Implications for Good Building Practices

Basic options for controlling indoor VOCs

While there are many uncertainties about the health risks of indoor VOCs and SVOCs, the evidence of health risks is clearly sufficient to justify taking precautionary measures to limit VOC and SVOC exposures, including reducing indoor sources, reducing entry indoors from outdoors, and reducing indoor concentrations through either increased outdoor air ventilation of air cleaning technologies.  These options are discussed in more detail below

Eliminating or limiting the indoor sources of VOCs and SVOCs is the first option to consider. Some specific furnishing items have been shown to be significant sources of VOC exposures; for instance, crib mattresses can cause important increases in the levels and diversity of VOC exposures for infants, due to infant proximity to and warming of the mattresses [1]. In some cases, sources can be easily eliminated or reduced through behavior changes or product substitutions. Examples of such measures include avoiding smoking indoors, not using moth crystals or air fresheners, not using perfumes, and employing integrated pest management practices to reduce or eliminate pesticide applications. Paints, solvents, and cleaning products can be carefully sealed and stored outside of the occupied space, e.g., in a well-ventilated exterior closet, shed, or detached garage. Storage of such source materials or fuels such as gasoline or kerosene in attached garages is not generally advisable, as emissions can contaminate indoor air in homes. Information available on specific subpopulations, housing characteristics, and activities associated with higher exposures to specific indoor pollutants may help identify specific changes that effectively reduce these exposures [2]. With sufficient knowledge and tenacity, builders, building owners, and building maintenance staff can select building materials, furnishings, and cleaning products that emit VOCs at a lower rate. For example, low VOC products such as paints and caulks are becoming more widely available.

Solid wood, or low-formaldehyde-emission products will emit much less formaldehyde than products made of conventional particle board or medium-density fiber board, although cost may be higher. This may be of special concern for infant furnishings (e.g., [3]). California Title 17 Air Toxics Control Measures regulations require reduced formaldehyde emissions from composite wood products and finished goods that contain composite wood products sold, offered for sale, supplied, used or manufactured for sale in California [4], and Title VI of the Toxic Substances Control Act (TSCA) sets national formaldehyde emission standards for composite wood products that are identical to California’s Phase II emission standards. As of 2014, EPA was developing the regulations to implement these standards nationally [5].

Overall, however, indoor source control for VOCs is challenging. The number of materials and products used in buildings that emit VOCs is large, data on the VOC emission rates are often very limited, and products change over time. Product substitution – for example vinyl flooring in place of carpet – may reduce the sources of some types of VOCs while increasing the sources of other VOCs. Substituting products with lower VOC emission rates may be more expensive than using standard products. There are some labeling and certification programs designed to make it easier to select low-VOC products. Additional sources of information on reducing indoor VOC sources are provided below.

Reducing the entry of outdoor-produced VOCs into the indoor environment is also important. Ventilation system air intakes and openable windows should be kept separated from outdoor emission sources, such as busy roads, parking areas, and loading docks.

Outdoor air ventilation is a main option for reducing existing indoor VOC concentrations. When more outdoor air is provided, either through a mechanical ventilation system containing fans, or by increased opening of doors and windows, the indoor air concentrations of VOCs released from indoor sources will decrease. While increased ventilation is often considered easier to apply than VOC source control, and ventilation simultaneously reduces concentrations of many VOCs, ventilation increases energy use and will often result in smaller reductions in indoor VOC concentrations than can be achieved with VOC source control. Also, when more outdoor air is provided, indoor air concentrations of outdoor air pollutants can increase, and these pollutants often pose health risks. Furthermore, the increased energy use from increased mechanical ventilation contributes to the emission of carbon dioxide to the outdoor atmosphere, which is a source of climate change. For more information on the health consequences of ventilation and guidance on best practices for ventilation, see the section of this website on ventilation (provide link). It is important to note that increased ventilation will not be highly effective in reducing airborne concentrations of higher molecular weight SVOCs that are present mostly on indoor surfaces [6]. For these SVOCs, as one increases the amount of ventilation to remove airborne SVOCs, the emission rates of SVOCs from surfaces increases, counteracting the desired effects of the increased ventilation.

Use of an air cleaning system designed to remove VOCs from the indoor air is another option for reducing existing indoor VOC concentrations. While many air purifiers designed to remove both particles and VOCs from indoor air are available on the market, data on the long term effectiveness of these systems in reducing indoor VOC levels is very limited. Until more data become available, VOC source control and ventilation will usually be the preferred options. Because air cleaning technologies are changing rapidly, new technologies could eventually make VOC air cleaning a more attractive option.

Links to Additional Information

The following text provides links to additional practical information on practices for reducing indoor VOC levels and provides links to related web sites. The following are examples of links to information from U.S. sources. A large number of web sites and information sources exist from around the world.