An article in the March 2009 edition of the Journal of Environmental Health summarizes the results of a study done over several years' time concerning the number of people adversely affected by the chemicals in fragrances. Authors Stanley M. Caress and Anne C. Steinemann (an environmental engineer at the University of Washington) concluded that 30.5% of the general population report scented products on others to be irritating. That's nearly one in three people. So much for those claims by the fragrance producers that we will be more attractive to others if we use their products.
Anne C. Steinemann is the same scientist who conducted extensive research into the chemicals found in air fresheners and their effect on people who use them (see "Fragranced consumer products and undisclosed ingredients" in the January 2009 issue of Environmental Impact Assessment Review, pp 32-38). In that research she found that the largest contributors of VOCs to human exposure come from sources closest to us, particularly consumer products, most of which are unregulated and untested for human safety.
In their combined research, Caress and Steinemann found that 19% of people have adverse health effects from air fresheners, and 10.9% of people report irritation from scented laundry products which vent outside in residential areas. Symptoms reported include headaches, breathing difficulties and neurological ailments. These percentages reflect the general population. Among people with diagnosed asthma and/or chemical sensitivity, the percentages are much higher for "adverse health effects or irritation from fragranced products."
None of this comes as any surprise to those of us who struggle with chemical sensitivity, but it's nice to have some scientific research to back up what many consider only anecdotal evidence.