emissions. Secondary formation of formaldehyde occurs in the atmosphere through the photochemical oxidation of natural and anthropogenic volatile organic compounds (VOCs) in the air.

Formaldehyde is used predominantly in the synthesis of resins, with urea-formaldehyde resins, phenolic-formaldehyde resins, pentaerythritol, and other resins accounting for the major use of Canadian consumption. They are used to manufacture building materials and numerous household products such as plastics, adhesives, paints, varnishes, dyes and fertilizers etc... Because formaldehyde is also a product of combustion, fuel-burning devices like woodstoves, fireplaces, gas stove or kerosene space heaters can also be potential sources.

Some common indoor sources of formaldehyde:

Ozone can also cause the formation of formaldehyde through chemical reaction with some building materials such as plaster, plywood and carpet etc.  Office equipments (photocopiers and laser printers) have been found to release formaldehyde possibly through oxidation reaction of ozone with aliphatic hydrocarbons from these equipments.

Exposure Guidelines
Residential indoor air quality guidelines for formaldehyde (Health Canada 2006).

Average exposure concentrations to formaldehyde and contribution of various atmospheric environments to average exposure to formaldehyde.

Analytical Methods for Formaldehyde
A number of analytical methods have been employed to determine the airborne concentration of formaldehyde.  Active and passive sampling techniques have been used, both have their advantages in different applications.  For example, passive samplers are useful in the absence of the sampling pumps, or in situations where longer time sampling is required.  They are also small, light and easy to wear or deploy which is important for personal exposure and indoor measurement.  The most sensitive method is through the use of high performance liquid chromatography, which has detection limits of low parts per billion (ppb) levels.  The methods for the determination of formaldehyde in air are shown in the following table:

CASSEN’s Analytical Performance
In addition to sensitivity, CASSEN demonstrates excellent data quality through participation in the only international proficiency program for formaldehyde offered by the United Kingdom Health and Safety Laboratory (HSL), a laboratory of UK’s Health and Safety Executive (HSE) - Workplace Analysis Scheme for Proficiency (WASP) Program. The program provides independent verification of the analytical competence and accuracy of a laboratory giving analysts confidence that the services which they provide will withstand scrutiny. A recent round of formaldehyde proficiency results is shown here and indicates the consistent accuracy and excellent data quality of CASSEN’s performance.

References