New nebulizer equipped with Selector M. The selector M uses the surface pressure and liquid gravity to reduce by a factor 2 the drug loss from nebulizer. The selector M enables to reduce drug dumping in the atmosphere by using droplet impact principle in nebulizer. Inhaling phase: - Aerosol is produced by air decompression, - Smallest particles are selected, - Patient inhaled air improve aerosol production: breath enhanced nebulizer, - Biggest accumulated particles are recycled at selector M bottom. Exhalation phase: - Exhausted particles in nebulizer are speeded up in selector M, - Biggest particles return directly to liquid stage, - The light fraction only is rejected out of the nebulizer. Approved by: - ASTRA FRANCE for PULMICORT-SUSPENSION - ROCHE GENENTECH pour PULMOZYME connected to the compressor ref. AL.