Analysis of VOC at trace level in air

Volatile organic compounds (VOCs) include a very large number of molecules with very different physico-chemical properties. They are mainly solvents used in the chemical, pharmaceutical, cosmetics, surface treatment and printing industries, as well as plasticizers, sulfur and nitrogen compounds likely to cause odor nuisance, and aliphatic and aromatic hydrocarbons. Given this diversity, definitions have been proposed. European Directive 1999/13/EC of March 11, 1999 defines VOCs as "any organic compound having a saturation vapour pressure of 0.01 kPa or more at a temperature of 293.15 K, or having a corresponding volatility under the particular conditions of use". Under the Ministerial Order of February 2, 1998, French legislation excludes methane from this definition, as it is not very toxic and is not involved in atmospheric photochemical pollution (it is a greenhouse gas). This last criterion is also used by the US-EPA (US – Environmental Protection Agency) to define VOCs. Along with nitrogen oxides, VOCs are precursors in the formation of tropospheric ozone, which is their main impact on the environment. Health risks to humans vary according to the molecule in question. They range from olfactory discomfort to mutagenic (unsaturated hydrocarbons) and carcinogenic (aromatic hydrocarbons) effects, as well as irritation and other disorders (respiratory, cardiac, renal, headaches, etc.). Sources of VOCs can be either biotic or anthropogenic, the latter having risen steadily until the end of the 20th century, mainly as a result of industrial activity and road transport. According to CITEPA (Centre interprofessionnel d'étude sur la pollution atmosphérique), the level of non-methane VOC (NMVOC) emissions has been falling steadily since 1988, reaching 1,400 kt in 2003, a drop of 47%. During this period, a reversal of the most emitting sectors has also been observed: manufacturing industry has become predominant, accounting for 30% of total emissions in mainland France, compared with 24% for road transport, formerly the most emitting sector. These improvements are the result of the political will of many nations to reduce their emissions. Under the Gothenburg Protocol (1999), 26 European countries have committed to emission ceilings: in France, a maximum of 1,100 kt of VOCs is to be achieved by 2010.

As a result, regulations concerning industrial effluents have become stricter, and VOC emission limit values have been lowered. Similarly, ambient air quality monitoring has been organized, with limit values set for priority pollutants (including one VOC, benzene) and measurement networks set up. In comparison, regulations concerning indoor environments are still underdeveloped. Indeed, this is a relatively recent concern, even though indoor air quality has become a major public health issue. For...