The only thing you can bring are maybe eye drops, but that really depends on the type of smog and your sensitivity. That will not change the effects of the smog though, only the symptoms.
The issue is that there are so many different types of smog, such as industrial, traffic, fire/smoke etc. Each of them occur in different locations and different height above street level.
So depending on the smog type, there are also different things you can do instead of equipment to have. For example stay away from smog sources (i.e. traffic), finding areas with less smog (in Hong Kong for example the smog in the south-east is much less than in the north-west), not doing any sports etc are things to observe.
Please note also that the effects of the smog are much more an issue for long-term exposure than when spending only a week there. Finally, people do not fall over dead in the street. You will most likely also be the only one with a N95 mask. People rather wear the surgical mask type, if anything at all.