Is the extraction capacity of your extractor hood not sufficient?
Extraction to the outside
The exhaust duct has a big influence on the extraction capacity of an extractor hood. Every 90-degree bend reduces the extraction capacity by about 10%. As time goes by, grease build-up can cause the blades of the exhaust grid to get stuck. Dust, or even a bird's nest, can also obstruct the exhaust. Grease filters must be kept clean. See "Grease filter maintenance" for more information.
Recirculation
Recirculation with charcoal filters generally results in a 20-30% reduction in extraction power. Make sure to replace the charcoal filters every 4-6 months. With longer use, grease build-up will reduce the extraction capacity. A more effective and energy-efficient way is recirculation in combination with plasma filters. See "Plasma filter" for more information.