The sensitivity of potassium iodide starch paper

I have some questions about the sensitivity of potassium iodide starch paper.


Patients with asthma caused by allergic airway inflammation have high levels of nitric oxide ($\ce{NO}$) in exhaled breath. This is usually measured with chemiluminescence analyzers by measuring the light generated by a chemical reaction of $\ce{NO}$ with ozone. This technique has high sensitivity, and NO can be accurately measured in the parts per billion (ppb) range. 


This above method requires a complicated apparatus.


I am now considering an alternative method.


When NO is exposed to oxygen, it is converted into nitrogen dioxide:


$$
\ce{NO + O2 \rightarrow 2 NO2}
$$


When wet potassium iodide starch paper is exposed to an oxidizing gas, such as $\ce{NO2}$, its color changes to purple or blue. The intensity of the color depends on the concentration of the oxidizer.


**My questions are:** 


* If, at room temperature, 1 litre of exhaled air is enclosed in a container, inside of which a wet potassium iodide starch paper is placed, would that paper ever get a blue tint if the NO concentration in the exhaled air is only 25 ppb (parts per billion)?
* How long would it take?
* Would it help if the volume was bigger, for example 10 litres?
* Could one improve the sensitivity in some simple way?


