Word: heart
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Dates: during 2000-2009
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...near a local highway. People who breathed in polluted air registered higher blood-pressure readings a short time after exposure, compared with those who breathed filtered air, and their blood vessels showed impairment as long as 24 hours later. Such prolonged hypertension is a known risk factor for both heart disease and stroke. (Read "The Year in Medicine 2008: From...
...findings, published in the journal Hypertension, offers a potentially new understanding of how pollutants can affect the heart. While previous studies have linked bad air - specifically, air laden with fine particulates smaller than 2.5 microns in diameter - with higher rates of heart disease and stroke, it wasn't clear exactly how the particulates did their damage. Nor was it clear which of the many components of urban air were the most hazardous - the fine particulates from burning fossil fuels that come from exhaust pipes, or the ozone gases that permeate most densely packed city streets...
Brook's data suggest that particulates are more active players in heart problems than ozone, and that two different processes may be occurring as we inhale unclean air. First, the fine matter triggers changes in the central nervous system, causing a switch from the more controlled regulation of body processes to a more instinctive, automatic fight-or-flight response. This revs up the heartbeat and causes blood pressure to spike as the body may be responding to the presence of foreign, potentially dangerous particles in the air. (See pictures of the world's most polluted places...
...Particulates can lodge deep in the lungs, where they activate another process - inflammation, which kicks in over the 24 hours after exposure. The inflammatory response can stiffen blood vessels and cause longer-term damage to blood-vessel flexibility and their ability to absorb changes in blood flow from the heart. Weakened blood vessels can increase the risk of heart disease or stroke...
...that doesn't mean that every urban resident is at higher risk of heart disease. For most healthy people, the exposure to city air and transient changes in blood pressure isn't dangerous. But, says Brook, "it's plausible that if someone has underlying hypertension or coronary disease, then these changes in blood pressure and blood-vessel function might be exaggerated and might even trigger a heart attack. The levels at which we encounter these particles today is still dangerous to people who are unhealthy and at high risk." (See pictures of the effects of global warming...