Associations between short-term PM 2.5 exposure and major cardiovascular events in high-risk population: a nationwide case-crossover study

Q: What are the key findings of this study?

Short-term PM2.5 exposure per 10 µg/m³ increase was associated with increased odds of 4P-MACE (OR 1.06, 95% CI 1.01-1.11 for single-day lags 1 to 4) in high-risk cardiovascular patients.

Q: What is the clinical evidence from this study?

Study design: Case-Control. Population: High atherosclerotic cardiovascular disease risk with four-point major adverse cardiovascular events (n=1121). Intervention: Short-term ambient PM2.5 exposure (per 10 µg/m³ increase over lag 0 to 7 days) vs. Self-matched control periods separated by a 4-week window. Primary outcome: First-time four-point major adverse cardiovascular event (4P-MACE: non-fatal myocardial infarction, non-fatal stroke, heart failure hospitalisation, and all-cause death) (OR 1.06, 95% CI 1.01-1.11, p=<0.05).

Q: What does this research mean for the field?

Short-term PM2.5 exposure significantly increases the risk of major adverse cardiovascular events in individuals with high baseline atherosclerotic cardiovascular risk. Novelty: ClaimNovelty.CONFIRMATORY. Consensus alignment: ConsensusAlignment.SUPPORTS_CONSENSUS.

Q: What question did this study set out to answer?

To assess the association between short-term exposure to fine particulate matter (PM2.5) and acute major adverse cardiovascular events among individuals with significant atherosclerotic risk.

Wanwarang Wongcharoen; Benjapa Phanthasuporn; Wachiranun Sirikul; Siriluck Gunaparn; Nichanan Osataphan; Sasivimon Jai-aue; Rungroj Krittayaphong; Arintaya Phrommintikul

doi:10.1136/bmjopen-2026-120476

October 1, 2026BMJ OpenOpen Access

Associations between short-term PM 2.5 exposure and major cardiovascular events in high-risk population: a nationwide case-crossover study

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Key result

Short-term PM2.5 exposure is linked to ~6% higher 4P-MACE odds per 10 µg/m³.

OR 1.06
95% CI 1.01-1.11
P<0.05
n=1,121

Figures

Why the study?

While short-term PM2.5 exposure is a recognised risk factor for acute cardiovascular events in the general population, data regarding its effects in high-risk populations with significant atherosclerotic risk are limited.

Does short-term ambient PM2.5 exposure increase the risk of four-point major adverse cardiovascular events (non-fatal MI, non-fatal stroke, HF hospitalisation, and all-cause death) in a high-risk atherosclerotic population in Thailand?

Key Points

To assess the association between short-term exposure to fine particulate matter (PM2.5) and acute major adverse cardiovascular events among individuals with significant atherosclerotic risk.
Conducted a time-stratified case-crossover study using data from 1,121 patients in the nationwide CORE-Thailand registry who experienced a four-point major adverse cardiovascular event (4P-MACE) between 2011 and 2019.
Matched daily PM2.5 concentrations from nearby ambient monitoring stations during event periods and corresponding control periods.
Applied conditional logistic regression models to compute odds ratios for 4P-MACE per 10 µg/m³ increase in PM2.5 across lag periods spanning 0 to 7 days.
A 10 µg/m³ increase in PM2.5 was significantly associated with elevated odds of 4P-MACE on single-day lagged exposures from lag 1 to lag 4 (OR 1.06, 95% CI 1.01–1.11).
Cumulative multi-day exposures over lag periods 0–1 to 0–4 days demonstrated statistically significant associations with 4P-MACE, with ORs ranging between 1.06 and 1.08.

Study Design

Type

Case-Control (n=1,121)

Multicenter

Yes

Structured PICO

Does short-term ambient PM2.5 exposure increase the risk of four-point major adverse cardiovascular events (non-fatal MI, non-fatal stroke, HF hospitalisation, and all-cause death) in a high-risk atherosclerotic population in Thailand?

P

Population

1,121 high-risk adults (mean age 69.9 years, 44.2% female) from 25 centers in Thailand with ≥3 atherosclerotic risk factors or documented CVD who experienced a first-time 4P-MACE over a median follow-up of 58.2 months.

E

Exposure

Short-term ambient PM2.5 exposure (particulate matter with a diameter ≤2.5 µm), assessed as daily mean concentrations (24-hour averages, per 10 µg/m³ increase) during the 7-day window immediately preceding the major CV event (single-day lags 0 to 7 and average-day lags 01 to 07).

C

Comparator

Self-matched control periods using a time-stratified case-crossover design, where each participant served as their own control during a 7-day window in the corresponding time of year separated by a 4-week gap/buffer from the event period.

O

Outcome

First occurrence of four-point major adverse cardiovascular events (4P-MACE), a composite of non-fatal acute myocardial infarction, non-fatal stroke, heart failure hospitalisation, and all-cause death, assessed over a median follow-up of 58.2 months (5 years total longitudinal follow-up) and evaluated across lag periods of 0 to 7 days.composite

Main Result

Odds Ratio: 1.06 (95% CI 1.01–1.11)

p-value: p=<0.05

Short-term ambient PM2.5 exposure is significantly associated with a 6% to 8% increased odds of acute major adverse cardiovascular events per 10 µg/m³ increment in patients with high baseline atherosclerotic risk, underscoring the need to integrate air pollution mitigation into secondary cardiovascular prevention.

Limitations

Exposure misclassification from relying on monitoring stations nearest to index hospitals rather than residential or occupational addresses
Residual confounding by seasonality and unmeasured time-varying meteorological variations across the 4-week control buffer
Exclusion of 17.7% of eligible MACE cases due to insufficient localized PM2.5 monitoring data
Lack of data on short-term time-varying confounders such as psychological stress, physical activity, and acute blood pressure changes
Limited statistical power for exploratory analyses of individual MACE components like non-fatal stroke and heart failure hospitalization
PM2.5 exposure was estimated from monitoring stations nearest to index hospitals rather than participants' residential or occupational locations, which may cause spatial exposure misclassification and does not account for indoor air pollution or mobility.
Residual confounding by seasonality and meteorological variation (e.g., temperature, rainfall) cannot be excluded, as detailed time-varying meteorological variables were not systematically incorporated.
Potential selection bias due to the exclusion of 17.7% (243/1,364) of eligible MACE cases because of insufficient localized PM2.5 exposure data.
Short-term, time-varying factors such as psychological stress, physical activity, and blood pressure changes were not systematically collected.
Limited statistical power for exploratory analyses of individual 4P-MACE components (especially non-fatal stroke and heart failure hospitalisation) and potential limited generalisability as data were collected from 2011 to 2019 mostly from Northern and Central Thailand.

Implication

Short-term PM2.5 exposure was associated with higher 4P-MACE odds in high-risk patients; extends prior evidence but remains hypothesis-generating for targeted prevention.

Abstract

OBJECTIVES: While particulate matter with a diameter ≤2.5 µm (PM(2.5)) is a recognised major modifiable risk factor with well-documented short-term impacts on acute cardiovascular events in the general population, data regarding its effects on high-risk populations with significant atherosclerotic risk are limited. This study aims to identify the association between short-term exposure to PM(2.5) and acute major cardiovascular events in Thailand. DESIGN: A time-stratified case-crossover design. SETTING: The nationwide Cohort Of patients with high Risk for cardiovascular Events-Thailand registry (CORE-Thailand registry). PARTICIPANTS: A total of 1121 individuals from the registry who experienced four-point major adverse cardiovascular events (4P-MACEs) between 2011 and 2019. PRIMARY OUTCOME MEASURE: The primary exposure was defined as short-term PM(2.5) exposure, with the primary outcome being a first-time MACE, which included acute myocardial infarction, stroke, heart failure hospitalisation and all-cause death. METHODS: Using a time-stratified case-crossover design, the analysed events included non-fatal myocardial infarction, non-fatal stroke, heart failure hospitalisation and all-cause death. Daily PM(2.5) concentrations during the event and control periods were obtained from nearby air quality monitors. Conditional logistic regression models assessed odds ratio (ORs) for 4P-MACE per 10 µg/m³ increase in PM(2.5) exposure over lag periods from 0 to 7 days. RESULTS: The participants had a mean age of 69.9 years and 55.8% were male. Most had pre-existing atherosclerotic cardiovascular diseases (74.6%), diabetes mellitus (58.4%), hypertension (98.1%) and dyslipidaemia (83.3%). Significant associations were observed for both single-day (lag 1 to lag 4) and average-days (lag 01 to 07) PM(2.5) exposures. A 10 µg/m³ increase in PM(2.5) was associated with increased odds of MACEs, with ORs of 1.06 (95% CI 1.01 - 1.11) for single-day lagged exposures and varying ORs from 1.06 to 1.08 for average-days lagged exposures (lags 01 to 04). CONCLUSIONS: Short-term PM(2.5) exposure significantly increased the risk of MACE in the Thai population with high atherosclerotic risk. These findings underscore the urgency of public health interventions aimed at mitigating air pollution exposure, especially among vulnerable groups. TRIAL REGISTRATION: The study is registered with the Thai Clinical Trials Registry (TCTR20130520001).

Discussion

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Cite This Study

Wongcharoen et al. (2026) conducted a case-control in High atherosclerotic cardiovascular disease risk with four-point major adverse cardiovascular events (n=1,121). Short-term ambient PM2.5 exposure (per 10 µg/m³ increase over lag 0 to 7 days) vs. Self-matched control periods separated by a 4-week window was evaluated on First-time four-point major adverse cardiovascular event (4P-MACE: non-fatal myocardial infarction, non-fatal stroke, heart failure hospitalisation, and all-cause death) (OR 1.06, 95% CI 1.01-1.11, p=<0.05). Short-term PM2.5 exposure per 10 µg/m³ increase was associated with increased odds of 4P-MACE (OR 1.06, 95% CI 1.01-1.11 for single-day lags 1 to 4) in high-risk cardiovascular patients.

synapsesocial.com/papers/6add4812322f548a006b13c9 https://doi.org/10.1136/bmjopen-2026-120476

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Associations between short-term PM 2.5 exposure and major cardiovascular events in high-risk population: a nationwide case-crossover study

Figures

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

Associations between short-term PM 2.5 exposure and major cardiovascular events in high-risk population: a nationwide case-crossover study

Figures

Key Points

Study Design

Structured PICO

Main Result

Limitations

Implication

Abstract

Discussion

Cite This Study

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