Trace amounts of volatile organic compounds (VOCs), such as formaldehyde, are released into the environment by the manufacture of housing materials such as furnishings, woodbased products, plastics and varnishes and also from the combustion of ethanol added to petrol to reduce carbon monoxide. Traces of formaldehyde can make people feel unwell, and prolonged exposure can cause respiratory problems, and in rare cases may induce nasal cancer.
EU regulations limit acceptable levels in buildings and the environment for VOCs, limits which are expected to be tightened. The World Meteorological Organization Global Atmosphere Watch (WMO-GAW) has implemented a worldwide VOC monitoring programme, and Europe alone has more than 50 monitoring stations, to evaluate air quality and track global trends.
To confirm air quality meets data quality objectives, monitoring instruments must be calibrated to detect trace amounts of formaldehyde at the low levels found in air. This requires stable standards – gas cylinders containing accurate amount fractions of formaldehyde – against which instruments can be calibrated.
However, formaldehyde is very reactive and sticks to the cylinders, so its amount fraction may reduce with the passage of time. As air quality regulations become stricter, new formaldehyde standards are needed which use inert materials to ensure their contents remain stable over time, in order to reliably confirm the performance of monitoring instrumentation.
The EMRP Project Metrology for VOC indicators in Air Pollution and Climate Change investigated materials which are inert to formaldehyde and used these to improve the design of systems used to generate formaldehyde gas standards, and the cylinders used for storing them.
This led to the development of a new dynamic production facility for creating very low-level formaldehyde mixtures for use as calibration standards. The inert facility creates known quantities of formaldehyde and carefully dilutes them with VOC-free gas to produce amount fractions of one part per million (ppm), which is very low for a gas reference standard. The project also investigated the stability of cylinders containing formaldehyde gas standards over time through repeated testing with highly accurate measurement instruments and confirmed that their amount fractions held and therefore these are fit for purpose.
Air Liquide, the world’s largest supplier of industrial gases, routinely supplies reference gas standards to industry and academia, including formaldehyde standards. It was one of the first to use the new project developed LNE dynamic production facility for formaldehyde gas standards to calibrate its own in-house standards.
Air Liquide anticipates increasingly stringent building regulations and outdoor air directives with tighter VOC emission requirements, which will increase the market for low level standards for confirming the performance of formaldehyde monitoring instrumentation. Air Liquide aims to be ready with a capability in place to provide these low part-per-million formaldehyde standards.
Access to more accurate standards will help polluting industries such as builders and fuel producers, as well as governments and local authorities, to monitor, control and reduce formaldehyde emissions and to demonstrate compliance with increasingly strict regulations.