Fine Particles Show No Significant Short-Term Link to Cardiovascular Deaths in Almaty

Short-term exposure to fine particulate air pollution was not significantly associated with cardiovascular mortality in Almaty, Kazakhstan, according to a retrospective ecological time-series study published in Frontiers in Public Health. The research team, led by Gulnara Kulkayeva of the Salidat Kairbekova National Research Center for Health Development, analyzed daily cardiovascular deaths and environmental data spanning January 1, 2017 to December 31, 2025, a total of 3,287 days, in an effort to address a persistent evidence gap on air pollution and cardiovascular mortality in Central Asia. Over the study period, 43,095 cardiovascular deaths were recorded in the city.

The mean daily PM2.5 concentration was 36.9 micrograms per cubic meter, with a standard deviation of 33.3 micrograms per cubic meter, a figure that reflects both the level of fine particle pollution in Almaty and its considerable day-to-day variability. To estimate the association, the researchers used distributed lag nonlinear models embedded within a generalized additive model framework with a quasi-Poisson distribution. The team estimated both lag-specific associations for days zero through seven after exposure and cumulative associations across that window, while adjusting for long-term trends, day of the week, and nonlinear temperature effects.

The headline result was a null finding. Neither the lag-specific nor the cumulative associations between daily PM2.5 concentrations and cardiovascular mortality reached statistical significance. For the overall population, the cumulative relative risk was 1.011, with a 95 percent confidence interval running from 0.837 to 1.222, an interval that includes the null value of 1.0.

In practical terms, the data were consistent with anything from a modest reduction to a modest increase in cardiovascular deaths following high-pollution days, and could not distinguish between the two. Yet the study was not without structure in its findings. The relative risk estimates increased after exposure, peaked approximately two to four days later, and then declined.

Stratified analyses by age and sex pointed to a pattern worth noting. Adults aged 65 years and older exhibited the highest cumulative relative risk estimate of any subgroup, at 1.174, with a 95 percent confidence interval of 0.926 to 1.489. Here, as with the overall estimate, the confidence interval included the null value.

All subgroup confidence intervals in the study included the null, meaning that none of the subgroup findings can be considered statistically significant on their own. The authors conclude that short-term PM2.5 exposure was not significantly associated with cardiovascular mortality in Almaty, while emphasizing that the observed delayed pattern and the elevated point estimate among older adults suggested greater susceptibility in that age group. This is a careful framing: the study's point estimates are suggestive rather than confirmatory, and the authors present the age pattern as an observation consistent with heightened vulnerability rather than a demonstrated effect.

Several features of the study design are worth keeping in view when interpreting the results. As an ecological time-series analysis, the study links citywide daily mortality counts to citywide daily pollution measurements rather than to individual exposures, and its estimates depend on the statistical power available within a single city's data. The wide confidence intervals, particularly for the subgroup analyses, indicate substantial statistical uncertainty.

The study's regional significance lies in its setting. Central Asia has been underrepresented in the global body of air pollution epidemiology, and Almaty offers a case study for the region, with mean PM2.5 concentrations and day-to-day variability captured across more than eight years of daily observations. The finding that the city's average fine particle concentration stood at 36.9 micrograms per cubic meter underscores the public health relevance of the question, even as the mortality data did not yield a statistically significant short-term signal.

The observation that risk estimates rose in the two to four days after exposure and were highest in point estimate for adults aged 65 and older remains statistically unresolved, and the authors present it as such. Until further evidence accumulates, the association between short-term PM2.5 fluctuations and cardiovascular deaths in Almaty remains an open question that this dataset could not answer with confidence.

Subject of Research: Short-term associations between ambient PM2.5 exposure and cardiovascular mortality in Almaty, Kazakhstan

Article Title: Short-term effects of ambient PM₂.₅ exposure on cardiovascular mortality in Almaty, Kazakhstan

Article References: Kulkayeva, G., Kapanova, G., Mamyrkul, M., Kosherbayeva, L., & Yessergeneva, R. (2026). Short-term effects of ambient PM₂.₅ exposure on cardiovascular mortality in Almaty, Kazakhstan. Frontiers in Public Health, 14, Article 1950463. https://doi.org/10.3389/fpubh.2026.1950463

Image Credits: AI Generated

DOI: 10.3389/fpubh.2026.1950463

Keywords: PM2.5, air pollution, cardiovascular mortality, Almaty, Kazakhstan, distributed lag nonlinear model, time-series study, environmental health, older adults, Central Asia, Frontiers in Public Health, Short-term