publicado em 25/04/2013 às 12h47:00
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Cardiovascular control professionals transit is affected by pollution

Contact with pollution from traffic leads workers to submit changes in your heart rate at rest

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Study evaluated the effect of pollution on heart rate variability of taxi drivers and traffic controllers in the city of São Paulo. More in touch with the pollution that ordinary citizens, workers have traffic changes in your heart rate at rest, in response to small changes in the concentrations of pollutants in the air.

According to the physiotherapist Daniel Antunes Alveno, author of the research, the finding surprising, considering the chronic exposure of taxi drivers and traffic controllers to pollution. In those less exposed, the effects of pollution are felt only during exercise. Developed at the Hospital das Clinicas (HC), Faculty of Medicine, USP (USP), the study sought to understand how pollution acts on the cardiovascular system of these workers.

The study considered data from 75 people selected for screening at the HC. Of these, 57 belonged to the group of workers from the traffic and the other 18, constituting a sort of control group, were employees of the Horto Florestal de São Paulo, located more than 12 kilometers (km) from the city center. Participants were evaluated four consecutively within a month, one per week, on different days of the week.

The day before the assessment, professionals should seek a gauge of pollution that would be with them for 24 hours, to be collected pollution to which they were exposed in the most close to the real Alveno reports. The next day, workers gave back the unit for analysis and passed an assessment of your heart rate into two phases: rest and exercise, moments ways controlled by a different part of the nervous system called the autonomic nervous system (ANS), responsible for regulating the involuntary functions of the body, including the heartbeat.

The ANS is divided into two other systems with antagonistic functions: the sympathetic nervous system (SNS), which stimulates the body's responses to stress, including exercise, accelerates breathing and heartbeat, increases the concentrations of adrenaline and sugar in the body and activates the general metabolism of the body, and the Parasympathetic Nervous System (PNS), which takes account of the activities that respond to situations calm, slows heart and breathing, lowers blood pressure, adrenaline and blood sugar.

The interaction and balance of the two systems can be analyzed by a component called heart rate variability (HRV), which measures the difference between the frequencies of the beats in the sympathetic and parasympathetic nervous stimuli. The ideal scenario, which indicates a person with a healthy cardiovascular system, is the high HRV. In turn, the reduction in HRV, with prevalence of the NHS over the SNP, indicates alteration of autonomic functions of the body, either internal or external agents.

Workers traffic had a reduction of parasympathetic nerve activity during rest, says the researcher. The first response would be expected that these professionals have one ning the functioning of the sympathetic system. But as they already have a high level of stress, the answer is to reduce the parasympathetic complete. With the increasing levels of pollution, the effects are even more acute.

In turn, employees Horto exposed to less than half the pollution that the other group is subjected to daily have reduced parasympathetic only during exercise, when subjected to a cardiovascular stress, while also presenting the prevalence of the activities of the NHS during the rest. This prevalence of SNS even in the group of forest workers occurs because, despite being exposed to a smaller amount of pollutants than the other group, they are still subject to significant amounts of pollution above the level recommended by the World Health Organization (WHO) low cardiovascular risk (10 micrograms per cubic meter of air).

Decreased HRV, says the researcher, does not indicate the presence of disease. The heart rate variability is a physiological response to this increase in pollution, says. However, the study data showed that as people with hypertension, diabetes, obesity, and they appear in large numbers in the population, correspond exactly to the group that had more intense response to the increased concentration of pollutants. It is not known if the pollution is causing or aggravating agent but who is very exposed to it may have a greater tendency to increase and worsening of these diseases, assesses the physiotherapist.

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Cardiovascular control    heart rate variability    pollution    heart rate    Hospital das Clinicas    Faculty of Medicine    USP    Horto Florestal de São Paulo   
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