Worldwide Stationary Oxygen Concentrator markets have been transformed by new units that are  lightwieght, feature quiet operation, and are very sturdy.  The smaller units are lightweight, and easy to transport. 
 
Oxygen Concentrators are ued by people with compromised lungs, particularily people who smoke,    Philips Respironics has been able to build enormous credibility in the market. 
 
Stationary oxygen concentrator vendors have seen a significant increase in demand in these specific markets with lots of air pollution.