Cardiac fibrosis related to prolonged black carbon exposure

A study by researchers from the University of São Paulo (USP) has found that long-term exposure to air pollution is directly linked to increased heart risks in residents of that city and that people with high blood pressure (aka Hypertension) are at even greater risk.

Specifically, the research revealed that that cardiac fibrosis, an indicator of heart disease, is related to the duration of exposure to black carbon particles.

The team examined the autopsies of 238 people and interviewed relatives of the victims to gather information on risk factors such as a history of smoking and hypertension. From macroscopic observation of lung tissue, they determined the presence and amount of the black carbon in the lungs, while samples revealed the cardiac fibrosis.

The results showed a significant association between the amount of black carbon in the lungs and cardiac fibrosis in the individuals studied. This means that the longer a person is exposed to pollution, the more likely they are to develop fibrosis. 

Paulo Saldiva, one of the authors of the study, pathologist and USP professor said: ‘This data highlights the crucial role of autopsy in investigating the effects of the urban environment and personal habits in determining diseases.’

It was also found that the risk increased for people with high blood pressure. Among them, the presence of the heart disease marker (an indication that disease may develop) increases with the increase in exposure to air pollution, both for smokers and non-smokers. Among those without high blood pressure, the highest risks were observed mainly among smokers.

Over the ten years between 2011 and 2021, the mortality rate from hypertension in Brazil increased from 11.8 deaths per 100,000 to 18.7, with around 60% of the country’s elderly suffering from it.

The researchers point out that hypertension is silent and pollution is not always visible but exposure to pollution can be mitigated to a certain extent.

Saldiva said: ‘We can say that there are two indicators of pollution, one measured by the CETESB* network, which is objective. And another related to how much each individual is exposed to. In other words, the level of concentration of environmental pollution doesn’t mean the same dose is received by everyone. If you’re in a traffic corridor for hours, you receive a higher dose because the concentration of that environment is particularly higher.’

Saldiva explains that various factors, such as hypertension itself, influence the development of cardiac fibrosis, and that pollution has now been shown to be one of them. ‘The question was, “Is pollution big enough to show up in this photo?” It is, and it was the first time in the world that it had been demonstrated in humans. That’s the difference in this work.’

The full research can be obtained here.

* São Paulo State Environmental Corporation