Abstract <p>Our studies confirmed that the maximum acceptable concentration (MAC) value of 0.01 mg/m³ adopted in Russia for formaldehyde in the air of residential premises is invalid. The evidence basis for this conclusion is: (1) the use of nonselective spectrophotometric methods for determining formaldehyde with the acetylacetone reagent, for which the lower limit of detectable formaldehyde content is 0.06 mg/m³ when collecting 15 dm³ of analyzed air; (2) the use of a technical aqueous solution of formaldehyde to construct a calibration graph for spectrophotometric determination of formaldehyde in air with the acetylacetone reagent; (3) non-use of the modern method of gas chromatography to determine the trace impurities of formaldehyde; (4) the result of the sanitary-chemical assessment of pine wood under simulated operating conditions in glass chambers using gas chromatography at a saturation of 2.2 m²/m³, temperature of 20°С, and gas exchange of 1 vol/h (0.15 mg/m³). It is recommended that the sanitary-chemical assessment of air and composite wood materials be performed by gas chromatography using heat-resistant porous polymer sorbents: polynaphthoylenebenzimidazoles (PNBI-1-4), polyphenylquinoxaline, or cesiumsorb to concentrate the trace impurities of volatile chemicals; formaldehyde and methanol be determined using a packed analytical column with polyphenylquinoxaline or cesiumsorb; and the flame ionization detector of the gas chromatograph be calibrated for formaldehyde by the dynamic method using Teflon ampules with methanol and a special reactor in which methanol is converted into formaldehyde without formation of organic by-products.</p>