A few questions about EXHAUST related symptoms...???

I just recently began driving a rather old and beat-up ice cream truck
and lately I have been having some headaches. This truck, which is due
for inspection in a few months and uses gasoline as fuel doesn't run
too well.

Here are a few questions.....

Can you be adversely affected by fumes in a vehicle that has it's
windows open and numerous holes throughout the body of the truck? I
always keep the windows open and the truck is far from airtight.

Thanks

LT