China: Air pollution increases risk of cardiac arrhythmias – 05/14/2023 – Equilibrium and Health

Air pollution increases the risk of heart arrhythmias, according to a study conducted in more than 300 cities in China.

This risk is even greater in the first 24 hours after exposure to atmospheric pollution, but it decreases over time, also indicating that changing the environment to a less polluted place can help to recover from the damage.

The study used data from the Chinese Cardiovascular Association and was published on Monday (1st) in the specialized journal Cmaj (Canadian Medical Association Journal).

The research analyzed six different types of pollutants and the appearance of four types of condition associated with cardiac arrhythmias. Pollutant concentrations were analyzed in µg/m3 (micrograms per cubic meter) for the following compounds: nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), sulfur dioxide (SO2) and two types of materials particulates of size 2.5 (PM2.5) and 10 (PM10), which are found in the atmosphere and can cause damage to the lungs.

The WHO (World Health Organization) recommends a maximum concentration of 5 µg/m3 of PM2.5 pollutant and 15 µg/m3 of PM10 per day. For the others, adequate levels of air quality are considered to be 25 µg/m3 of NO2, 40 µg/m3 of SO2, 7 µg/m3 of CO and 100 µg/m3 of O3 (every 8 hours).

The average daily concentration of substances recorded was 34.4 µg/m3 (PM2.5), 25.5 µg/m3 (PM10), 27.5 µg/m3 (NO2), 8.9 µg/m3 (SO2) , 0.7 µg/m3 (CO) and 59 µg/m3 (O3).

The four types of primary arrhythmia included in the survey were atrial fibrillation (changes in the frequency of heartbeats), atrial flutter (similar to fibrillation, with the difference that it is less organized, with a more disconnected flow), premature beats (ventricular or atrial) and supraventricular tachycardia.

To assess the association between pollutants and cardiovascular symptoms, the authors compared 190,115 patients who had medical care for arrhythmias in 322 cities with other participants who did not have symptoms in the period from 2015 to 2021.

As the concentration of air pollutants also depends on meteorological conditions and the time of day (rush hour has a greater release of pollutants compared to the early morning period), the researchers recorded the time of onset of symptoms for each patient and compared them with data from the same time or day (up to three dice were used for each patient) who did not have a cardiac symptom.

For example, if a patient was admitted to a hospital at 7 am on November 9, the scientists used data from patients on November 16, 23, and 30 at the same time (7 am) as control groups.

In total, the following were recorded:

• 96,133 cases of atrial fibrillation;
• 5,300 of atrial flutter;
• 41,613 premature beats;
• 47,069 of supraventricular tachycardia in the period.

The risk of developing arrhythmias in relation to exposure to pollutants NO2, SO2 and CO was the highest, with an increase in the incidence of 1.7% to 3.4% of atrial fibrillation, 8.1% to 11.4% of flutter atrial and 3.4% to 8.9% of supraventricular tachycardia.

Exposure to both PM2.5 and PM10 particulate matter was associated with a significantly higher incidence of atrial flutter (8.7%) and supraventricular tachycardia (8.7%), while ozone was associated with a higher risk of tachycardia (3, 4%). There was no significant association between premature heartbeats and exposure to pollutants.

However, it was NO2 that had the greatest association with arrhythmias, proving to be the most harmful pollutant to the heart. It is one of the main pollutants eliminated with the burning of fossil fuels, and it is highly toxic. The association of this pollutant with atrial flutter, for example, reached almost a 20% increase in risk, a condition that, although rarer, can lead to more serious heart conditions.

In conclusion, the authors state that, although the study was conducted in China, where exposure to air pollutants is very high, the research data can be extrapolated to other places and countries, since there was no “threshold” of exposure that would make the risk of developing arrhythmias safe.

Recently, research carried out by researchers from Brazil, Mexico and the United States found a greater association of respiratory and cardiac diseases after fires in indigenous territories in the Legal Amazon region of Brazil. Pollutants released from fires cause 15 million cases of respiratory and heart disease each year.

The incidence was also higher in the first 24 hours of exposure to pollutants, which puts proximity to atmospheric toxic gases as a high health risk.

Thus, the authors say that even though the magnitude of symptoms may vary in relation to the type of pollutant and exposure, the study provides evidence of the adverse side effects of air pollution on the heart and how this exposure affects global health.