Unfortunately in many countries (including the US) it's illegal to sell lung as a food product, because there's a risk that gastrointestinal juices might leak into the lung during the butchering process. The risk is very small, but eating a contaminated lung can make you very sick, so a lot of countries have banned it.
Also, half of the samples collected were found to contain physical contamination within the airways of the lungs. These results suggest that pork lungs are not safe and should not be saved for human consumption.