Low Level Of Ambient Carbon Monoxide Exposure and Blood Pressure: A Longitudinal Panel Study at the Hourly Level (December 2025)-Low Level Of Ambient Carbon Monoxide Exposure and Blood Pressure: A Longitudinal Panel Study at the Hourly Level

Low Level Of Ambient Carbon Monoxide Exposure and Blood Pressure: A Longitudinal Panel Study at the Hourly Level

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This longitudinal panel study investigated the acute effects of low-level ambient carbon monoxide (CO) exposure on blood pressure (BP) among 40 healthy Chinese college students in Hefei, China, from August to October 2021. Participants underwent four health examinations at two-week intervals, measuring systolic blood pressure (SBP), diastolic blood pressure (DBP), and mean arterial pressure (MAP). Ambient CO and other air pollutants were monitored hourly using nearby fixed stations. Linear mixed-effect models examined the associations between CO exposure at various lag times (from hours to days) and BP, adjusting for covariates including age, sex, body mass index (BMI), temperature, and humidity.<br /><br />Results showed that increases in CO levels—even well below World Health Organization safety thresholds—were significantly associated with elevated SBP, DBP, and MAP. The strongest associations were found for CO exposure averaged over lags of 0–72 hours and at single lag intervals of 25–48 hours. For example, a 0.14 mg/m³ interquartile range (IQR) increase in CO over 0–72 hours was linked to increases of 2.91 mm Hg in SBP, 4.35 mm Hg in DBP, and 3.88 mm Hg in MAP. Notably, females and individuals with abnormal BMI (underweight or overweight/obese) exhibited greater BP increases in response to CO exposure.<br /><br />Sensitivity analyses adjusting for other air pollutants (PM2.5, NO2, O3, and SO2) confirmed the robustness of associations, though effects slightly attenuated when controlling for NO2 and PM2.5. The findings support the notion that even low-level ambient CO exposure can acutely elevate BP—a well-known cardiovascular risk factor—possibly via pathways involving inflammation, oxidative stress, and endothelial dysfunction.<br /><br />Limitations include the small sample size, restriction to young college students limiting generalizability, and reliance on fixed monitoring station data instead of personal exposure measures. Despite these, the study highlights that short-term CO exposure at concentrations below regulatory thresholds can induce subclinical adverse cardiovascular effects, with potential implications for hypertension and cardiovascular disease development, particularly in susceptible groups defined by sex and BMI. The research underscores the need for ongoing investigation into ambient CO’s cardiovascular impact and consideration of vulnerable populations in environmental health policies.

Keywords

ambient carbon monoxide

blood pressure

systolic blood pressure

diastolic blood pressure

mean arterial pressure

low-level CO exposure

cardiovascular risk

Chinese college students

linear mixed-effect models

air pollution