Nighttime Airplane Noise Linked to Cardiovascular Death

Batya Swift Yasgur, MA, LSW

December 08, 2020

People exposed to nighttime airplane noise may be at increased risk for death from cardiovascular disease within as little at 2 hours of noise exposure, new research suggests.

A team of Swiss investigators analyzed almost 25,000 deaths from cardiovascular causes among individuals living close to Zurich Airport (ZRH) and found that aircraft noise contributed to roughly 3% of all cardiovascular deaths.

In particular, the risk for cardiovascular death increased by 33% when nighttime noise levels were between 40 and 50 dB and by 44% with noise levels above 55 dB.

"The take-home messages of these findings are that adaptations and mitigations of nighttime noise are warranted," senior author Martin Röösli, PhD, professor of environmental epidemiology, Swiss Tropical and Public Health Institute, University of Basel, Basel, Switzerland, and head of the Environmental Exposures and Health Unit, Swiss Tropical and Public Health Institute, Associate Institute of the University of Basel, told | Medscape Cardiology.

"Clinicians may consider noise exposure as an additional risk factor in evaluating [a patient's] case history," he said.

The study was published online November 20 in the European Heart Journal.

Case-Crossover Design

Environmental noise exposure contributes to an estimated 48,000 new cases of ischemic heart disease annually. Previous research has focused primarily on long-term effects; shorter-term risk has not been sufficiently investigated, Röösli said.

In particular, he added, it's necessary to better understand whether noise exposure also acts as a trigger for cardiovascular events and how the timing of noise exposure modulates that response.

To investigate the question, the researchers analyzed 15-year data from the Swiss National Cohort (SNC), which links national census and mortality records for the entire Swiss population. The SNC contains personal information as well as household, building, and mortality data (including hour and cause of death).

The researchers focused on 24,886 individuals who were older than 30 years, had died from cardiovascular causes, and had lived near the Zurich airport.

The researchers linked all aircraft movements at ZRH between 2000 and 2015 to preexisting outdoor aircraft noise exposure calculations. Using a case-crossover design, they matched each case of death with up to 4 control days selected within the same month and day of the week. They then separately examined deaths that occurred during the day (defined as 07:00 to 23:00) and deaths that occurred at night (defined as 23:00 – 07:00).

"This study design is very useful to study acute effects of noise exposure with high day-to-day variability, such as for airplane noise, given changing weather conditions or flight delays," lead author Apolline Saucy, a PhD candidate at the Tropical and Public Health Institute, explained in a press release.

"With this temporal analysis approach, we can isolate the effect of unusually high or low levels of noise on mortality from other factors. Lifestyle characteristics, such as smoking or diet, cannot be a bias in this study design," Saucy said.

The researchers assessed associations during a 2-hour exposure window that preceded nighttime deaths. For daytime deaths, they assessed associations at five exposure windows within the night preceding the day of the event:

  • Overall night (12:00 – 7:00)

  • Late evening (19:00 – 23:00)

  • Reduced air traffic reserved for delayed flights (23:00 – 23:30)

  • Core night (23:30 – 6:00)

  • Early morning (6:00 – 7:00)

All noise metrics were highest during the evening time window and lowest during core night.

They also took into account long-term nighttime exposure to railway and road traffic noise at home locations for the year of death, as well as air pollution and meteorologic factors.

Amplified Stress Response

Of the 24,886 cardiovascular deaths, 7641 occurred during the night, and 17,245 occurred during the day.

Roughly 3% of the total number of deaths (n = 782) were attributable to aircraft noise (ie, exposure within the 2 hours preceding death) — an estimate "comparable to other triggers of cardiovascular mortality, such as anger, positive emotions, sexual activity, and heavy meals, and to previous estimates for long-term aircraft noise exposure," the authors comment.

Nighttime noise exposure during the 2-hour window was significantly associated with all-cause cardiovascular mortality for those with noise exposure from 40 to 50 dB as well as those exposed to noise above 50 dB (odds ratio [OR], 1.33; 95% CI, 1.05 – 1.67; and OR, 1.44; 95% CI, 1.03 – 2.04, respectively; P for trend = .01).

These associations were found among patients with heart failure (P for trend = .05) and were "suggestive" among patients with ischemic heart disease but did not reaching clinical significance (P for trend = .18).

The odds of mortality within the 2-hour exposure time frame were higher for women than men (OR, 1.13; 95% CI, 1.04 – 1.23; vs OR, .98; 95% CI, 0.89 – 1.07), particularly for arrhythmias.

Swiss men had a lower risk for mortality compared to other European men. Those with lower educational level, lower socioeconomic status, and older age had a higher level of risk.

Notably, divorced people had the highest odds of mortality (OR, 1.22; 95% CI, 1.00 – 151). Married men had the lowest risk for mortality (OR, 0.98; 95% CI, 0.87 – 1.11) compared to married women, whose risk was as high as that of divorced women (OR, 1.22; 95% CI,1.01 – 1.48).

Röösli explained that noise causes a stress response via activation of the autonomic nervous system and the hormonal system.

"In addition, this stress response is amplified by sleep problems, which may also be the consequences of noise exposure," he suggested.

"Strong, Innovative" Study

Commenting on the study for | Medscape Cardiology, Mathias Basner, MD, PhD, MScEpi, professor and director, Behavioral Regulation and Health Section, Unit for Experimental Psychiatry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, called it "a strong, innovative study."

The use of a large national cohort made the study particularly "powerful" and "brought both calculations of the exposure side and the link to health data."

Aircraft noise differs from the steadier noise of a busy highway. "A single intermittent noise, such as that of an airplane, can trigger an autonomic nervous system response and be considered a trigger event for having a fatal event such as a heart attack," suggested Basner, who was not involved with the study.

Also commenting on the study for | Medscape Cardiology, Thomas Münzel, MD, chief of the Department of Cardiology, Johannes Gutenberg University Mainz, Mainz, Germany, said, "There is now substantial evidence that [aircraft] noise is a cardiovascular risk factor that cannot be modified by patients or doctors."

Münzel, who was not involved with the study, suggested that modification can be made by politicians and the cardiovascular societies by "reinforcing, for example, the new noise limits published in the WHO guidelines concerning road, aircraft, and railway noise."

The study was supported by a grant from the Boehringer Ingelheim Foundation and by the Foundation Heart of Mainz and the DZHK (German Center for Cardiovascular Research), Partner Site Rhine–Main, Mainz, Germany. Röösli and coauthors, Münzel, and Basma have disclosed no relevant financial relationships.

Eur Heart J. Published online November 20, 2020. Full text.

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