Aircare is a pretty sizeable market these days - worth well over £300m, according to Nielsen - and, because it's a luxury rather than a necessity, there is plenty of potential for growth. Producers are going all-out to develop new and ever-more sophisticated products.

"The innovation in the category reflects consumers' desires to enhance their home environment rather than simply mask bad smells," says Phil Thomas, marketing director of Reckitt Benckiser, household and personal care. "The growth potential for the category continues to be high."

The three leading brands are Reckitt Benckiser's Air Wick, SC Johnson's Glade, and Ambi Pur, which is owned by Sara Lee. Each had a major marketing budget behind it last year, with third-placed Ambi Pur showing the best return, rising by more than 30%. Air Wick, which is still more than twice the size of Ambi Pur, added 13.2% to its value, while Glade slipped back a little. Oust - last year's early star - has failed to capitalise on its impressive start, with sales sliding 6.6% as rivals woke up to the popularity of odour eliminators.

Automatic spray products and those that alternate fragrances to combat 'olfactory fatigue' - when the nose becomes inured to one scent and can no longer smell it - are proliferating, says Thomas.

P&G has added a spray product to its Febreze fabric and aircare brand in the form of Mist & Refresh nitrogen-based aerosol, which contains a patented Cyclodextrin odour elimination technology. It has also brought out a Plug & Refresh product that continuously eliminates everyday odours and automatically alternates between two complementary scents for freshness.

Air Wick is also set to add an alternating fragrance combination line called Symphonia to its line-up early this year. The company will promote this with TV advertising as part of the brand's sponsorship of ITV soap Emmerdale as well as in-store promotions. Reckitt Benckiser is also introducing a new fragrance across all air freshener formats for spring 2008 - Refreshing Green Apple and Water Lily.

CFCs may have been tackled, but aircare was never going to escape further analysis under the green microscope. Eco-friendly pioneer Ecover is leading the march, having introduced a new range of room fragrances based on plant extracts and essential oils. "Most conventional products use non-renewable ingredients and synthetic perfumes, and customers want an ecological alternative," says marketing manager Clare Allman.

"Ecover has pioneered products that provide people with an effective ecological alternative and we see room fragrance as a natural extension."n