Meteorological factors tied to occurrence of AD symptoms
Meteorological factors, such as air pollutants, temperature and relative humidity (RH), are associated with atopic dermatitis (AD) symptoms in young children, a new study shows.
The study involved 177 paediatric patients (110 males) with AD who were at most 5 years of age (average 2.0 years). Follow-up period lasted 17 months. Using a smartphone-adjusted diary developed by researchers, parents recorded AD symptoms (oedema, oozing, dryness, erythema, sleep disturbance and itching) and rated them on a scale of 0 to 4.
The database of the Korean Meteorological Association was accessed for data on meteorological factors, including hourly outdoor RH, daily rainfall and hourly outdoor temperature. Ambient air pollution information were retrieved from the National Institute of Environmental Research.
Over the course of the 17-month follow-up, 49.9 and 39.4 percent of boys and girls, respectively, showed symptoms of AD (p<0.0001).
Daily mean RH and temperature were 64.9 percent and 15.0oC, respectively. Mean PM10, NO3 and O3 concentrations were 45.2 µg/m3, 32.4 ppb and 38.1 ppb, respectively. Average rainfall and diurnal temperature range (DTR) values were 2.7 mm/day and 8.9oC, respectively.
An increase of 5oC in outdoor temperature was positively associated with a 12.8-percent (95 percent CI, 10.5 to 15.2 percent) decrease in AD symptoms on the same day. Similarly, an increase of 5 percent in outdoor RH was associated with a 3.3-percent (1.7 to 4.7 percent) decrease in AD symptoms on the same day.
On the other hand, AD symptoms increased by 7.3 percent (3.6 to 11.1 percent) when the amount of rainfall increased by 5 mm on the days that had <40 mm of rainfall. On days that were >14oC DTR, a 5oC increase in DTR was associated with a 284.9-percent (67.6 to 784.2 percent) increase in the risk of AD symptoms.
Finally, the risk of AD symptoms increased by 3.2 percent (1.5 to 4.9 percent), 5.0 percent (1.4 to 8.8 percent) and 6.1 percent (3.2 to 9.0 percent) according to a 10-unit increase in the concentrations of PM10, NO2 and O3, respectively.