Ultrafine particles are killing us, and most of us have never even heard of them.

They come from burning stuff, primarily diesel and gasoline in vehicles.

Gardiner Expressway on a June Sunday morning/ Lloyd Alter

I often do the annual charity bike ride on Toronto’s Gardiner Expressway and wonder what idiots thought it was a good idea to allow glass apartments hanging over a highway that is filled with idling cars and trucks most of the time and screeching stunt drivers for the balance. These people probably get one morning a year when they can use their balconies, and that’s when the bikes take over. The rest of the time they are sucking exhaust fumes and particulates.

I have also often written about the dangers of PM2.5 (particulate matter smaller than 2.5 microns) most recently in Particulate Pollution Is Worse Than We Knew, and Is Damaging ‘Every Organ in the Body’ Now new research looks at the dangers of a subset of PM2.5, Ultrafine Particles (UFP) which are PM0.1 or less than a tenth of a micron, or 100 nanometers. Scott Weichenthal, an Associate Professor in McGill’s Department of Epidemiology, Biostatistics, and Occupational Health, describes them:

“Ultrafine particles are incredibly small, allowing them to penetrate deep into the lungs and enter the bloodstream. Increasing evidence suggests these pollutants may contribute to heart and lung diseases, as well as certain forms of cancer."

Weichenthal was principal investigator in a study, Airborne Nanoparticle Concentrations Are Associated with Increased Mortality Risk in Canada’s Two Largest Cities- Toronto and Montreal. It concluded that “long-term exposure to UFPs with a 7.3 per cent increase in the risk of non-accidental death. Respiratory deaths saw the highest increase, at 17.4 per cent, followed by a 9.4 per cent rise in deaths from coronary artery disease.” That’s 1,100 deaths per year in the two cities. It is likely that the DALYs, or years lost of healthy life, could be many times that. (For more on DALYs, see Burning stuff is depriving us of years of healthy living.)

UFPs can come from many sources; Weichenthal suggests that these come from burning fossil fuels, telling the Toronto Star: “Anytime you burn anything, it could be gasoline, it could be diesel, anytime you’re burning an organic material, you are increasing these particles.”

According to the McGill press release,

The researchers said environmental regulations have successfully reduced air pollution in North America, but ultrafine particles are slipping through the regulatory cracks. In New York, UFP levels have risen, even as PM2.5 levels dropped. "Our research shows a clear link between long-term UFP exposures and increased mortality risk, underscoring the urgent need for regulatory actions targeting these particles,” said Weichenthal. “As urban areas continue to grow, addressing air pollution is increasingly crucial for the health and well-being of city dwellers.”

UFPs are included in PM2.5 and might well make up most of it, but have never been regulated separately. I will confess that they were not even on my radar until I read the Star article. Of course, the Europeans are onto this already, with the European Commission funding the RI-URBANS project focusing “on human exposure to outdoor ambient nanoparticles (in number concentration) and atmospheric particulate matter (PM, in mass concentration) in terms of their sizes and constituents, as well as their source contributions and gaseous precursors.” They note two main sources: road traffic and “photochemical nucleation” from precursor gaseous pollutants which react with ultraviolet light. They suggest that the smaller the particle, the worse the danger:

“Epidemiological and toxicological studies suggest that negative health effects may increase with exposure to decreasing particle size. Due to its nanometric size, inhaled ultrafine particles are uptaken by epithelial cells in the lungs where they can even penetrate the tissue. They can also be translocated to the interstitial space that lies in between blood vessels or can reach directly the bloodstream, making it more difficult for its removal from the body.”

Going down the photochemical nucleation rabbit hole, one finds that cleaning up the bigger particulates like PM2.5 increases the creation of the smaller ones, since the car exhaust gases get exposed to more UV radiation. “Our results imply that reduction of primary particles or removal of existing particles without simultaneously limiting organics from automobile emissions is ineffective and can even exacerbate this problem.”

We live in such a crazy world. It become more evident every day that particulates are killing us. Yet we are barraged with ads promoting the burning of fossil fuels in our kitchens and in our cars.

Now we are learning about the dangers of ultrafine particles. Who know how many healthy years have been lost or how many billions of medical costs have been incurred because of them, all because we love burning stuff.

NOTE: I have turned off comments because they are diverging from the subject and getting way too political and confrontational for me. I want this to be a happy place!