Concentrations of potentially endocrine disrupting chemicals in car cabin air and dust - Effect of temperature and ventilation.

Materials in car cabins contain performance-enhancing semi-volatile organic compounds (SVOCs). As these SVOCs are not chemically bound to the materials, they can emit from the materials at slow rates to the surrounding, causing human exposure. This study aimed at increasing the understanding on abundance of SVOCs in car cabins by studying 18 potential endocrine disrupting chemicals in car cabin air (gas phase and airborne particles) and dust. We also studied how levels of these chemicals varied by temperature inside the car cabin along with ventilation settings, relevant to human exposure. A positive correlation was observed between temperature and SVOC concentration in both the gas and the particle phase, where average gas phase levels at 80 °C were a factor of 18-16,000 higher than average levels at 25 °C, while average particle phase levels were a factor of 4.6-40,000 higher for the studied substances. This study also showed that levels were below the limit of detection for several SVOCs during realistic driving conditions, i.e., with the ventilation activated. To limit human exposure to SVOCs in car cabins, it is recommended to ventilate a warm car before entering and have the ventilation on during driving, as both temperature and ventilation have a significant impact on SVOC levels.

Assessing exposure of semi-volatile organic compounds (SVOCs) in car cabins: Current understanding and future challenges in developing a standardized methodology.

Semi-volatile organic compounds (SVOCs) can be found in air, dust and on surfaces in car cabins, leading to exposure to humans via dust ingestion, inhalation, and dermal contact. This review aims at describing current understanding concerning sampling, levels, and human exposure of SVOCs from car cabin environments. To date, several different methods are used to sample SVOCs in car cabin air and dust and there are no standard operating procedures for sampling SVOCs in cars detailed in the literature. The meta-analysis of SVOCs in car cabin air and dust shows that brominated flame retardants (BFRs) and organophosphate flame retardants (OPFRs) have been most frequently studied, primarily focusing on concentrations in dust. In dust, detected concentrations span over three to seven orders of magnitude, with highest median concentrations for OPFRs, followed by BFRs and, thereafter, polychlorinated biphenyls (PCBs). In air, the variation is smaller, spanning over one to three orders of magnitude, with phthalates and siloxanes having the highest median concentrations, followed by OPFRs, fluorotelomer alcohols (FTOHs) and BFRs. Assessments of human exposures to SVOCs in cars have, so far, mainly focused on external exposure, most often only studying one exposure route, primarily via dust ingestion. In order to perform relevant and complete assessments of human exposure to SVOCs in cars, we suggest broadening the scope to which SVOCs should be studied, promoting more comprehensive external exposure assessments that consider exposure via all relevant exposure routes and making comparisons of external and internal exposure, in order to understand the importance of in-car exposure as a source of SVOC exposure. We also suggest a new sampling approach that includes sampling of SVOCs in both car cabin air and dust, aiming to reduce variability in data due to differences in sampling techniques and protocols.

PM2.5 and ultrafine particles in passenger car cabins in Sweden and northern China-the influence of filter age and pre-ionization.

The main aim of the study was to evaluate the influence of filter status (new and aged), pre-ionization, on the particle filtration in modern passenger cars. Measurements of in-cabin and outside PM2.5 (dp < 2.5 µm) concentration and UFP (ultrafine particle, dp < 100 nm) counts, to calculate I/O (indoor to outdoor) ratios, were performed. They were done at two locations, to study the influence of different outside conditions on the HVAC (heating, ventilation, and air-conditioning) system. The measurements were performed in two new cars, with similar HVAC systems and settings, using a new filter and an aged synthetic filter. Furthermore, an ionization unit was installed upstream of the filter in both cars. This enabled the study of filter status, with and without ionization, under common driving conditions. The results show that the HVAC system performances were very similar at the two locations, with average I/O ratios of 0.35-0.40 without ionization and 0.15-0.20 with ionization applied, although the outside conditions were considerably different. Furthermore, the aged filter clearly worsened the filtration ability. Considering the corresponding average PM2.5 I/O ratios in one location as an example, the average for the new filter was 0.20 and 0.60 for the aged filter. The corresponding UFP I/O ratios were 0.24 and 0.57. Other findings are that the aged filter with ionization reached a performance close to the new filter (without ionization), and that increased ventilation airflow and decreased recirculation degree, as expected, led to an increase in the I/O ratio for both particle sizes.