 Endotoxin is a component of outdoor air pollution, an air contaminant found in a number of different workplaces, and is even found in homes. The endotoxin used for this study is obtained from the National Institutes of Health, and is called Clinical Center Reference Endotoxin, or CCRE. The purpose of this Phase 1 research study is to identify a dose of inhaled endotoxin that is safe does not cause prolonged cough, shortness of breath or other problems, but causes changes in your sputum cell samples that the scientists can measure. Phase 1 research studies like this one are not intended to be a treatment, but are a scientific investigation. Eventually, with these types of studies we will be able to examine why some people are more sensitive to endotoxin. Scientists at other universities have found that while most people do not have a considerable lung response to endotoxin at doses as high as 60,000 EU endotoxin units, a few respond to as little as a total dose of 4500 EU. Our study is designed to identify if using a dose of 20,000 EU causes changes in the lung cells but does not cause symptoms in our study subjects. In our previous studies in our lab, using an endotoxin from another source, we have used higher doses 15,000 EUs in subjects with asthma with no major problems, and we have used 10,000 EUs of CCRE in subjects with allergies and asthma without problems. We have used 20,000 EUs of CCRE in healthy individuals with no major problems. 