The wildfire smoke that has blanketed Michigan in the United States this month could take a toll on health long after clearing.
The particles that form plumes of wildfire smoke are small (the average human hair is at least 30 times larger). That means they can seep into our blood, where they pose a triple threat to our lungs, hearts and brains, medical researchers say.
Doctors and medical researchers have known for decades that air pollution is lixed to early death, said Sara Adar, a University of Michigan epidemiology professor and associate editor at the journal Environmental Health Perspectives.
From there, they discovered that air pollution hurts the respiratory and circulatory systems.
The US Centre for Disease Control and Prevention says particulate matter exposure can cause coughing, difficulty breathing, irregular heartbeats, asthma attacks and more.
Within the past decade, the pollutant has also been lixed to affecting brain function, Adar said.

本月席卷美国密歇根州的野火烟雾，即使在消散后，仍可能对健康造成长期影响。
医学研究人员表示，形成野火烟雾的颗粒物非常微小（平均来说，人类头发的直径至少是它们的30倍）。这意味着它们可以渗入血液，并对我们的肺部、心脏和大脑构成三重威胁。
密歇根大学流行病学教授、期刊《环境健康视角》副主编Sara Adar表示，医生和医学研究人员几十年来就已经知道空气污染与早死有关。由此，他们发现空气污染会损害呼吸系统和循环系统。
美国疾病控制与预防中心表示，暴露于颗粒物可能导致咳嗽、呼吸困难、心律不齐、哮喘发作等问题。
Adar说，在过去十年里，这种污染物还被发现会影响大脑功能。

“Our brains are incredibly sensitive to how much oxygen we get, the pumping of the blood,” she said. “Anything that’s going to damage the blood vessels, which is part of what causes heart disease … is going to damage the brain as well.”
The connection is getting renewed attention as Michigan forecasters have issued more air quality warnings because of wildfire smoke this summer than at any time in at least 26 years.
Further research into the role wildfires play in brain health will also be important going forward, as human-caused climate change intensifies droughts and amplifies wildfires, particularly in northern regions like Canada, according to the National Aeronautics and Space Administration.
Wildfires are, though, a problem in many other parts of the world too. Firefighters have contained a massive wildfire in southern France but officials there warned on Sunday that scorching heat and dry conditions could reignite the blaze, as parts of the Mediterranean region face a heatwave.

“我们的大脑对获得的氧气量、血液的流动极其敏感，”她说，“任何会损伤血管的因素——而这也是导致心脏病的部分原因，同样也会损伤大脑。”
随着密歇根州气象部门因野火烟雾发出比过去至少26年来更多的空气质量警告，这一联系再次受到关注。
美国国家航空航天局表示，随着人为引起的气候变化加剧干旱并加剧野火，尤其是在加拿大等北方地区，未来对野火对大脑健康影响的进一步研究也很重要。
不过，野火在世界许多其他地方同样是个问题。法国南部一场大规模野火已被消防员控制，但当地官员周日警告说，酷热和干燥的环境可能会让火势重新燃起，因为地中海部分地区正面临热浪。

The fire has ravaged a vast area of France’s southern Aude department at the peak of the summer tourist season, killing one person and injuring several others. Authorities said that hot, dry winds on Sunday and a heatwave would make the work of firefighters more difficult.
In Greece, emergency services brought numerous fires under control over the weekend, but new outbreaks are likely due to a lasting drought and strong winds, officials said on Sunday.
Jonathan Overpeck, dean of the School for Environment and Sustainability at the University of Michigan, said the issue was “a climate change problem, no doubt about that” and said that “we’re paying the price. As long as we keep making it hotter and drier by burning fossil fuels, we’re going to keep making this situation worse”.
Last month, a team of researchers published a review of recent medical studies that show long-term exposure to small particle pollution known as PM 2.5 can increase a person’s risk of developing dementia.

这场大火在夏季旅游高峰期席卷了法国南部奥德省的大片地区，造成一人死亡，数人受伤。有关部门表示，周日的炎热干燥大风和热浪将使消防员的工作更加艰难。
希腊紧急服务部门在周末控制了多处火灾，但官员周日表示，由于持续干旱和强风，新的火灾很可能再次爆发。
密歇根大学环境与可持续发展学院院长Jonathan Overpeck表示，这“毫无疑问是一个气候变化问题”，“我们正在为此付出代价。只要我们继续燃烧化石燃料，让气温变得更高、更干燥，这种情况只会变得更糟。”
上个月，一组研究人员发表了一项最新医学研究综述，显示长期暴露于被称为PM2.5的细颗粒物污染会增加患痴呆症的风险。

While exposure from any source of fine particle pollution was associated with greater rates of dementia, the lix is particularly strong when those particles come from wildfire smoke and agriculture, according to a 2023 investigation Adar co-wrote in the journal JAMA Internal Medicine.
The researchers used data from a health survey of nearly 28,000 people who were part of a study between 1998 and 2016.
Participants were surveyed on their cognitive health, overall health and behaviours until they died or stopped taking part in the survey. Researchers only used data from people who did not have dementia at the time of their first interview.
They then reviewed the estimated amount of PM 2.5 the participants would have been exposed to at their home addresses over time, looking at the total amount of particle pollution and particle pollution from nine different sources, including road traffic, coal-fired power plants, wildfires, and more.

Adar在2023年与他人共同撰写并发表在《美国医学会杂志·内科学》上的一项研究指出，虽然任何来源的细颗粒物污染都会与较高的痴呆症发病率相关，但当这些颗粒来自野火和农业时，这种联系尤其紧密。
研究人员利用了1998年至2016年间近28,000名参与者的健康调查数据。参与者被调查认知健康、整体健康状况和行为，直到去世或退出调查。研究人员只使用了首次访谈时尚未患有痴呆症的人的数据。
随后，他们回顾了参与者在家中可能接触到的PM2.5的估算量，考察了颗粒物污染总量及来自包括道路交通、燃煤电厂、野火等九种不同来源的颗粒物污染。

Based on the results, the researchers estimated nearly 188,000 new cases per year of dementia were attributable to total PM2.5 exposure in the US.
The researchers did not determine why particles from wildfires and agriculture appear more closely lixed to dementia, but Adar said they have several guesses.
Agricultural particles likely carry neurotoxic chemicals in pesticides and herbicides, which could affect the health and brain function of people who live nearby, she said.
Wildfire smoke tends to be very concentrated compared with other sources of pollution, which might increase its lix to dementia, Adar said. It can also blanket areas for days at a time, like it recently did in Michigan.

根据结果，研究人员估算，美国每年有近188,000例新发痴呆症可以归因于总的PM2.5暴露。
研究人员并未确定为何来自野火和农业的颗粒物与痴呆症的关联更为密切，但Adar表示他们有一些猜测。她说，农业颗粒物可能携带农药和除草剂中的神经毒性化学物质，从而影响附近居民的健康和大脑功能。野火烟雾相比其他污染源更为浓烈，这可能加剧其与痴呆症的联系。野火烟雾还常常像最近在密歇根一样在某地持续数天。

It is not just trees and vegetation that burn when wildfires rage.
“You’re talking about burning gas stations and homes and cars, all of which are putting a toxic soup into the air,” Adar said.
That toxic soup has been on the menu for a long time this summer.
As of Wednesday, there had been 21 days this summer when the Michigan Department of Environment Great Lakes and Energy meteorologists issued air quality warnings for parts or all of Michigan.
The only comparable year is 2023, when Canadian wildfire smoke collected in Michigan and caused skyrocketing levels of pollution and a thick haze that hung low over Detroit. The pollution was stronger that year, but it did not last as long, said Jim Haywood, EGLE senior meteorologist.

野火肆虐时，燃烧的可不只是树木和植被。
“你要知道，油站、房屋、汽车也在燃烧，这些都会向空气中释放大量有毒混合物，”Adar说。
这个夏天，这种有毒混合物一直在空气中徘徊。截至周三，今年夏天密歇根环境大湖与能源部的气象学家已经为密歇根部分或全部地区发布了21次空气质量警告。
唯一可比的是2023年，当时加拿大野火烟雾云集密歇根，导致污染水平飙升，底特律上空出现了持续低悬的浓雾。EGLE高级气象学家Jim Haywood表示，那一年污染更严重，但持续时间不如今年长。