Dilema: people say diesel polutes air but no smog for diesel car

Isn't it interesting? One side people say diesel cars polute air quality more than gas engine ones, but as we all know, California has the most stringent air emission standard in US, but diesel cars are not required to go smog tests.

I have 3 diesel cars - full house of diesels but no gas... I don't need to go smog tests at all. Every year, when a car registration is due, I receive a letter noticing me for registration but no emission test is required. I just log on to DMV website and pay the registration fee. A few days later I receive the tag. That is it.

The same non-smog-test-required is for electric hybrid cars, too. Does that mean diesel cars have the same polution level than hybrids? Correct me if I am wrong.