Differences in heart rate variability associated with long-term exposure to NO2

Area of Science:

• Environmental Health
• Cardiology
• Epidemiology

Background:

• Heart rate variability (HRV) reflects cardiac autonomic tone and is linked to cardiovascular outcomes.
• Previous short-term studies suggest traffic-related air pollution negatively impacts HRV.

Purpose of the Study:

• To examine the long-term effects of nitrogen dioxide (NO2) exposure on HRV within the Swiss SAPALDIA cohort.
• Investigate the association between chronic NO2 levels and cardiac autonomic function in adults aged 50 and older.

Main Methods:

• Collected 24-hour ECGs from 1,408 randomly selected SAPALDIA participants aged 50+.
• Estimated annual NO2 exposure using hybrid models combining dispersion, land-use, and meteorological data.
• Analyzed the association between NO2 and HRV parameters using multivariable linear regression.

Main Results:

• A 10 μg/m³ increase in annual NO2 was associated with reduced HRV measures in women: SDNN (-3%), nighttime LF (-6%), and nighttime LF/HF ratio (-5%).
• No significant effects were observed for most HRV parameters in men.
• Individuals with self-reported cardiovascular issues showed a 4% decrease in SDNN per 10 μg/m³ NO2 increment.

Conclusions:

• Long-term exposure to NO2 shows a potential association with cardiac autonomic dysfunction.
• Elderly women and individuals with pre-existing cardiovascular disease may be particularly susceptible to NO2's adverse effects on HRV.