Asthma and chemical sensitivity

1: Prevalence of fragrance sensitivity in the American population
Caress SM, Steinemann AC.
J Environ Health. 2009 Mar;71(7):46-50.
pmid 19326669

This study determined the percentages of individuals who report adverse
effects from exposure to fragranced products in the U.S. population and
in subpopulations of those with asthma or chemical sensitivity. Data
were collected through telephone interviews from two geographically
weighted, random samples of the continental U.S. in two surveys during
2002-2003 and 2005-2006 (1,057 and 1,058 cases, respectively).
Respondents were asked if they find being next to someone wearing a
scented product irritating or appealing; if they have headaches,
breathing difficulties, or other problems when exposed to air fresheners
or deodorizers; and if they are irritated by the scent from laundry
products, fabric softeners, or dryer sheets that are vented outside.
Results aggregated from both surveys found that 30.5% of the general
population reported scented products on others irritating, 19% reported
adverse health effects from air fresheners, and 10.9% reported
irritation by scented laundry products vented outside. This study
reveals that a considerable percentage of the U.S. population reports
adverse health effects or irritation from fragranced products, with
higher percentages among those with asthma and chemical sensitivity.

2: Asthma and chemical hypersensitivity: prevalence, etiology, and age
of onset
Caress SM, Steinemann AC.
Toxicol Ind Health. 2009 Feb;25(1):71-8.
http://tih.sagepub.com/cgi/reprint/25/1/71

This study investigates asthma's national prevalence and potential
overlap with chemical hypersensitivity. It also examines asthma's
etiology, age of onset, and demographic characteristics. Data were
collected from a geographically weighted random sample of the
continental U.S. (1058 cases), in four seasonal cohorts (2005-2006). The
study found that 12.9% of the sample report asthma, 11.6% report
chemical hypersensitivity, and 31.4% of those with asthma report
chemical hypersensitivity. Among asthmatics, 38% report irritation from
scented products, 37.2% report health problems from air fresheners, and
13.6% report their asthma was caused by toxic exposure. Asthma cases
affected each racial/ethic group in roughly the same proportion, with
nearly 50% classified as childhood onset.