Air fresheners are consumer products that mitigate unpleasant odors in indoor spaces. They work in one of five ways:

Absorption: Adsorbents like activated charcoal or silica gel may be used to absorb offending, chemical odors.
Chemical neutralization: Substances such as rubber may be used for some odors.
Disinfection. Odors caused by bacterial activity can be eliminated by disinfectants like ozone or bleaching agents containing hydrogen peroxide, chlorine or hypochlorites.
Masking: Many "fresheners" obscure odors with a fragrance.
Anesthetization: Some air fresheners use anesthetics to dull the sense of smell.

AIR fresheners and aerosols may make homes unhealthier, research has suggested. Children and their mothers suffered more ill health in homes where these products were in daily use, the University of Bristol’s Children of the 90s study has shown.

The study, to be published this week in Archives of Environmental Health, shows that children suffered diarrhoea and earache, while their mothers had more headaches and depression, according to a study of 14,000 households.

As 40 per cent of households use the products found to be responsible, the results have wide implications if confirmed.

The team says that the VOC(volatile organic compounds) levels in the homes were linked with the use of three products: aerosols, air fresheners and carpet cleaner. They then compared the use of those three products in the whole sample with the incidence of illness.The team used measurements of VOCs, taken month by month, in the bedrooms and living rooms of 170 households. VOCs have been linked with a number of illnesses.

They found that 32 per cent more babies suffered diarrhoea in homes where air fresheners (including sticks, sprays and aerosols) were used every day, compared with homes where they were used once a week or less. They also suffered significantly more from earache. Air fresheners and aerosols also affected mothers, with those who used them daily suffering nearly 10 per cent more headaches. The most surprising result is the apparent link between maternal depression and air fresheners. Of mothers who used fresheners, 16 per cent reported depression, against 12.7 per cent of those who seldom used them. Dr Farrow said: “Over 40 per cent of families in the study reported using air fresheners regularly. People may think using these products makes their homes cleaner and healthier, but being cleaner may not necessarily mean healthier.

“Air fresheners combined with other aerosol and household products contribute to a complex mixture of chemicals and a build-up of VOCs in the home environment. Pregnant women and babies up to six months may be particularly susceptible to the effects, because they spend around 80 per cent of their time at home. There may also be implications for other groups who are at home a good deal, such as old people.

New research shows that a chemical compound found in many air fresheners, toilet bowl cleaners, mothballs and other deodorizing products, may be harmful to the lungs. Human population studies at the National Institute of Environmental Health Sciences (NIEHS), a part of the National Institutes of Health, found that exposure to a volatile organic compound (VOC), called 1,4 dichlorobenzene (1,4 DCB) may cause modest reductions in lung function.

“Even a small reduction in lung function may indicate some harm to the lungs,” said NIEHS researcher Stephanie London, M.D., lead investigator on the study. “The best way to protect yourself, especially children who may have asthma or other respiratory illnesses, is to reduce the use of products and materials that contain these compounds.”

The researchers examined the relationship between blood concentrations of 11 common volatile organic compounds and lung function measures in a representative sample of 953 adults. VOCs are a diverse set of compounds emitted as gases from thousands of commonly used products, including tobacco smoke, pesticides, paints, and cleaning products. VOCs are also released through automotive exhaust. The researchers found that of the common VOCs analyzed, which included benzene, styrene, toluene, and acetone, only the compound 1,4 DCB was associated with reduced pulmonary function and this effect was seen even after careful adjustment for smoking, The researchers found that 96 percent of the population samples had detectable 1,4 DCB blood concentration levels. African Americans had the highest exposure levels and non-Hispanic whites the lowest.

This particular VOC, 1,4 DCB, is a white solid compound with a distinctive aroma, similar to mothballs. It is typically used primarily as a space deodorant in products such as room deodorizers, urinal and toilet bowl blocks, and as an insecticide fumigant for moth control.

“Because people spend so much time indoors where these products are used, it’s important that we understand the effects that even low levels might have on the respiratory system,” said Leslie Elliott, Ph.D. a researcher on the NIEHS-funded study. “There has been very little research on the health effects of this particular compound in non-occupational settings.”

The researchers used data from the third National Health and Nutrition Examination Survey (NHANES) and a special component of the study specifically designed to assess the level of common pesticides and VOCs in the US population. NHANES III is a nationally representative survey conducted by the Centers for Disease Control and Prevention between 1988-1994 to determine the health and nutritional status of the U.S. population.

Data from 953 adults 20-59 years old who had both VOC blood measures and pulmonary function measures are included in the study published in the August issue of Environmental Health Perspectives. Four pulmonary function measures were used in the analyses. The researchers found modest reductions in pulmonary function with increasing blood concentrations of 1,4 DCB.

There was approximately a 4 percent decrease in the test which measures forced expiratory volume in 1(FEV1) second between the highest and lowest levels of exposure. FEV1 is a commonly used index for assessing airway function and obstruction.

The researchers assessed the influence of other factors in an individual’s environment that may be related to pulmonary function and to 1,4-DCB exposure, such as type of heating, use of wood fires, age of house, presence of furred pets, occupation, socioeconomic status, environmental tobacco smoke, smoking history, and diagnosis of asthma or emphysema. The authors noted that participants might have been exposed to other agents not assessed in this study1that have been linked to both respiratory impairment and levels of 1,4-DCB.

“This research suggests that 1,4-DCB may exacerbate respiratory diseases,” said David A. Schwartz, M.D., NIEHS Director. “As part of the new disease-focused approach at NIEHS, researchers will use this information to better understand the pathogenesis of respiratory diseases.”

“Aerosol forms of these products are labelled with advice that they should not be used in confined spaces and current evidence shows these products are safe. We shall be looking into the new research to see whether people are following advice and whether additional advice may be required."