Interactive short-term effects of meteorological factors and air pollution on hospital admissions for cardiovascular diseases

Abstract

A substantial number of studies have demonstrated the association between air pollution and adverse health effects. However, few studies have explored the potential interactive effects between meteorological factors and air pollution. This study attempted to evaluate the interactive effects between meteorological factors (temperature and relative humidity) and air pollution ($\mathrm{SO}_{2}$, $\mathrm{NO}_{2}$, ${\mathrm{PM}}_{2.5}$, and ${\mathrm{O}}_{3}$) on cardiovascular diseases (CVDs). Next, the high-risk population susceptible to air pollution was identified. We collected daily counts of CVD hospitalizations, air pollution, and weather data in Nanning from January 1, 2014, to December 31, 2015. Generalized additive models (GAMs) with interaction terms were adopted to estimate the interactive effects of air pollution and meteorological factors on CVD after controlling for seasonality, day of the week, and public holidays. On low-temperature days, an increase of $10\mathrm{\mu g}/{\mathrm{m}}^{3}$ in $\mathrm{SO}_{2}$, $\mathrm{NO}_{2}$, and ${\mathrm{O}}_{3}$ was associated with increases of 4.31% (2.39%, 6.26%) at lag 2; 2.74% (1.65%, 3.84%) at lag 0–2; and 0.13% (0.02%, 0.23%) at lag 0–3 in CVD hospitalizations, respectively. During low relative humidity days, a $10\mathrm{\mu g}/{\mathrm{m}}^{3}$ increment of lag 0–3 exposure was associated with increases of 3.43% (4.61%, 2.67%) and 0.10% (0.04%, 0.15%) for $\mathrm{NO}_{2}$ and ${\mathrm{PM}}_{2.5}$, respectively. On high relative humidity days, an increase of $10\mathrm{\mu g}/{\mathrm{m}}^{3}$ in $\mathrm{SO}_{2}$ was associated with an increase of 5.86% (1.82%, 10.07%) at lag 0–2 in CVD hospitalizations. Moreover, elderly (≥ 65 years) and female patients were vulnerable to the effects of air pollution. There were interactive effects between air pollutants and meteorological factors on CVD hospitalizations. The risk that $\mathrm{SO}_{2}$, $\mathrm{NO}_{2}$, and ${\mathrm{O}}_{3}$ posed to CVD hospitalizations could be significantly enhanced by low temperatures. For $\mathrm{NO}_{2}$ and ${\mathrm{PM}}_{2.5}$, CVD hospitalization risk increased in low relative humidity. The effects of $\mathrm{SO}_{2}$ were enhanced at high relative humidity.