Monitoring of volatile organic compounds in non-residential indoor environments

A weekly monitoring campaign of volatile organic compounds (VOC), with single sampling of 24 h, was carried out in non-residential indoor environments such as libraries, pharmacies, offices, gymnasiums, etc., in order to evaluate the VOC concentrations to which people are exposed. Moreover, an outdoor sample was coupled to each indoor site to point out the influence of indoor sources. They were sampled with Radiello diffusive samplers for thermal desorption and analyzed by GC-MS. As already described in other papers, the VOC levels of most of the indoor sites were higher than that observed in the corresponding outdoor sites. For example, some sites showed a level of pollution that is ten times higher than their corresponding outdoor site. The monitored environments that had higher concentrations of the investigated VOC were the pharmacies, a newspaper stand, a copy center, and the coffee shops. Analysis of the weekly average concentrations of each pollutant and the use of literature allowed pointing out some site-specific characteristics that singled out possible sources of VOC. These results were verified analyzing the indoor-outdoor ratio (I/O) too. Newspaper stands were characterized by very high concentrations of toluene and pharmacies were characterized by high concentrations of aromatic compounds. PRACTICAL IMPLICATIONS: Indoor air pollution caused by volatile organic compounds (VOC) might affect human health at home as well as in public and commercial buildings. The main VOC sources in indoor environments are human activities, personal care products, smoking, house cleaning products, building products, and outside pollution. To preserve human health it is necessary to evaluate the average concentrations of VOC to which people are exposed and to identify the main sources of indoor pollution by means of suitable indoor monitoring campaigns in several environments. These investigations allow pointing out the characteristic critical situations of some indoor environments or some other types of environments.     

Test chamber investigation of the volatilization from source materials of brominated flame retardants and their subsequent deposition to indoor dust

Numerous studies have reported elevated concentrations of brominated flame retardants (BFRs) in dust from indoor micro‐environments. Limited information is available, however, on the pathways via which BFRs in source materials transfer to indoor dust. The most likely hypothesized pathways are (a) volatilization from the source with subsequent partitioning to dust, (b) abrasion of the treated product, transferring microscopic fibers or particles to the dust (c) direct uptake to dust via contact between source and dust. This study reports the development and application of an in‐house test chamber for investigating BFR volatilization from source materials and subsequent partitioning to dust. The performance of the chamber was evaluated against that of a commercially available chamber, and inherent issues with such chambers were investigated, such as loss due to sorption of BFRs to chamber surfaces (so‐called sink effects). The partitioning of polybrominated diphenyl ethers to dust, post‐volatilization from an artificial source was demonstrated, while analysis in the test chamber of a fabric curtain treated with the hexabromocyclododecane formulation, resulted in dust concentrations exceeding substantially those detected in the dust pre‐experiment. These results provide the first experimental evidence of BFR volatilization followed by deposition to dust.     

气相色谱法测定TVOC操作条件的选择（热解吸法）

介绍了通过改变热解吸时间、色谱柱温度和进样时间来控制室内空气中有害气体TVOC的测定条件,以达到最佳测定结果,结果证实可以取得稳定而满意的测定数据。     

Emissions of volatile organic compounds from polymer-based consumer products: Comparison of three emission chamber sizes

The ISO 16000 standard series provide guidelines for emission measurements of volatile organic compounds (VOCs) from building materials. However, polymer-based consumer products such as toys may also release harmful substances into indoor air. In such cases, the existing standard procedures are unsuitable for official control laboratories due to high costs for large emission testing chambers. This paper aims at developing and comparing alternative and more competitive methods for the emission testing of consumer products. The influence of the emission chamber size was investigated as smaller chambers are more suited to the common size of consumer products and may help to reduce the costs of testing. Comparison of the performance of a 203 L emission test chamber with two smaller chambers with the capacity of 24 L and 44 mL, respectively, was carried out by using a polyurethane reference material spiked with 14 VOCs during the course of 28 days. The area-specific emission rates obtained in the small chambers were always similar to those of the 203 L reference chamber after a few hours. This implies that smaller chambers can provide at least useful numbers on the extent of polymer-based consumer product emissions into indoor air, thereby supporting meaningful exposure assessments.     

Simulation of VOC emissions from building materials by using the state-space method

There are many mass-transfer models for predicting VOC emissions from building materials described in the literature. In these models, the volatile organic compound (VOC) emission rate and its concentration in a chamber or a room are usually obtained by analytical method or numerical method. Although these methods demonstrate some salient features, they also have some flaws, e.g., for analytical method the solutions of both room or chamber VOC concentration and building material VOC emission rate are constituted of the sum of an infinite series, in which additional computation for finding roots to a transcendental function is necessary, but sometimes quite complicated. Besides, when it is applied in complex cases such as multilayer emission with internal reaction, the solution is very difficult to get; for conventional numerical methods such as finite difference method, discrete treatment of both time and space may cause calculation errors. Considering that, the state-space method widely used in modern automation control field and the heat transfer field is applied to simulate VOC emissions from building materials. It assumes that a slab of building material is composed of a number of finite layers, in each of which the instantaneous VOC concentration is homogenous during the entire process of emission, while the time is kept continuous. Based on this assumption we can predict both the VOC emissions rate and the concentrations of VOCs in the air of a chamber or room. The method is generally applied to simulate VOC emissions from arbitrary layers of building materials, and the solution is explicit and simple. What's more, the method can be applied to the cases where a reaction producing/removing VOC in building materials exists. For some specific cases the method is validated using the experimental data and the analytical solutions in the literature. The method provides a simple but powerful tool for simulating VOC emissions from building materials, which is especially useful in developing indoor air quality (IAQ) simulation software.