Short-Term Association Between Air Pollutants and Outpatient Visits for Conjunctivitis in an Arid Industrial City of Northwest China: A Time-Series Study
Jul 2026· Aerosol and Air Quality Research· 0 citations
Abstract
This study aims to quantify the short-term association between ambient air pollutants and outpatient visits for conjunctivitis using empirical data. Methods: This study collected daily outpatient visits for conjunctivitis in Jiayuguan City from January 1, 2023 to December 31, 2024, as well as meteorological and air pollutant data during the same period. We used a quasi-Poisson generalized linear regression model that incorporates a distributed lag nonlinear model to analyze the nonlinear relationship and lag effect between pollutant exposure and the risk of outpatient visits for conjunctivitis, and conducted stratified analysis by gender, age and season to identify susceptible populations. Results: A total of 14,598 cases of conjunctivitis were included during the study. The results showed that particulate matter (PM
2.5
and PM
10
) was not statistically significantly associated with outpatients for conjunctivitis, and the exposure-response curve showed a downward trend. Conversely, gaseous pollutants (NO
2
and CO) showed a significant positive linear correlation with outpatients for conjunctivitis, with the effect being stronger in the cold season. NO
2
was significant at lag1-3, lag5 days and lag02–07 days, with each 10 µg/m
3
increase corresponding to an RR of 1.126 (95% CI 1.050, 1.208), corresponding to a 12.60% increase in patient visits. CO had the strongest effect at lag07 days (RR = 1.836, 95% CI 1.126, 2.991). Furthermore, NO
2
primarily increases conjunctivitis visits in women and children (0–14 years), while CO exposure is significantly associated with conjunctivitis visits in men and older adults (≥ 65 years). Conclusions: In this arid, industrial city in Northwest China, gaseous pollutants (rather than particulate matter) are the key environmental factor driving the increase in conjunctivitis outpatient visits. This study reveals the differentiated effects of specific pollutants on populations with different demographic characteristics, highlighting the public health significance of strengthening ocular surface health protection for specific vulnerable subgroups during the cold season.
Objective Herpangina (HA) is a common acute infectious disease in children that may exhibit epidemiological patterns associated with meteorological factors. This study investigated the short-term and lagged associations of temperature and relative humidity with daily outpatient visits for HA in Guangzhou and explored patterns across sex and age groups. Methods Daily outpatient visits for HA, daily mean temperature, relative humidity, and particulate matter with an aerodynamic diameter of 2.5 micrometers or less (PM2.5) were collected from January 1, 2014 to December 31, 2023. A quasi-Poisson generalized linear model combined with distributed lag nonlinear models was used to estimate exposure-lag-response associations. Temperature, relative humidity, and PM2.5 cross-basis terms were included simultaneously, with adjustment for long-term trends, seasonality, day of week, public holidays, and the COVID-19 period. Results During the study period, 83,146 HA outpatient visits were recorded, 56.4% of which were among male patients. Daily outpatient visits showed clear seasonal variation, with larger peaks generally occurring during summer and autumn. Compared with the median temperature (24.38 °C), the cumulative RR was 0.482 (95% CI: 0.353–0.657) at the 2.5th percentile (10.77 °C) and 1.966 (95% CI: 1.714–2.254) at the 97.5th percentile (30.63 °C) over lags 0–14 days. Compared with the median relative humidity (79.15%), the cumulative RR was 0.878 (95% CI: 0.795–0.970) at the 10th percentile (62.21%) and 1.477 (95% CI: 1.297–1.682) at the 97.5th percentile (93.21%) over lags 0–20 days. High-temperature and high-humidity associations were observed across sex and age strata. The lower-humidity association was less robust in sensitivity analyses. Conclusion High temperature and high relative humidity were associated with increased daily outpatient visits for HA in Guangzhou, whereas low temperature and lower relative humidity were associated with fewer visits in the main model. The lower-humidity estimate was less stable across alternative temporal-control settings. These findings support incorporating lagged meteorological information into HA surveillance and preparedness.
Feifei Yan, Rong Xu, Yi Dong et al.· Frontiers in Pediatrics· 0 citations
Background Meteorological conditions are increasingly recognized as important determinants of allergic diseases; however, their temporal dynamics and delayed effects on allergic rhinitis (AR) remain inadequately characterized, particularly in subtropical settings. This study aimed to examine the non-linear and lagged relationships between major meteorological variables and AR-related outpatient visits in Wuxi, a representative subtropical city in eastern China. Methods A time-series analysis was conducted using data from 76,760 AR outpatient visits recorded in Wuxi, China, between November 2020 and December 2024. Daily meteorological variables, including mean temperature, atmospheric pressure, relative humidity, wind speed, and air pollution indicators were obtained from local monitoring stations. Distributed lag non-linear models (DLNM), coupled with quasi-Poisson regression, were employed to estimate exposure–response relationships and lagged effects, with adjustment for long-term trends, seasonality, and day-of-week effects. Results AR outpatient visits showed clear seasonal variation, with a major autumn peak and a secondary spring peak, and were predominantly concentrated among children and younger adults. Daily mean temperature was positively and non-linearly associated with AR outpatient visits, with risk increasing progressively above approximately 15 °C. Compared with 15 °C, the cumulative relative risk reached 1.19 at 25 °C and 1.41 at 30 °C, and the association was mainly acute, peaking within lag 0–3 days. In the primary single-exposure DLNM, lower atmospheric pressure showed an inverse exposure–response pattern and a delayed lag structure, with the strongest association observed around lag 8–10 days. However, pressure-related estimates were less stable in co-meteorological-adjusted and age-stratified analyses, suggesting that low atmospheric pressure may reflect broader synoptic weather conditions rather than an isolated independent exposure. Relative humidity and wind speed showed no robust independent associations. Conclusion In this humid subtropical population, higher temperature was consistently associated with rapid increases in AR outpatient visits. Lower atmospheric pressure showed a delayed association in the primary model, but this pattern was less robust after accounting for correlated meteorological variables and across age strata. These findings provide epidemiological evidence for climate-sensitive AR prevention and support the incorporation of meteorological indicators into seasonal surveillance, early warning systems, and healthcare resource planning.
Jian Peng, Ganglei Shen, Kehong Zhang et al.· Frontiers in Public Health· 0 citations
Findings provide the first long-term evidence from Guangzhou that short-term NO2 and SO2 exposure is positively associated with childhood bronchopneumonia hospitalization, with older children and boys being the susceptible subgroups.
Qi Yue, Qian Nie, Weiling Liu et al.· Frontiers in Public Health· 0 citations
Background: This study aims to thoroughly examine the relationship between weather conditions and reported pulmonary tuberculosis (PTB) cases in Haikou City. The goal is to provide a scientific basis for developing more targeted and timely prevention measures, thereby enhancing local efforts to control PTB. Methods: In this retrospective time-series study from 2010 to 2023, a total of 22,083 PTB cases (15,723 males and 6360 females) were analyzed. Using monthly PTB case counts (overall and stratified by sex and age) and meteorological variables, descriptive analyses along with distributed lag non-linear models (DLNMs) and generalized additive distributed lag models (GADLMs) combined with quasi-Poisson regression model regression were applied. Results: Taking the median of each meteorological factor as the reference, temperature exhibited significant delayed effects. For the overall population, temperatures between 14.30 °C and 24.24 °C posed significant lagged risks, with the effect decreasing as temperature rose. At the minimum monthly average temperature (14.30 °C), the relative risk (RR) peaked at lag 7 months (RR = 1.37, 95% CI: 1.23–1.53). Sex-stratified analysis showed similar patterns for males (14.30–23.94 °C) and females (14.30–23.84 °C), with peak RRs of 1.40 (1.25–1.58) and 1.37 (1.21–1.56), respectively, at 14.30 °C. In the adults group, temperatures between 14.30 °C and 25.45 °C produced significant lagged effects (maximum lag 14 months), with the highest RR of 1.42 (1.27–1.60) at lag 8 under 14.30 °C. The older age group showed a linear association. Average relative humidity exhibited a weak lag-4 correlation with PTB counts in some subgroups, but model testing indicated no statistically significant lagged risk effect in any group. Conclusions: A significant nonlinear lagged exposure–response relationship exists between temperature and PTB incidence in Haikou, with population-specific variations, while relative humidity shows no significant lagged effect. These findings underscore the necessity of incorporating temporal lag effects and population differences into regional PTB early warning and prevention strategies.
Short-term absolute changes in ambient air pollution levels may result in disease events such as depression, whereas evidence from large-scale epidemiological studies has been insufficient. A time-stratified case-crossover study was performed to investigate the associations between air pollution increases between neighboring days (APINs, generated as the differences in absolute air pollution concentrations on the current days minus those on the previous days) and morbidity risks of depression based on hospital admission and outpatient visit data from 239 Chinese cities of prefecture-level or above during 2013-2017. Daily absolute concentrations of particulate matter with an aerodynamic diameter ≤ 2.5 μm (PM2.5), particulate matter with an aerodynamic diameter ≤ 10 μm (PM10), nitrogen dioxide (NO2), sulfur dioxide (SO2), carbon monoxide (CO) and ozone (8 h O3) were obtained, and conditional logistic regression models were used to evaluate the associations between absolute concentrations and APINs of major air pollutants with morbidity risks of depression. A total of 330,610 hospital admissions and 3,726,390 outpatient visits for depression were included. Per interquartile range (IQR) increase in APINs of major air pollutants at lag 0-3 were associated with increases ranging from 0.59% (0.06%, 1.13%) (8 h O3) to 1.66% (1.09%, 2.22%) (NO2) in hospital admissions for depression; and with increases ranging from 0.42% (0.15%, 0.68%) (8 h O3) to 0.85% (0.56%, 1.14%) (NO2) in outpatient visits for depression, which were robust to adjustments for absolute concentrations of major air pollutants (with the exception of 8 h O3). This study provides novel evidence that short-term absolute increases in air pollution levels are associated with elevated risks of depression, which is worth consideration in future disease prevention practices.
Yating Ma, Chenlu Yang, Lijun Bai et al.· Ecotoxicology and Environmen...· 0 citations
Short-term exposure to PM2.5, PM10, SO2, NO2, and CO was associated with increased AECOPD hospitalization risk, with nonlinear, lagged, and cumulative effects, and older adults and females may be more susceptible to ambient air pollution.
Huixia Shi, Jiajun Li, Bo-Yan Li et al.· Medicine· 0 citations
