How much does inside the city affect children with asthma?

It depends...: Assuming you mean "living inside the city" the answer would depend on the city's air quality. Air pollution can be a trigger for an asthma exacerbation, so living in a city with poor air quality can cause problems in an asthmatic child.

A lot: Pollution, car/diesel fumes, dust, smoke all can exacerbate asthma, especially when repeatedly exposed. Same goes for rented apartments where you can't get rid of carpeting, shades etc that collect dust and mold. Unfortunately, sometimes you don't have a choice. See your doctor for a more comprehensive list of what your child should avoid. Good luck!