Night heart rate variability and particulate exposures among boilermaker construction workers

Area of Science:

• Occupational Health
• Cardiovascular Physiology
• Environmental Health

Background:

• Existing research links ambient particulate matter to heart rate variability (HRV).
• The specific impact of metal-rich, occupational particulate exposures on HRV, especially nocturnal HRV, remains under-investigated.
• Understanding these associations is crucial for assessing occupational cardiovascular risks.

Purpose of the Study:

• To investigate the relationship between long-duration HRV, including nighttime HRV, and occupational fine particulate matter (PM2.5) exposures.
• To quantify the impact of workday PM2.5 exposure on various HRV metrics.

Main Methods:

• Utilized 24-hour ambulatory electrocardiograms (ECGs) in 36 male boilermaker welders.
• Measured HRV in time-domain (rMSSD, SDNN, SDNN(i)) over 24-hour, daytime, and nighttime periods.
• Assessed PM2.5 exposure via workday monitoring and calculated 8-hour time-weighted averages, using non-workday data for risk factor control.

Main Results:

• A consistent inverse exposure-response relationship was observed between PM2.5 and HRV.
• Increased PM2.5 exposure was associated with decreased HRV measures across all periods.
• The most pronounced decreases in HRV occurred during nighttime, with a 1 mg/m³ increase in PM2.5 linked to significant reductions in nighttime rMSSD, SDNN, and SDNN(i).

Conclusions:

• Occupational exposure to metal-rich particulate matter is associated with reduced long-duration HRV, particularly during sleep.
• These findings suggest a potential cardiovascular risk for workers exposed to such environments.
• Further research is warranted to identify specific metal constituents responsible for HRV reduction.