Exposures to volatile nitrosamines were measured at 24 rubber manufacturing plants from 1992 to 1995. A total of 709 exposure measurements were taken in general areas or personal breathing zones to estimate exposure according to production types (seals, joints, tyres, gloves, etc.) and production steps, from mixing to storage. Five different nitrosamines were identified. N-Nitrosodimethylamine is the most frequently encountered nitrosamine and represents the most important fraction of the total nitrosamine concentration measured in a given sample. This fact is consistent with the use of rubber additives containing corresponding amine precursors. One hundred and forty-one of the 709 values exceeded the German target value (TRK) of 2.5 micrograms/m3 for all nitrosamines present from rubber vulcanisation, the only available standard for occupational nitrosamine exposures. The salt bath curing process generates particularly high nitrosamine levels, 90% of the 96 measurements being over the TRK, with many values exceeding 20 micrograms/m3. The reasons why the TRK is exceeded are generally well identified. To reduce nitrosamine emission levels it would be advisable to eliminate nitrogen oxide sources, principally by using a process other than salt bath curing, and to develop different rubber stocks that do not contain secondary aliphatic amine functional groups ("safe amines").

Diffusive sampling is particularly suited to determine time-weighted average volatile organic compound (VOC) concentration in occupational hygiene and environmental air monitoring. The purpose of this study was to measure the sampling rate variation of four different samplers in a special use--the exposure to a low concentration of volatile organic compound (10 to 200 ppb) for a long period (1 to 14 days). PerkinElmer tube-type adsorbent was packed with Tenax TA and RADIELLO cartridge packed with Carbograph 4. Badge-type activated carbon diffusive samplers 3M 3500 and GABIE were exposed to the same controlled atmospheres of benzene as meta-xylene (BTX) during the same exposure times. Performance samplers were observed for variability of uptake rates according to concentration levels, exposure duration, back diffusion, and competition phenomena at the adsorption sites. Particular benzene behavior has been noted for the thermally desorbable tube-type diffusive sampler: the measured sampling rates decrease with time following an exponential profile. With badge-type active charcoal diffusive samplers, the uptake rates were found to be highly stable and unaffected by time exposure. Overall, in the region of a few tens of ppb, for long-time exposure and for the lightest compounds, 3M 3500 and GABIE diffusive samplers seem the most appropriate diffusive sampling technique in terms of performance and facility in use.

Polymers processed to produce plastic articles are subjected to temperatures between 150°C and 450°C or more during overheated processing and breakdowns. Heat-based processing of this nature can lead to emission of volatile organic compounds (VOCs) into the thermoplastic processing shop. In this study, laboratory experiments, qualitative and quantitative emissions measurement in thermoplastic factories were carried out. The first step was to identify the compounds released depending on the thermoplastic nature, the temperature and the type of process. Then a thermal degradation protocol that can extrapolate the laboratory results to industry scenarios was developed. The influence of three parameters on released thermal breakdown products was studied: the sample preparation methodsmanual cutting, ambient or cold grinding -the heating rate during thermal degradation -5, 10 20 and 50°C/min -and the decomposition method -thermogravimetric analysis and pyrolysis. Laboratory results were compared to atmospheric measurements taken at 13 companies to validate the protocol and thereby ensure its representativeness of industrial thermal processing. This protocol was applied to most commonly used thermoplastics to determine their thermal breakdown products and their thermal behaviour. Emissions data collected by personal exposure monitoring and sampling at the process emission area show airborne concentrations of detected compounds to be in the range of 0-3 mg/m 3 under normal operating conditions. Laser cutting or purging operations generate higher pollution levels in particular formaldehyde which was found in some cases at a concentration above the workplace exposure limit.3

To avoid multiple instruments to be deployed in field measurement campaigns based on airborne nanoparticles characterization, this study aims at investigating the capability of a Scanning Mobility Particle Sizer (SMPS) to provide accurate data relative to the mass concentration. Two series of test nanoaerosols were produced using a spark-discharge generator equipped with carbon or titanium electrodes (modal number diameters between ~ 50 and ~ 170 nm). The mass concentration was monitored by means of a personal AM520 photometer operated in parallel with the SMPS and closed-face cassette sampling for further off-line analysis: gravimetric analysis, and chemical analysis (thermo-optical analysis for carbon, ICP-OES for titanium). For each operating condition, the average number size distribution stemming from the SMPS was converted into mass size distribution accounting for particle effective density and integrated over the whole range of particle diameters to determine the corresponding mass concentration. Results highlight correlations (R2 ~ 0.9) between SMPS-based and chemical analysis or gravimetric mass concentrations below 1 mg/m3, with relative discrepancies lower than ~ 15% and ~ 25%, respectively. The AM520 photometric response remains dependent on particle physical and light scattering properties, which differ with the test dust used for factory calibration.