Expert reviews for Envion's Therapure line of air purifiers state that they offer great value and provide a high level of functionality for users, as of March 2015. Many reviews focsus on the Envion Therapure's beneficial effects for people with respiratory illnesses.
The Frugal Hotspot site contains many reviews for budget-conscious shoppers seeking high quality home products, including air purifiers. Its review of the Envion Therapure TPP540 series covers many of its useful functions and features, including the unique way it offers extensive air purification. In addition to a standard filtration process that involves a fan drawing air into the machine, passing it through a filter to collect allergens and pollutants, then passing it back into the room, the TPP540 uses a UV light to eliminate airborne contaminants. This light projects onto all the air passing through the system, killing any germs present in the air.
The site also notes the versatility of the model, including its three fan speed settings, which allow for varying degrees of filtration depending on the situation. The reviewer gave the model high praise for being able to quickly eliminate unwanted odors within a room, which is a commonly desired feature that not all purifying air filters possess.