At https://www.petrolprices.com/drivers-breathe-9-times-more-pollution/ I came across an interesting item. This was my response:
The results of this finding are not really new. Twenty years ago research showed that drivers were more at risk from exposure to pollution than those alongside the road (although those exercising, eg. joggers and cyclists, were also at higher risk). Height was also a factor in exposure as has been written here.
Therefore, as someone suggested above, using air conditioning with the settings on 'recirculate' will help - certainly with particulates (pollen, diesel fumes etc) - if not with actual gases which will be unaffected by filters.
Other than this, completely close all air admitted to the vehicle or have your windows only slightly open.
What is really needed is for car ventilation to be admitted high up (top corners of the windscreen?) rather than low down through the grill, as is almost universal now.
This needs to change.