The environment is like a normal city, or like New York City like if is right now in current times. The weather is sunny and it takes place in either fall or spring because Daniel and Natasha are both in school. I would imagine it to have lots of cities, not a lot of land that is not occupied unless they are doing construction or something that is similar to it. Also, it would have lots of streets, cars, and mostly people.
The setting of this book changes the feel and the whole story because without many of the modern day technology, Daniel and Natasha wouldn't meet, and the story would not come together because they will never meet. So it affects it because the subway has led Daniel to Natasha, the car made Daniel save Natasha, and if they didn't have phones, they would be able to ask each other questions. So if there were no modern day technology, the whole story would be different.