I have an older diesel VW. It is extremely common for people to run tunes that disable the check engine light that is produced when you delete the exhaust gas recirculation valve (EGR), urea pump and diesel particulate filter (DPF).

For things like the EGR, blocking it off is simply installing a bracket or two and closing off some vacuum lines. I can imagine people would simply reinstall this and swap the tune to pass and then immediately remove it after.

In the US, for emissions, all you have to do is not run any check engine lights when at the test center which is easy to do in the software tune.

> In the US, for emissions, all you have to do is not run any check engine lights when at the test center which is easy to do in the software tune.

Which is very disappointing...

When I first moved to Arizona I had a '67 Galaxy and that thing got to run on the dyno in the emissions office but when I got my truck to replace it (not having AC in Arizona isn't fun) all they did was plug in into the computer and charge me more for the test.

My (carburated) motorcycle was in between, they couldn't run it on the dyno and couldn't plug a computer into it so just tested it at idle -- which seemed pretty pointless to me, even being all hopped-up it still got better gas mileage than most cars on the road, though it did get pretty horrible gas mileage for a motorcycle considering I had to run premium in it.

In Spain we have a similar exam and unfortunately I know that there are indeed people that cheat. I don't know the details but there are ways to make their car emit less smoke only that day, and then go back to "normal".

Probably we should do as many Asians do in this, and make it normal to go out with a face mask.

Not sure what kind of masks have to be used to effectively not breathe pollution, and their effectivity, though. Getting informed about that is in my to-do list.

no mask can filter particles

Filtering airborne particulates is pretty much the baseline reason to use masks ¯\_(ツ)_/¯

(However surgical masks aren't meant to do that, they're only meant to catch things expelled from you, not the other way around. So I guess your interjection is somewhat correct in that running around with a surgical mask does pretty much nil to improve the quality of the air you inhale.)

Doctors also have masks to protect them from external things (for example, when they deal with patients that have tuberculosis), although I've just learned from Google that they are not technically called masks, but respirators (N95 respirators).

They are quite uncomfortable to wear, though. You can breathe just fine for extended period of time but it feels (at least to me, a layman in these things) like you get less air. I wouldn't wear it as an everyday thing.

I have no idea if there are more comfortable solutions that can handle pollution.

I'm a hobbyist woodworker and so I wear a half-mask with either a simple flat P3R filter [1] or a bigger A2P3R filter stack [2] a lot when doing that. When it's hot it is a bit annoying that sweat and moisture tends to condense in the mask. Another annoying thing is that these kind of masks tend to put pressure on the nasal bridge which gives you similar issues like a poorly adjusted pair of glasses. This is a larger problem with the filter stack because it is much heavier than the flat filters.

As for efficiency, I found a paper (DGUV IFA 0233) saying standard P3 particle filters are highly efficient even against ultrafine aerosol particles (particle diameter below 100 nm); for "larger" stuff (PM1 and larger) these are specified to remove more than 99.9 % of them.

This actually leads to P3 filters already removing a lot of smells, e.g. when you machine steel or wood, sand wood or grind steel, you don't smell it. However, gaseous stuff like solvents get through. That's what the A2 filter is for.

[1] https://asset.conrad.com/media10/isa/160267/c1/-/de/831230_A...

[2] https://assets.tooler.de/cimage/700x700/media/catalog/produc... [note: outer particle filter isn't installed in this picture, it would go under the translucent hood and is about the size of a Leibniz keks [3]

[3] https://en.wikipedia.org/wiki/Leibniz-Keks

I've worked in one and I got used to it, wearing it for an hour at a time for 4-5 hours per day. For comfort, a positive pressure air purifying respirator (PAPR) is preferable but looks like you're on a biohazard scene.

Do you have any link or description of such a mask?