@pssurfer and @taya There is a copy of the saline chart floating around this group (I will have to search for mine if nobody else posts it) NIH did a study and it proved that the 7% saline actually kills the mac, the 3% is not strong enough. The chart shows which percentages of saline strength kills which bacteria types and other pathogens. I believe that some drs are just unaware of this and some people have printed the chart and article to take and show their physician. Some patient's lungs are too fragile due to history of pulmonary ebolisms (blood clots in the lungs), or from cavities in the lungs. It is good to ask your dr WHY you are being limited to 3% saline. For some of us, we need the 7% strength to adequately agitate the lungs to produce the desired cough to bring the gunk up. For others still battling mac infection; it helps to kill down the mac.