# The Association Between Humidex and Daily Outpatient Visits for Pediatric Respiratory Diseases in Shijiazhuang, China: A Time Series Analysis

## TL;DR

This study explores how temperature and humidity together affect children's respiratory health in Shijiazhuang, China, finding that low humidity poses a bigger risk than high humidity.

## Contribution

The study introduces humidex as a combined temperature-humidity metric to assess its impact on pediatric respiratory outpatient visits.

## Key findings

- Low humidex significantly increases the risk of respiratory diseases in children.
- Children aged 7–14 are more vulnerable to the effects of low humidex.
- The overall burden of non-optimal humidex on respiratory diseases is 13.96%.

## Abstract

At present, most studies have focused on the effects of temperature or humidity on children’s health, while relatively few have explored the combined effects of temperature and humidity on children’s health. We aimed to examine the impact of humidex, a comprehensive temperature and humidity index, on the outpatient department of respiratory diseases in children.

Daily outpatient visits for pediatric respiratory disorders, meteorological conditions, and air pollution in Shijiazhuang were recorded. From 2014 to 2022, we evaluated the impact of humidex on outpatient visits for respiratory disorders in children using a distributed lag non-linear model (DLNM). The model controlled air pollution (PM2.5, NO2, and SO2) and wind velocity, as well as day of week, seasonality, and long-term trend. In addition, stratified analysis was performed according to different genders, ages, and disease types.

Humidex and the outpatient exposure-response curve of children’s respiratory diseases showed a “V” type. The cumulative relative risks (CRR) of extremely high and low humidex were 1.124 (95% confidence interval [CI] = 1.030–1.228) and 1.344 (95% CI = 1.136–1.590), respectively. The burden of respiratory diseases in children attributed to non-optimal humidex was 13.96% (95% empirical CI[eCI] = 7.81–19.33%), most of which was attributed to low humidex, with an AF of 12.54% (95% eCI = 5.94–18.32%), and only 1.42% (95% eCI = 0.19–2.48%) was due to high humidex.

Low humidex exposure significantly increased the risk of respiratory illnesses in children, and children aged 7–14 were more susceptible to low humidex.