Mario Osava* – Tierramérica
RIO DE JANEIRO, Feb 22 2010 (IPS) – Limiting your cholesterol through diet may not be enough to maintain cardiovascular health in polluted cities like São Paulo in Brazil: the particulates suspended in the air alter the molecular composition of LDL, popularly known as bad cholesterol, making it even more dangerous.
Polluted cities are a health risk, especially for the poor. Credit: Alejandro Arigón/IPS
The structure of LDL (low density lipoprotein) facilitates the accumulation of fat in the arteries, in other words, arteriosclerosis. This process ultimately restricts blood flow and can damage vital organs like the heart and brain.
The study that confirmed this risk is the doctoral thesis of biomedical scientist Sandra Castro Soares, of the University of São Paulo s medical school. The research was conducted using mice. But for the first time they were placed in the real environment, breathing the same air as humans, near a busy avenue in this densely populated city in southern Brazil.
One group of mice was exposed to smog on the streets, which comes mainly from vehicle exhaust, during their first four months of life equivalent to 40 human years. Another group of mice was kept in chambers with filtered air.
The first group ended the period with symptoms like thickened arterial walls, altered LDL, and production of antibodies to fight that change all of which are indicators of a higher risk of heart attack.
The problem lies with the microparticulates that cross the nasal and pulmonary barriers, entering the blood system, Soares explained in an interview with Tierramérica.
Related IPS Articles
They don t change the quantity of fat, but rather its quality of adhering to the artery walls, she said. The change attracts more antibodies, which in turn attract more LDL, in a vicious circle that aggravates the problem.
In the last few decades, São Paulo has cut in half the quantity of polluting particulates in the city air.
But the research revealed that even with the improvement, which meets the standard recommended by the World Health Organisation of less than 50 micrograms of particulate per cubic metre, the air is not clean enough, said Lucía García, who advised Soares on her thesis in the air pollution lab at the university.
The particulates are oxidants, and oxidised LDL intensifies arteriosclerosis, increasing vascular health risks for those who live in the world s big cities. Even exercising, such as jogging, in polluted areas can be very bad for your health, García said.
In fact, there are many recent studies in São Paulo that reveal numerous and varied effects of urban pollution: more girls are born than boys, there are more premature births and underweight newborns, male infertility is on the rise, and deaths from respiratory illnesses are increasing. Childhood cancer and hypothyroidism are other possible consequences.
Low birth weight is not just a matter of size, but means a less mature foetus, with organs that are not fully developed, which can lead to future health problems or premature death, according to Dr. Paulo Saldiva, who coordinates the University of São Paulo s (USP) air pollution lab.
The USP is today among the five universities in the world producing the most knowledge about the links between health and the environment, says Saldiva proudly, though he laments that the findings have had little influence on public policy in Brazil.
Air pollution as a serious public health matter has so far failed to mobilise the health authorities, who are more concerned about fighting infectious diseases like H1N1 influenza (swine flu), HIV/AIDS, and dengue, he said.
Furthermore, environmental officials and activists pay little attention to the relationship between the environment and human health, he added.
In contrast, the tobacco industry is apparently content with the conclusions about the effects of urban air pollution, because they can use them to play down the health effects of smoking, like lung cancer. But in any case, cigarettes are worse for your health than smog, the researcher stressed.
The problem is that while tobacco affects only those who decide to smoke or live with smokers, nobody can escape air pollution, Saldiva said. The poor are the most vulnerable to the risks because they travel for hours on buses on congested streets to get to their jobs, while the wealthy have their own enclosed cars with air conditioning, he pointed out.
Social inequalities compound other environmental injustices, given that the poorest of the poor live in unsuitable areas, vulnerable to floods and landslides, with a lack of clean water and heavy pollution, said Saldiva.
The situation is getting worse in São Paulo, where more cars are added each day to the six million vehicles circulating on the metropolitan area s streets. This slows down traffic and forces people to breathe the polluted air for longer periods, increasing the risk of contracting one of the many pollution related diseases, he said.
The USP air pollution lab research is focusing now on studying the effects on people who spend a great deal of time in the more polluted areas of São Paulo, such as traffic controllers at the busiest intersections.
Particulate matter and perhaps ozone are the elements of greatest concern in terms of urban health, said Saldiva.
(*This story was originally published by Latin American newspapers that are part of the Tierramérica network. Tierramérica is a specialised news service produced by IPS with the backing of the United Nations Development Programme, United Nations Environment Programme and the World Bank.)
