Contrast-enhanced dynamic and static MRI correlates with quantitative 99Tcm-labelled nanocolloid scintigraphy. Study of early rheumatoid arthritis patients.

OBJECTIVE: The aim of this study was to evaluate the roles of contrast-enhanced dynamic and static magnetic resonance imaging (MRI) and quantitative 99Tcm-labelled nanocolloid (NC) scintigraphy in detecting wrist joint inflammation in early rheumatoid arthritis (RA) patients. METHODS: Twenty-eight early RA patients (median symptom duration 5 months, range 1-12 months) underwent MRI, NC scintigraphy, laboratory and clinical examinations. Static wrist MRI scans were retrospectively scored for synovitis, bone oedema and erosions by two independent readers using the recently published rheumatoid arthritis MRI scoring system (RAMRIS). Twenty NC scans were analysed quantitatively by measuring maximum 99Tcm-NC uptake in three small areas of each wrist. From the same locations on the wrists, dynamic MRI gadolinium-diethylenetriaminepenta-acetic acid (Gd-DTPA) enhancement rates (E-rate) were measured. The average 99Tcm-NC uptake of the whole wrist region was also measured and average E-rates were calculated. Correlations between MRI and NC scintigraphy measurements were calculated. Correlations between imaging methods of the wrist and the global measures of inflammation (laboratory and clinical examinations) were also assessed. RESULTS: Strong correlations emerged between maximal 99Tcm-NC uptake and MRI E-rates, reflecting similar performance of the methods in detecting local synovial inflammation. 99Tcm-NC uptake and MRI E-rate correlated with semiquantitative scoring of synovitis and bone oedema from static MRI scans. The erythrocyte sedimentation rate (ESR) correlated with MRI scores, E-rate and 99Tcm-NC uptake. No correlation between the clinical parameters and the imaging methods was detected. Inter-observer reliability for scoring synovial hypertrophy, bone oedema and bone erosions from static MR images were high (single-measure fixed-effects intra-class correlations 0.87, 0.93 and 0.91 respectively). Intra-observer reliability for E-rate and 99Tcm-NC measurements of 10 randomly picked scans was found to be high, with an intra-class correlation of 0.92; 95% confidence interval (CI) 0.84-0.96 and 0.99; 95% CI 0.98-1.00, respectively. CONCLUSIONS: Objective information about wrist joint inflammation can be obtained with contrast-enhanced dynamic MRI and quantitative 99Tcm-labelled NC scintigraphy. MRI also allows visualization and semiquantitative scoring of bone oedema and erosions of the wrist. Dynamic MRI and NC scintigraphy are safe and easy to perform, and they can be used in a long-term follow-up of rheumatoid patients.

Ultrasonography of salivary glands in primary Sjogren's syndrome. A comparison with magnetic resonance imaging and magnetic resonance sialography of parotid glands.

OBJECTIVES: To evaluate ultrasonography (US) of salivary glands in primary Sjögren's syndrome (SS) and to compare US with parotid magnetic resonance (MR) imaging and MR sialography. METHODS: US examination of parotid, submandibular and sublingual glands was performed on 27 patients with primary SS, 27 healthy controls and 27 symptomatic controls without SS. The results were compared with parotid MR imaging and MR sialography and the clinical features of the patients. RESULTS: Salivary gland abnormalities, parenchymal inhomogeneity or adipose degeneration, were visualized in 21 (78%) SS patients, in one healthy control and in two symptomatic controls by US. Eighteen (67%) patients had changes in the parotid and submandibular glands and 8 (30%) changes in the sublingual glands. In the comparison, MR sialography was found to be the most sensitive method (96%), followed by MR imaging (81%) and US (78%), in detecting glandular changes. The specificity of US was 94%. The US and MR results were related to anti-Ro/SSA positivity but not to saliva secretion. The focus scores were related only to parotid MR imaging findings. CONCLUSIONS: US, MR imaging and MR sialography with modern technology have reached such a good accuracy in visualizing glandular structural changes that they are promising alternatives to the conventional invasive examinations in the diagnostics of SS.

Stratification of welding fumes and grinding particles in a large factory hall equipped with displacement ventilation.

The purpose of the study was to investigate the performance of displacement ventilation in a large factory hall where large components of stainless steel for paper, pulp and chemical industries were manufactured. The performance of displacement ventilation was evaluated in terms of concentration distributions of welding fumes and grinding particles, flow field of the supply air and temperature distributions. Large differences in vertical stratification patterns between hexavalent chromium (Cr(VI)) and other particulate contaminants were observed. The concentration of Cr(VI) was notably lower in the zone of occupancy than in the upper part of the factory hall, whereas the concentrations of total airborne particles and trivalent chromium (Cr(III)) were higher in the occupied zone than in the upper zone. The stratification of Cr(VI) had the same tendency as the air temperature stratification caused by the displacement flow field.

Human alpha3-fucosyltransferases convert chitin oligosaccharides to products containing a GlcNAcbeta1-4(Fucalpha1-3)GlcNAcbeta1-4R determinant at the nonreducing terminus.

Human alpha3-fucosyltransferases (Fuc-Ts) are known to convert N-acetyllactosamine to Galbeta1-4(Fucalpha1-3)GlcNAc (Lewis x antigen); some of them transfer fucose also to GalNAcbeta1-4GlcNAc, generating GalNAcbeta1-4(Fucalpha1-3)GlcNAc determinants. Here, we report that recombinant forms of Fuc-TV and Fuc-TVI as well as Fuc-Ts of human milk converted chitin oligosaccharides of 2-4 GlcNAc units efficiently to products containing a GlcNAcbeta1-4(Fucalpha1-3)GlcNAcbeta1-4R determinant at the nonreducing terminus. The product structures were identified by mass spectrometry and nuclear magnetic resonance experiments; rotating frame nuclear Overhauser spectroscopy data suggested that the fucose and the distal N-acetylglucosamine are stacked in the same way as the fucose and the distal galactose of the Lewis x determinant. The products closely resembled a nodulation factor of Mesorhizobium loti but were distinct from nodulation signals generated by NodZ-enzyme.

Tetrachloroethylene emissions and exposure in dry cleaning.

Tetrachloroethylene (PCE) emissions and the exposure of workers in six commercial and three industrial dry-cleaning establishments that use dry-to-dry machines were determined. The personal samples and area samples [8-hr time-weighted average (TWA) and short-term exposure] were collected with charcoal tubes and passive monitors. The temporal variation of PCE concentration in the workplace air was monitored using a Fourier transform infrared analyzer (FTIR). The PCE emission rates were determined by multiplying the average PCE concentration in the room and the total airflow rate in the room. The PCE emissions were related to the cleaning rate in units of kg/hr. The operators' mean TWA exposure in commercial shops and industrial establishments was 28 (4.1 ppm) and 32 mg/m3 (4.6 ppm), and the pressers' exposure was 3.4 (0.5 ppm) and 7.7 mg/m3 (1.1 ppm), respectively. The customer service personnel had the lowest TWA exposure with a mean value of 0.8 mg/m3 (0.1 ppm). The highest peak concentration (2300 mg/m3; 334 ppm) was observed during cleaning of the lint and button trap, during which operation respirators were used. The PCE emission rates ranged from 4 to 118 g/hr corresponding to emission factors (mass of solvent evaporated per mass of cleaned cloths) of 0.3-3.6 g/kg. The workers' exposure to PCE was below the occupational limit values in the United States [according to the American Conference of Governmental Industrial Hygienists (ACGIH)] and in Finland. The outdoor PCE emissions were clearly below the limit values given in the European Union volatile organic compound (VOC) directive requirements.

Magnetic resonance imaging and magnetic resonance sialography of parotid glands in primary Sjogren's syndrome.

OBJECTIVE: To look for structural parotid gland changes on magnetic resonance (MR) imaging and MR sialography of primary Sjögren's syndrome (SS) patients and healthy control subjects and to compare these methods with each other. METHODS: MR imaging and MR sialography of both parotid glands were performed on 26 patients and 7 healthy controls. Bilateral surface coils were used to obtain high spatial resolution. RESULTS: Twenty-two of the 26 patients had abnormalities on MR imaging. Twenty-one had a nodular or dendritic parenchymal pattern, 5 had cavities, and 6 had duct dilatations. On MR sialography, 25 of the 26 patients had abnormalities of the ducts, and 16 of them also had cavities. One patient and all 7 controls had normal results with both methods. The structural appearance of the parotid glands on MR images had marginal linear association with the duct system changes but no correlation with the cavitary changes seen on MR sialography. Furthermore, duct system abnormalities did not correlate with cavitary changes. Both parenchymal and sialographic abnormalities were associated with the presence of Ro/SSA antibodies but not with age of the patient, disease duration, salivary flow rate, or the presence of hypergammaglobulinemia or extraglandular manifestations. CONCLUSION: MR imaging and MR sialography are noninvasive methods that provide definitive information of morphologic changes in parotid glands and can be used as diagnostic indicators of primary SS. Because these methods give information on different aspects of glandular pathology, both should be performed when evaluating parotid glands of SS patients. MR sialography is more sensitive, but conventional MR imaging gives complementary information on the progressive pathologic changes of glandular parenchyma.

No signs of autonomic nervous system dysfunction in primary Sjörgen's syndrome evaluated by 24 hour heart rate variability.

OBJECTIVE: Autonomic neuropathy is associated with increased mortality. In patients with primary Sjögren's syndrome (SS), disturbances in the autonomic nervous system have been described using conventional cardiovascular reflex tests. Heart rate variability (HRV) measured from Holter recording has proved to be a reliable and sensitive method in assessing autonomic function and prognosis. We evaluated cardiovascular autonomic function based on HRV in patients with primary SS compared to the general population. METHODS: We analyzed HRV from 24 h electrocardiography recordings in 28 patients with primary SS and 28 healthy age and sex-matched population-based controls. RESULTS: There were no significant differences in time or frequency domains or nonlinear measures of HRV between the groups. CONCLUSION: The prevalence of autonomic disturbances is not increased in patients with primary SS compared to the general population.

The acceptor and site specificity of alpha 3-fucosyltransferase V. High reactivity of the proximal and low of the distal galbeta 1-4GlcNAc unit in i-type polylactosamines.

We report here on in vitro acceptor and site specificity of recombinant alpha3-fucosyltransferase V (Fuc-TV) with 40 oligosaccharide acceptors. Galbeta1-4GlcNAc (LN) and GalNAcbeta1-4GlcNAc (LDN) reacted rapidly; Galbeta1-3GlcNAc (LNB) reacted moderately, and GlcNAcbeta1-4GlcNAc (N, N'-diacetyl-chitobiose) reacted slowly yet distinctly. In neutral and terminally alpha3-sialylated polylactosamines of i-type, the reducing end LN unit reacted rapidly and the distal (sialyl)LN group very slowly; the midchain LNs revealed intermediate reactivities. The data suggest that a distal LN neighbor enhances but a proximal LN neighbor reduces the reactivity of the midchain LNs. This implies that Fuc-TV may bind preferably the tetrasaccharide sequence Galbeta1-4GlcNAcbeta1-3Galbeta1-4GlcNAc for transfer at the underlined monosaccharide. Terminal alpha3-sialylation of i-type polylactosamines almost doubled the reactivities of the LN units at all positions of the chains. We conclude that, in comparison with human Fuc-TIV and Fuc-TIX, Fuc-TV reacted with a highly distinct site specificity with i-type polylactosamines. The Fuc-TV reactivity of free LNB resembled that of LNBbeta1-3'R of a polylactosamine, contrasting strongly with the dissimilarity of the reactivities of the analogous pair of LN and LNbeta1-3'R. This observation supports the notion that LN and LNB may be functionally bound at distinct sites on Fuc-TV surface. Our data show that Fuc-TV worked well with a very wide range of LN-glycans, showing weak reactivity only with distal (sialyl)LN units of i-type polylactosamines, biantennary N-glycans, and I branches of polylactosamines.

Emission of ozone and organic volatiles from a selection of laser printers and photocopiers.

To estimate the impact of office equipment on the quality of indoor air, the emission of ozone and organic volatiles was measured from one photocopier and four laser printers, three of which operated according to traditional corona discharge technology. The laser printers equipped with traditional technology emitted significant amounts of ozone and formaldehyde. Lesser amounts of other volatile aldehydes were emitted during printing. The photocopier emitted mainly ozone. In a well-ventilated office environment, the amounts encountered here for individual volatiles were within recommended maximum exposure limits for a reasonable density of printers. Because it is not known whether the concentration of irritating volatiles, such as formaldehyde, should be kept lower in an ozone rich environment or not, and because emissions in the immediate vicinity of the printers exceeded recommendations, the authors recommend that laser printers equipped with the traditional corona rods not be placed beside or immediately at the working site of office personnel. This way, ozone concentrations can be kept below recommended maximum exposure limits, provided that the ventilation rate is adequate. Further, it seems that if a reliable quantitative comparison of total organic volatiles prior to and during printing is to be made, the inertness of the sorbent toward ozone should be confirmed.

Contaminant dispersion in the vicinity of a worker in a uniform velocity field.

The transportation of gaseous contaminant from a low and moderate low impulse (momentum<1 m s(-1)) source to the breathing zone was studied in a uniform air stream flow. Results of the effects of the direction and the velocity of principal air flow, convection due to a human body, arm movement of a human being and the type of source on the concentration profiles are presented. Three important results were obtained. Firstly, for a given low and moderate impulse low impulse contaminant source in the near field of a worker, his/her orientation relative to the principal air flow direction is the most important factor in reducing occupational exposure, with an air velocity of about 0.3 m s(-1). Secondly, the effect of convection resulting from body heat on air flow was lower than expected. Thirdly, arm movements influence contaminant dispersion, and should be included when models assessing exposure are developed. The present data can also be used to validate existing computational fluid dynamic (CFD) models.

Primary Sjögren's syndrome with severe central nervous system disease.

OBJECTIVE: Central nervous system (CNS) involvement in primary Sjögren's syndrome (pSS) is controversial with regard to frequency, significance, and etiology. METHODS: We describe a young woman with pSS and severe CNS disease and review the literature on the pathophysiology, clinical significance, symptoms, diagnostic examinations, and treatment of CNS disease with concomitant pSS (CNS-SS). RESULTS: Our patient with pSS had a 5-month history of benign lymphadenopathy and myositis, after which she developed severe CNS disease, vasculitic lesions on her hands, and a neurogenic bladder attributable to spinal cord involvement. The diagnosis was based on the clinical picture and the results of a brain magnetic resonance imaging (MRI) scan, electroencephalography (EEG), and cerebrospinal fluid (CSF) analysis. The disease did not respond to corticosteroids, but the administration of cyclophosphamide resulted in recovery. In the literature, the incidence of CNS-SS varies widely, from rare to incidence rates of 20% to 25%. The clinical picture is diverse, ranging from mild cognitive symptoms to fatal cerebrovascular accidents. The pathophysiology of CNS-SS is unclear, specific diagnostic methods are not available, and diagnosis is based on the clinical picture and a combination of examinations. MRI is the most sensitive test and cerebral angiography the most specific. CSF reflects involvement of the leptomeninges, and EEG is nonspecific. There are no controlled studies of the treatment of CNS-SS. Regimens for vasculitis are commonly used. CONCLUSIONS: CNS-SS is uncommonly recognized and difficult to diagnose. Increasingly accurate and available diagnostic examinations will yield more information about the association of CNS disease with pSS.

Biosynthesis of sialylated and fucosylated selectin ligands of HL-60 cells in vitro. Midchain alpha3-fucose units inhibit terminal alpha6-sialylation but not alpha3-sialylation of polylactosamines.

Polylactosamines Neu5Ac alpha2-3'Lex beta1-3'Lex beta1-3'Lex and Neu5Ac alpha2-3'LNbeta1-3'Lex beta1-3'Lex [Lex, Gal beta1-4(Fuc alpha1-3)GlcNAc; LN, Gal beta1-4GlcNAc] decorate selectin counterreceptors in human HL-60 cells. Here, we show that HL-60 cell lysates catalyze distal alpha3-sialylation of LNbeta1-3'LNbeta1-3'LN and LNbeta1-3'Lex beta1-3'Lex efficiently, outlining two potential sets of biosynthetic pathways leading to the selectin ligands. In one set, alpha3-sialylation precedes internal fucosylation of the polylactosamine backbone, whereas in the other one, internal fucosylation is initiated before alpha3-sialylation. In contrast to alpha3-sialylation, LNbeta1-3'Lex beta1-3'Lex was alpha6-sialylated much less efficiently than LNbeta1-3'LNbeta1-3'LN by HL-60 cell lysates. Hence, internal fucosylation may regulate the extent of alpha6-sialylation of polylactosamines in these cells.

Isolation and characterization of linear polylactosamines containing one and two site-specifically positioned Lewis x determinants: WGA agarose chromatography in fractionation of mixtures generated by random, partial enzymatic alpha3-fucosylation of pure polylactosamines.

We report that isomeric monofucosylhexasaccharides, Galbeta1-4GlcNAcbeta1-3Galbeta1-4GlcNAcbeta1- 3Galbeta1-4(Fucalpha1-3) GlcNAc, Galbeta1-4GlcNAcbeta1-3Galbeta1-4(Fucalpha1-3) GlcNAcbeta1-3Galbeta1-4 GlcNAc and Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-3Galbeta1- 4GlcNAcbeta1-3Galbeta1-4 GlcNAc, and bifucosylhexasaccharides Galbeta1-4GlcNAcbeta1-3Galbeta1-4(Fucalpha1-3) GlcNAcbeta1-3Galbeta1-4(Fucalpha1-3)GlcNAc, Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-3Galbeta1- 4GlcNAcbeta1-3Galbeta1-4 (Fucalpha1-3)GlcNAc and Galbeta1-4(Fucalpha1-3)GlcNAcbeta1-3Galbeta1-4( Fucalpha1-3)GlcNAcbeta1-3Galbeta1-4GlcNAc can be isolated in pure form from reaction mixtures of the linear hexasaccharide Galbeta1-4GlcNAcbeta1-3Galbeta1-4GlcNAcbeta1- 3Galbeta1-4GlcNAc with GDP-fucose and alpha1,3-fucosyltransferases of human milk. The pure isomers were characterized in several ways;1H-NMR spectroscopy, for instance, revealed distinct resonances associated with the Lewis x group [Galbeta1-4(Fucalpha1-3)GlcNAc] located at the proximal, middle, and distal positions of the polylactosamine chain. Chromatography on immobilized wheat germ agglutinin was crucial in the separation process used; the isomers carrying the fucose at the reducing end GlcNAc possessed particularly low affinities for the lectin. Isomeric monofucosyl derivatives of the pentasaccharides GlcNAcbeta1-3Galbeta1-4GlcNAcbeta1-3Galbeta1- 4Gl cNAc and Galalpha1-3Galbeta1-4GlcNAcbeta1-3Galbeta1-4G lcN Ac and the tetrasaccharide Galbeta1-4GlcNAcbeta1-3Galbeta1-4GlcNAc were also obtained in pure form, implying that the methods used are widely applicable. The isomeric Lewis x glycans proved to be recognized in highly variable binding modes by polylactosamine-metabolizing enzymes, e.g., the midchain beta1,6-GlcNAc transferase (Leppänen et al., Biochemistry, 36, 13729-13735, 1997).

The evaluation of a low resolution fourier transform infrared (FTIR) gas analyser for monitoring of solvent emission rates under field conditions.

The applicability of a low resolution (8 cm-1) Fourier transform infrared (FTIR) gas analyser with an absorption path length of 3 m was evaluated for the on-line monitoring of organic solvent mixture emissions in a flexographic ink manufacturing plant. The on-line monitoring revealed that the highest variations of solvent concentrations, up to three decades, occurred in the exhaust air. The FTIR analyser with a dynamic range of four decades covers well the concentration ranges typically found in the exhaust air and in the workroom air of ink manufacturing plants. The average emission rate of solvent mixture based on a sampling period of two days was 1.8 kg h-1 consisting of mainly ethanol (70%), ethyl acetate (15%) and propan-2-ol (11%). The detection limits of the analyser for the solvent compounds ranged from 0.3 to 4.3 mg m-3 and the measurement uncertainty was less than 10% in the concentration range of 8-15,000 mg m-3. These characteristics make the apparatus appropriate for most industrial hygiene applications. An FTIR spectrophotometer, equipped with an multipoint sampling unit, facilitates rapid identification of solvent components, real-time display of concentration data relevant to workroom air and environment monitoring as well as process control. Furthermore, the on-line concentration information enabled a rapid selection of representative sampling locations. The spectrophotometer is transportable, rugged and relatively simple to calibrate even in a hostile industrial environment.

The centrally acting beta1,6N-acetylglucosaminyltransferase (GlcNAc to gal). Functional expression, purification, and acceptor specificity of a human enzyme involved in midchain branching of linear poly-N-acetyllactosamines.

In the present experiments the cDNA coding for a truncated form of the beta1,6N-acetylglucosaminyltransferase responsible for the conversion of linear to branched polylactosamines in human PA1 cells was expressed in Sf9 insect cells. The catalytic ectodomain of the enzyme was fused to glutathione S-transferase, allowing effective one-step purification of the glycosylated 67-74-kDa fusion protein. Typically a yield of 750 microg of the purified protein/liter of suspension culture was obtained. The purified recombinant protein catalyzed the transfer of GlcNAc from UDP-GlcNAc to the linear tetrasaccharide Galbeta1-4GlcNAcbeta1-3Galbeta1-4GlcNAc, converting the acceptor to the branched pentasaccharide Galbeta1-4GlcNAcbeta1-3(GlcNAcbeta1-6)Galbeta1-4 GlcNAc as shown by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, degradative experiments, and 1H NMR spectroscopy of the product. By contrast, the recombinant enzyme did not catalyze any reaction when incubated with UDP-GlcNAc and the trisaccharide GlcNAcbeta1-3Galbeta1-4GlcNAc. Accordingly, we call the recombinant beta1,6-GlcNAc transferase cIGnT6 to emphasize its action at central rather than peridistal galactose residues of linear polylactosamines in the biosynthesis of blood group I antigens. Taken together this in vitro expression of I-branching enzyme, in combination with the previously cloned enzymes, beta1,4galactosyltransferase and beta1, 3N-acetylglucosaminyltransferase, should allow the general synthesis of polylactosamines based totally on the use of recombinant enzymes.

Complementary acceptor and site specificities of Fuc-TIV and Fuc-TVII allow effective biosynthesis of sialyl-TriLex and related polylactosamines present on glycoprotein counterreceptors of selectins.

The P-selectin counterreceptor PSGL-1 is covalently modified by mono alpha2,3-sialylated, multiply alpha1,3-fucosylated polylactosamines. These glycans are required for the adhesive interactions that allow this adhesion receptor-counterreceptor pair to facilitate leukocyte extravasation. To begin to understand the biosynthesis of these glycans, we have characterized the acceptor and site specificities of the two granulocyte alpha1,3-fucosyltransferases, Fuc-TIV and Fuc-TVII, using recombinant forms of these two enzymes and a panel of synthetic polylactosamine-based acceptors. We find that Fuc-TIV can transfer fucose effectively to all N-acetyllactosamine (LN) units in neutral polylactosamines, and to the "inner" LN units of alpha2,3-sialylated acceptors but is ineffective in transfer to the distal alpha2,3-sialylated LN unit in alpha2,3-sialylated acceptors. Fuc-TVII, by contrast, effectively fucosylates only the distal alpha2,3-sialylated LN unit in alpha2,3-sialylated acceptors and thus exhibits an acceptor site-specificity that is complementary to Fuc-TIV. Furthermore, the consecutive action of Fuc-TIV and Fuc-TVII, in vitro, can convert the long chain sialoglycan SAalpha2-3'LNbeta1-3'LNbeta1-3'LN (where SA is sialic acid) into the trifucosylated molecule SAalpha2-3'Lexbeta1-3'Lexbeta1-3'Lex (where Lex is the trisaccharide Galbeta1-4(Fucalpha1-3)GlcNAc) known to decorate PSGL-1. The complementary in vitro acceptor site-specificities of Fuc-TIV and Fuc-TVII imply that these enzymes cooperate in vivo in the biosynthesis of monosialylated, multifucosylated polylactosamine components of selectin counterreceptors on human leukocytes.

Target levels--tools for prevention.

Although occupational exposure limits are sought to establish health-based standards, they do not always give a sufficient basis for planning an indoor air climate that is good and comfortable for the occupants in industrial work rooms. This paper considers methodologies by which the desired level, i.e., target level, of air quality in industrial settings can be defined, taking into account feasibility issues. Risk assessment based on health criteria is compared with risk-assessment based on "Best Available Technology" (BAT). Because health-based risk estimates at low concentration regions are rather inaccurate, the technology-based approach is emphasized. The technological approach is based on information on the prevailing concentrations in industrial work environments and the benchmark air quality attained with the best achievable technology. The prevailing contaminant concentrations are obtained from a contaminant exposure databank, and the benchmark air quality by field measurements in industrial work rooms equipped with advanced ventilation and production technology. As an example, the target level assessment has been applied to formaldehyde, total inorganic dust and hexavalent chromium, which are common contaminants in work room air.