Long-term ozone exposure tracked with lower kidney function in Thai workers
Long-term ozone exposure was associated with a measurable decline in kidney filtration among adult workers in Thailand’s Electricity Generating Authority cohort, adding another human data point to the growing concern that air pollution extends well beyond the lungs and heart. In this longitudinal analysis of the EGAT3 cohort, investigators linked higher estimated ozone exposure to lower estimated glomerular filtration rate, a functional marker clinicians use to gauge how well the kidneys are clearing waste from the blood.
The signal was modest in size, but it was consistent. After adjustment for potential confounders, an interquartile range increase in ozone concentration was associated with a -1.31% change in eGFR, with a 95% confidence interval from -1.68 to -0.93. The exposure difference tied to that estimate was 4.8 ppb, and the annual average ozone exposure across the follow-up period was 33.6 ppb.
Cohort design captured kidney function across a decade
The analysis drew on 2,022 adult workers from the EGAT3 cohort in the Bangkok metropolitan region, with baseline ages ranging from 25 to 55 years. Kidney function was measured in 2009, 2014, and 2019, giving the study repeated outcome assessments rather than a one-time snapshot. Exposure to ozone and other pollutants, including NO2, PM10, CO, and SO2, was estimated with the kriging method, and each participant’s average exposure was anchored to the year before follow-up.
That temporal structure matters because kidney decline rarely announces itself with a sharp clinical event. Small decrements in eGFR accumulate silently over years, often before albuminuria, hypertension progression, or overt chronic kidney disease becomes clinically obvious. A workplace-based cohort with repeated measurements is well suited to detecting those gradual shifts.
The association persisted when other pollutants entered the model
The investigators did not stop with a single-pollutant analysis. Two-pollutant models were performed to test whether the ozone association was merely standing in for coexisting urban pollutants. The relationship between ozone and eGFR did not change substantially when other pollutants were included, suggesting that the kidney signal was not easily explained away by the companion exposure estimates in this dataset.
For clinicians, that persistence is important because ambient air pollution rarely arrives as a lone exposure. Urban workers are typically breathing mixtures, not isolated compounds. When one pollutant continues to associate with renal decline even after adjustment for others, it strengthens the case for a biologically relevant effect rather than a statistical artifact driven by shared source patterns alone.
Why ozone could matter to the kidneys
The kidney is highly vascular, metabolically active, and sensitive to systemic injury. Ozone is a potent oxidant, and chronic exposure can plausibly promote oxidative stress, endothelial dysfunction, and inflammatory signaling, all of which can harm microvascular beds that sustain glomerular filtration. A sustained low-grade injury pattern could help explain why a pollutant best known for airway irritation shows up in kidney endpoints years later.
That mechanism is biologically credible even without direct tissue sampling in this cohort. Renal function often falls as vascular health erodes, and the glomerulus depends on intact capillary integrity and hemodynamic stability. If ozone exposure repeatedly stresses those pathways, the kidney may register the damage before symptoms appear.
Public health relevance extends beyond the occupational setting
These findings come from adult workers in the Bangkok metropolitan region, but the implication reaches well past one occupational cohort. Any population exposed to chronic urban ozone may carry similar renal risk, especially where heat, traffic emissions, and long commuting hours intensify cumulative inhalational burden. The study adds a kidney-focused dimension to environmental medicine, where air pollution is already implicated in cardiopulmonary and metabolic harm.
The result also fits the practical reality of nephrology prevention. eGFR is not just a lab value for patients with established kidney disease; it is a longitudinal marker that can reveal environmental injury long before dialysis-level disease ever enters the picture. A small percentage decline across a large exposed population can translate into a substantial number of people moving closer to clinically meaningful kidney impairment.
What the EGAT cohort can and cannot settle
This was an observational study, so it cannot prove that ozone caused the decline in kidney function. Residual confounding remains possible, even with multivariable adjustment and two-pollutant modeling. Exposure estimation by kriging is sophisticated, but it still represents modeled ambient exposure rather than personal real-time inhalation at the individual level.
Still, the study has several strengths: a sizeable cohort, repeated eGFR measurements over 10 years, and a defined working population with long-term follow-up. Ethical approval came from Ramathibodi Hospital, and the study was conducted with informed consent and no declared competing interests.
The central clinical message is straightforward. Long-term ozone exposure was linked to lower eGFR in this Thai adult worker cohort, and the association held up when other pollutants were considered. The next step is not speculation for its own sake, but better exposure characterization, replication in other populations, and closer attention to whether environmental ozone reduction can preserve kidney function over time.