Nanometer soot maybe worse for diesel emissions

Today comes the news that DUSTLESSNESS INCREASES POLLUTION:

http://www.bbc.com/news/science-environment-39895558

I wonder if the environmentalist drive to reduce the size of soot particles makes also pollution worse in European cities, in other words: large size soot particles may be better for the air than smaller size soot particles.

By the way, our lungs can filter out particles as small as 5 micrometers, but not smaller than that, which is what our new Ad-Blue technology diesels produce:

OK, so there's a couple things going on here, and I feel that I need to address them separately.

TDI2000Zim said:

Today comes the news that DUSTLESSNESS INCREASES POLLUTION:
http://www.bbc.com/news/science-environment-39895558

Click to expand...

Note that the dust blowing in from the Gobi desert has a significantly different health and environmental impact than diesel PM10.

On the health front, diesel PM10 is carcinogenic, and AFAIK in far lower concentrations than the dust concentrations that would cause silicosis and cancer from that.

On the environmental front, diesel PM10 is black, which means that it'll absorb light and cause warming, unlike the light-colored dust, which will reflect light and reduce warming.

TDI2000Zim said:

I wonder if the environmentalist drive to reduce the size of soot particles makes also pollution worse in European cities, in other words: large size soot particles may be better for the air than smaller size soot particles.
By the way, our lungs can filter out particles as small as 5 micrometers, but not smaller than that, which is what our new Ad-Blue technology diesels produce:

INVISIBLE TO THE EYE NANOMETER SIZE SOOT​

Click to expand...

The movement is not to reduce the size of soot particles, it's to reduce overall particle mass, and a functioning DPF does that effectively without increasing particle count (so particles are eliminated, not divided). However, gasoline direct injection engines have big problems with high PM2.5 emissions... which regulators have become aware of, and are responding to.

Actually, it has been shown that DPF is especially effective in reducing nanoparticles in diesel engine exhaust to background levels:

...Due to the overlapping filtration mechanisms, both large as well as small particles can be held back reliably, thus achieving a filtering efficiency of nearly 100% across the entire spectrum of sizes...

...Since the diffusion speed increases with decreasing particle size, smaller particles are actually separated the most effectively....

Click to expand...

Fiebig et al., "Particulate emissions from diesel engines: correlation between engine technology and emissions." Journal of Occupational Medicine and Toxicology, 2014, 9:6, http://www.occup-med.com/content/pdf/1745-6673-9-6.pdf [Page 8 of 18, emphasis added]