# Spatiotemporal Distribution of Hand, Foot, and Mouth Disease and the Influence of Air Pollutants and Socioeconomic Factors on Incidence in Fujian, China

## TL;DR

This study examines how hand, foot, and mouth disease spreads in Fujian, China, and how air pollution and population factors influence its occurrence.

## Contribution

The study identifies spatiotemporal patterns of HFMD and links specific air pollutants and demographic factors to its incidence.

## Key findings

- HFMD incidence in Fujian decreased after 2019, with annual peaks in May and June.
- Air pollutants like SO2, NO2, and CO showed increasing risk with higher concentrations, while O3 and PM2.5 showed decreasing risk at higher levels.
- Only the proportion of children under 15 was found to be associated with HFMD incidence among socioeconomic factors.

## Abstract

Background: Hand, foot, and mouth disease (HFMD) typically exhibits spatiotemporal clustering. This study aimed to analyze the spatiotemporal heterogeneity of HFMD in Fujian Province, China, and to identify the associations of air pollutants and socioeconomic factors with the incidence. Methods: Daily reported HFMD case data, daily air pollutant data, and socioeconomic data in Fujian Province from 2014 to 2023 were collected for analysis. A descriptive analysis was used to describe the epidemiological trends of HFMD. Spatial autocorrelation analysis was applied to explore the spatiotemporal clustering characteristics. The associations between risk factors and HFMD incidence were evaluated using the generalized additive model (GAM). Results: HFMD incidence in Fujian has decreased since 2019, and the peak in each year occurred between May and June. Distinct high–high and low–low clustering areas were identified. The cumulative exposure–response curves for SO2, NO2, and CO showed a monotonically increasing trend, with relative risks (RRs) < 1 at concentrations lower than the median levels (SO2 ≈ 4 μg/m3, NO2 ≈ 16 μg/m3, CO ≈ 1 mg/m3). In contrast, the curves for O3 and PM2.5 showed a decreasing trend, with RR < 1 at concentrations above the median levels (O3 ≈ 55 μg/m3, PM2.5 ≈ 20 μg/m3). Among socioeconomic factors, only the proportion of the population under 15 years old was found to be associated with HFMD incidence. Conclusions: HFMD incidence in Fujian exhibited distinct spatiotemporal clustering. The incidence was associated with the concentrations of air pollutants. Targeted interventions should be implemented in high-risk areas to mitigate HFMD transmission, with particular attention given to the environmental and demographic factors.