Due to their numerous sources indoors, concentrations of VOCs indoors are consistently higher in
indoor air (up to ten times higher) than outdoors due to the many sources. VOCs are emitted by thousands of indoor products. Examples include: paints, varnishes, waxes and lacquers, paint strippers, cleaning and personal care products, pesticides, building materials and furnishings, office equipment such as copiers and printers,
correction fluids and
carbonless copy paper, graphics and craft materials including glues and adhesives, permanent markers, and photographic solutions. Human activities such as cooking and cleaning can also emit VOCs. Cooking can release long-chain
aldehydes and
alkanes when oil is heated and
terpenes can be released when spices are prepared and/or cooked. The total concentration of all VOCs (TVOC) indoors can be up to five times higher than that of outdoor levels. New buildings experience particularly high levels of VOC
off-gassing indoors because of the abundant new materials (building materials, fittings, surface coverings and treatments such as glues, paints and sealants) exposed to the indoor air, emitting multiple VOC gases. This off-gassing has a multi-exponential decay trend that is discernible over at least two years, with the most volatile compounds decaying with a time-constant of a few days, and the least volatile compounds decaying with a time-constant of a few years. New buildings may require intensive ventilation for the first few months, or a
bake-out treatment. Existing buildings may be replenished with new VOC sources, such as new furniture, consumer products, and redecoration of indoor surfaces, all of which lead to a continuous background emission of TVOCs, and requiring improved ventilation. Furthermore, VOC emitting products used indoors, e.g. building products and furniture, are investigated in emission test chambers under controlled climatic conditions. For quality control of these measurements round robin tests are carried out, therefore reproducibly emitting reference materials are ideally required. These methods are not limited by the adsorbing properties of materials like Tenax.
Regulation of indoor VOC emissions In most countries, a separate definition of VOCs is used with regard to
indoor air quality that comprises each organic chemical compound that can be measured as follows: adsorption from air on Tenax TA, thermal desorption, gas chromatographic separation over a 100% nonpolar column (
dimethylpolysiloxane). VOC (volatile organic compounds) are all compounds that appear in the gas chromatogram between and including
n-hexane and
n-hexadecane. Compounds appearing earlier are called VVOC (very volatile organic compounds); compounds appearing later are called SVOC (semi-volatile organic compounds).
France,
Germany (AgBB/DIBt),
Belgium,
Norway (TEK regulation) and
Italy (CAM Edilizia) have enacted regulations to limit VOC emissions from commercial products. European industry has developed numerous voluntary ecolabels and rating systems, such as
EMICODE, M1,
Blue Angel, GuT (textile floor coverings),
Nordic Swan Ecolabel,
EU Ecolabel, and
Indoor Air Comfort. In the
United States, several standards exist; California Standard CDPH Section 01350 is the most common one. These regulations and standards changed the marketplace, leading to an increasing number of low-emitting products.
Health risks Respiratory,
allergic, or
immune effects in infants or children are associated with man-made VOCs and other indoor or outdoor air pollutants. Some VOCs, such as
styrene and
limonene, can react with
nitrogen oxides or with ozone to produce new oxidation products and
secondary aerosols, which can cause sensory irritation symptoms. VOCs contribute to the formation of
tropospheric ozone and
smog. Health effects include eye, nose, and
throat irritation;
headaches, loss of coordination,
nausea, hearing disorders and
damage to the liver, kidney, and
central nervous system. Some VOCs are suspected or known to cause
cancer in humans. Key signs or symptoms associated with exposure to VOCs include conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction,
dyspnea, declines in serum
cholinesterase levels, nausea, vomiting, nose bleeding, fatigue, dizziness. The ability of organic chemicals to cause health effects varies greatly from those that are highly toxic to those with no known health effects. As with other pollutants, the extent and nature of the health effect will depend on many factors including level of exposure and length of time exposed. Eye and respiratory tract irritation, headaches, dizziness, visual disorders, and memory impairment are among the immediate symptoms that some people have experienced soon after exposure to some organics. At present, not much is known about what health effects occur from the levels of organics usually found in homes.
Ingestion While null in comparison to the concentrations found in indoor air,
benzene,
toluene, and
methyl tert-butyl ether (MTBE) were found in samples of human milk and increase the concentrations of VOCs that we are exposed to throughout the day. A study notes the difference between VOCs in alveolar breath and inspired air suggesting that VOCs are ingested, metabolized, and excreted via the extra-pulmonary pathway. VOCs are also ingested by drinking water in varying concentrations. Some VOC concentrations were over the
EPA's National Primary Drinking Water Regulations and China's National Drinking Water Standards set by the
Ministry of Ecology and Environment.
Dermal absorption The presence of VOCs in the air and in
groundwater has prompted more studies. Several studies have been performed to measure the effects of dermal absorption of specific VOCs. Dermal exposure to VOCs like
formaldehyde and toluene downregulate
antimicrobial peptides on the skin like cathelicidin LL-37, human β-defensin 2 and 3.
Xylene and formaldehyde worsen allergic inflammation in animal models. Toluene also increases the dysregulation of
filaggrin: a key protein in dermal regulation. this was confirmed by immunofluorescence to confirm protein loss and western blotting to confirm mRNA loss. These experiments were done on human skin samples. Toluene exposure also decreased the water in the trans-epidermal layer allowing for vulnerability in the skin's layers.
Limit values for VOC emissions Limit values for VOC emissions into indoor air are published by
AgBB,
AFSSET,
California Department of Public Health, and others. These regulations have prompted several companies in the paint and adhesive industries to adapt with VOC level reductions their products. VOC labels and certification programs may not properly assess all of the VOCs emitted from the product, including some chemical compounds that may be relevant for indoor air quality. Each ounce of
colorant added to tint paint may contain between 5 and 20 grams of VOCs. A dark color, however, could require 5–15 ounces of colorant, adding up to 300 or more grams of VOCs per gallon of paint.
VOCs in healthcare settings VOCs are also found in hospital and health care environments. In these settings, these chemicals are widely used for cleaning, disinfection, and hygiene of the different areas. Thus, health professionals such as nurses, doctors, sanitation staff, etc., may present with adverse health effects such as
asthma; however, further evaluation is required to determine the exact levels and determinants that influence the exposure to these compounds. Concentration levels of individual VOCs such as halogenated and aromatic hydrocarbons vary substantially between areas of the same hospital. Generally,
ethanol,
isopropanol,
ether, and
acetone are the main compounds in the interior of the site. Following the same line, in a study conducted in the United States, it was established that nursing assistants are the most exposed to compounds such as ethanol, while medical equipment preparers are most exposed to
2-propanol. In one study, more than 200 chemicals were identified, of which 41 have adverse health effects, 37 of them being VOCs. The health effects include skin sensitization, reproductive and organ-specific toxicity,
carcinogenicity,
mutagenicity, and
endocrine-disrupting properties.
VOCs in hospitality and retail Workers in hospitality are also exposed to VOCs from a variety of sources including cleaning products (air fresheners, floor cleaners, disinfectants, etc.), building materials and furnishings, as well as fragrances. One of the most common VOC found in hospitality settings are
alkanes, which are a major ingredient in cleaning products (35%). which is present in some fabrics used to make towels and bedding, however exposure decreases after several washes. Some hotels still use bleach to clean, and this bleach can form
chloroform and
carbon tetrachloride. Fragrances are often used in hotels and are composed of many different chemicals. VOCs in cleaning supplies can also cause more serious conditions, such as respiratory diseases and cancer. Additionally, due to a movement among higher-end hotels to be more environmentally friendly, there has been a shift to using less harsh cleaning agents. The concentration of VOCs present as well as the types depend on the type of store, but common sources of VOCs in retail spaces include motor vehicle exhaust, building materials, cleaning products, products, and fragrances. One study found that VOC concentrations were higher in retail storage spaces compared to the sales areas, particularly formaldehyde. In retail spaces, formaldehyde concentrations ranged from 8.0 to 19.4 μg/m3 compared to 14.2 to 45.0 μg/m3 in storage spaces. Employers can ensure proper ventilation by placing furniture in a way that enhances air circulation, as well as checking that the
HVAC (heating, ventilation, and air conditioning) system is working properly to remove pollutants from the air. Workers can make sure that air vents are not blocked. ==Analytical methods==