I'm not sure if that's true, but if it is then electric cars will definitely reduce the problem. They use regenerative braking for a large percentage of their braking power, which means that the brake pads are used much less.

NOx completely comes from combustion, fine particles both from combustion and brake pad dust and tires. The fine particle load is greatly reduced by going electric, one has also to take into respect, that the fine particles from combustion are much smaller and consequently more dangerous than brake and tire dust.