Author Topic: Nano-particles may be more dangers than PM2.5  (Read 362 times)

ergophobe

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Nano-particles may be more dangers than PM2.5
« on: November 22, 2019, 06:10:39 PM »
And almost nobody is measuring them

https://www.bbc.com/future/article/20191113-the-toxic-killers-in-our-air-too-small-to-see

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“I expected a certain level of variation [in particle number]”, she says, “but the level of fluctuation really surprised me… The volume of cars that went past had very little impact on people’s exposure to PM2.5. But it had a massive impact on ultrafines.” As the volunteers pounded the pavements, they were exposed to a minimum of 36,000 particles at a time, up to a maximum of 130,000. When they took the same route by bicycle (tricky, but not impossible, with all the equipment), the maximums and minimums went up by another 20,000.

However, the highest averages were recorded inside the cars and buses: the closer to the source of the pollution, the exhaust pipes spewing out the fumes, the higher the total number of nanoparticles. The difference between walking by the kerbside of the road, and by the building side, on the same pavement – just a few short steps – was an average of 82,000 particles versus 69,000. The same readings registered no change in PM2.5.

ergophobe

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Re: Nano-particles may be more dangers than PM2.5
« Reply #1 on: November 22, 2019, 06:13:11 PM »
Fascinating article...
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A machine borrowed from the Netherlands used electrodes to scatter gold into nanoparticles right down to 2nm in size. First, the Edinburgh team got mice to breathe in the gold nanoparticles; next, it was the human volunteers’ turn. “We used gold because we know it is really safe”, explains Raftis, reassuringly. “It is used clinically because it is inert, it doesn’t react to things or cause oxidative stress in the body.” It is also easy to detect, unlike carbon particles which are effectively camouflaged within our carbon-based bodies.

The volunteers gave blood and urine samples 15 minutes and 24 hours after they inhaled the particles. Lo and behold, there was gold in them there samples. The team discovered a 30nm cut-off point; anything below that could be found swimming around in the bloodstream, but anything above that failed to get past the lungs.

“Obviously with humans we couldn’t perform a biopsy, but with the mice we did”, says Raftis. “We found the biggest accumulations [of particles] in the lungs primarily, but the liver next, because your liver is where the blood passes through first… the pore size in the kidney is 5nm, so nothing bigger than that would pass through the kidney… There could be accumulations in other parts of the body as well, because pore sizes across the body differ.” Gold was still present in the urine of the volunteers three months later.