresses at birth to estimated PM 2.5 levels in that location.

Several factors were associated with an increased risk of allergic rhinitis including male sex (HR 1.29), maternal atopy (HR 1.73), and maternal heart disease (HR 1.62).

One limitation of the study is that researchers were unable to account for any residential moves that might have impacted PM 2.5 exposure levels, the authors note. They were also unable to assess sensitization status in allergic rhinitis because they lacked data from lab tests for allergen-specific IgE-antibodies and skin tests.

In addition, many factors can modify the impact of air pollution on allergic rhinitis risk including stress, poverty, low education levels, and exposure to adversity or violence in neighborhoods, said Qihong Deng, a professor at the XiangYa School of Public Health at Central South University in Changsha, China, who wasn’t involved in the study.

“Mounting evidence indicated that children from families with lower socioeconomic status or stressful experiences are at higher risk of developing allergic diseases – especially asthma and allergic rhinitis – due to air pollution,” Deng said by email. “This implies that stress may operate through similar pathways to air pollutants, i.e. there is an interaction between them and thus we cannot separate their effects from each other.”

To reduce the risk of pediatric allergic rhinitis in communities with poor air quality, clinicians should advise pregnant women to reduce unnecessary outdoor activity and to use HEPA filter air purifiers or air conditioners with a PM 2.5 filter at home, Hwang said. Mothers should also consider wearing N95 or equivalent respirator masks when outdoors during periods of poor air quality.

Once babies are born, they should remain indoors as much as possible when concentrations of PM 2.5 are too high outside, Hwang added.

“If the children develop allergic rhinitis, we suggest the parents seek medical help promptly to prevent an altered facial growth and poor learning efficiency at school,” Hwang said.

SOURCE: Thorax, online March 11, 2021.

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