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The Lead Pollution ReturnWood heating is reintroducing lead into the air of local communities and homes, according to a systematic investigation by academics from the University of Massachusetts Amherst. The research reveals that despite lead being banned as an additive in petrol more than 25 years ago due to its overwhelming neurotoxicity, the metal is now making a comeback through wood burning.Scientific FindingsThe research began by analyzing samples of particle pollution from five suburban and rural towns in the northeast US. Scientists looked for tiny particles of potassium that are emitted when wood is burned, as well as particles containing lead. Samples from seven winters revealed clear associations between potassium and lead - when there were more wood burning particles in a daily sample, there was more lead in the air."For the most part, wood burning produces significant amounts of particle air pollution, and a small but measurable fraction of this is a powerful neurotoxicant," said Prof Richard Peltier, the senior author of the research.Geographic PatternsThe project was extended to 22 other towns across the US, with the relationships between lead and potassium varying from place to place. The strongest associations were found in the Rocky Mountains. By factoring in temperature effects, the researchers strengthened their conclusion that the additional lead came specifically from wood burning.Health ImplicationsAlthough the lead concentrations found were less than US legal limits, health experts emphasize that any exposure to the metal is harmful. "The most logical answer is that it comes from uptake in the soil, probably riding along with the nutrients and water that trees need. Once in the tree, it deposits in the tree's tissues and remains until that tree is burned," explained Tricia Henegan, a PhD student at Umass Amherst and the first author on the research.Historical ContextLead was used globally as a petrol additive from the 1920s and found its way into oceans, soils and people. Evidence on harms from exposure to lead were systematically suppressed by industry for decades. Today it is acknowledged that lead exposure causes harm at all stages of life and comes from many sources.Policy RecommendationsThe researchers suggest that their findings challenge previous assumptions that lead in wood smoke came primarily from waste wood covered with old lead paint. "The use of wood as an energy source is a relic of the past, one that should not be relived if given a choice. Although wood fuel use can feel nostalgic, it does have negative consequences on air quality, and therefore public health," Henegan concluded.