Particulate Matter In Indoor Environments Research Articles

PARTICULATE RESUSPENSION DURING THE USE OF VACUUM CLEANERS ON OFFICE CARPETS IN UNIVERSITI MALAYSIA TERENGGANU

The household activities such as vacuuming may elevate the concentration ofparticulate matter in indoor environments. Cleaning workers and occupants inside closed room may be exposed to the fine particulate matter and at risk of developing numerous respiratory symptoms. This study aims to determine the concentration of the particulate matter (PM10 and PM2.5) that might arise during vacuuming activities and estimated the surface compartmental residence time of particulate matter in indoor environment after each vacuuming activities. The PM10 and PM2.5 concentrations throughout vacuuming were measured in forty-seven offices in Universiti Malaysia Terengganu using the TSI Dust Track DRX. Based on the concentrations measured, the surface compartmental residence time was then estimated using standardized equations taken from literature. The result shows that highest particulate matter concentration was nearly eleven times higher than the World Health Organization guidelines of 25 μg/m3 for PM2.5 concentration (PM2.5 was 270μg/m3, PM10 was 421 μg/m3), while the particulate matter were estimated to remain lingers inside the air for around 1-4 days before being deposited on the surface. In conclusion, the usage of vacuum cleaners may contribute to more particulate matter being released inside the air due to the resuspension phenomenon. Therefore, it is important for the occupants to maintain proper ventilation after each vacuuming activities took place.

Assessment of Chemical Fiber Air Filter for General Ventilation

Air filters for general ventilation have mainly been used to control the concentration of indoor particulate matter. In this study, the pressure differential, test dust capacity, quality factor and operating life of class F8 pleat–plate and multi-bag type chemical fiber filters were evaluated using an air filter performance test system. The results showed that the resistance increase rate of multi-bag filter (0.49 Pa/g·(cm/s)) was lower than that of pleat–plate filter (1.94 Pa/g·(cm/s)), the quality factor of the multi-bag filter was lower than that of pleat–plate filter, and the dust capacity of the multi-bag filter was much higher than that of the pleat–plate filter. The operating life of the multi-bag filter was 8 times as that of the pleat–plate filter with the measured PM2.5 of outdoor. The energy consumption of the pleat–plate filter was 2.2 times that of the multi-bag filter. Analyzing the electron microscope photos after dust loading, the dust depth of pleat–plate filter into filter material was thinner than that of multi-bag filter. The research results could provide data support for the design optimization and selection of ventilation filters and the treatment of the particulate matter in indoor environments.

Volatile organic compound and particulate matter emissions from an ultrasonic essential oil diffuser.

Ultrasonic essential oil diffusers (EODs) are a popular type of indoor scenting source. We performed a chamber study in which we measured the emissions from EODs used with lemon, lavender, eucalyptus, and grapeseed oils. Over the course of 15min, the most abundant VOCs released from lemon, lavender, eucalyptus, and grapeseed oils were 2.6±0.7mg of d-limonene, 3.5±0.4mg of eucalyptol, 1.0±0.1mg of linalyl acetate, and 0.2±0.02mg of linalyl acetate, respectively. Each oil had a unique particulate matter (PM) emission profile in terms of size, number density, and rate. The dominant size ranges of the PM were 10-100nm for lemon oil, 50-100nm for lavender oil, 10-50nm for lemon oil, and above 200nm for grapeseed oil. PM1 emission rates of approximately 2mg/h, 0.1mg/h, and 3mg/h, were observed for lemon, lavender/eucalyptus, and grapeseed oils, respectively. A fivefold increase in PM1 emission was measured when the EOD with eucalyptus oil was filled with tap water as opposed to deionized water. Modeling suggests that reasonable use cases of EODs can contribute substantially to primary and secondary PM in indoor environments, but this potential varies depending on the oil and water types used.

Size Distribution of Particulate Matter in Indoor Environment During Nanomaterial Paint Application

Due to the increasing production and development of nanoparticles, it has become necessary to control the exposure to ultrafineparticles (aerodynamic diameter < 0.1 μm) when handling nanopaints. The paper deals with the number and mass distributionof particulate matter (PM) in an indoor environment before, during and after the application of paint Protectam FN containingtitanium nanoparticles. The size distribution determination was performed by the electrical low-pressure cascade impactor (ELPI+)in the range from 0.006 μm to 9.93 μm. The highest number of particles was observed in the range from 0.006 to 0.0175 μm. Theparticulate mass concentration ranging from 0.0175 to 0.0307 μm did not represent more than 0.5% of the sum of PM10 during theindividual measurements. The particle mass concentration increased in the range of 0.0175 to 0.0307 μm, after application of thecoating nanopaint Protectam FN, but it was observed that the total number of particles has decreased. During the days followingthe application of the nanopaint, the mass concentration in this grain size class was significantly reduced.

The impact of airflow and air purification on the resuspension and removal of deposited particulate matter

Air purifiers are a popular tool to manage indoor particulate matter; however, their effectiveness with respect to resuspending and removing particles that have been deposited on surfaces is limited. This study proposed and evaluated a method of removing both suspended and deposited particulate matter using an air purifier in conjunction with an airflow source. First, the effectiveness of the air purifier with respect to removing deposited particulate matter was determined in a static environment and under forced airflow. Then, the removal efficiency of the purification system was evaluated under varying airflow orientations and velocities. Results showed that the air purifier contributed to particulate matter resuspension and removal, and the efficiency was significantly improved under forced resuspension due to airflow generation. The orientation of the airflow was found to have an impact on the resuspension and removal efficiency of particulates, and four-way airflow was more effective compared to one-way airflow. This was attributed to four-way flow increasing the airflow diffusion radius compared to one-way flow. A flow velocity of 5 m/s or greater was necessary to resuspend deposited particulate matter. These findings illustrate that forced resuspension is an effective means of reducing deposited particulate matter in indoor environments, and four-way airflow with a wide diffusion radius and a velocity of 5 m/s or higher are the optimum conditions for this purpose.

Measurement of Surface Area Concentration of Fine Particulate Matter in Indoor Environments

Indoor exposure to fine particles (0.01-2.5 µm) is measured in the present study using Surface Area Concentration (SAC) metric for two indoor environment categories based on the cooking fuel used—kerosene and Liquid Petroleum Gas LPG. Study of SAC is very important from the point of view of health aspects. From the collected data, Arithmetic Means, Geometric Means, peak concentration values were determined to compare between the two categories of Indoor environment. The results show the two environments to be significantly different. Also, the results indicate remarkable high indoor surface area concentrations during the cooking and other combustion processes.

Air filters for indoor environments: Interlaboratory evaluation of the new international filter testing standard ISO 16890.

Electret filters are widely used in HVAC systems to decrease particulate matter in indoor environments. The previous standard in Europe for testing air filters for general ventilation was EN 779. In July 2018, it was replaced by the new international standard ISO 16890. One major change is the discharging process: It is now performed by treating the filters with saturated isopropyl alcohol (IPA) vapor. The process is intended to simulate a worst-case scenario of the filtration efficiency due to the reduction of the electret effect. These minimal efficiencies are a principal part of the filter classification. Therefore, two round robin tests with different filter classes (F9 and F7 according to EN 779) and up to eleven participants were carried out to evaluate the new test method by comparing the filtration efficiencies and pressure drops before and after the IPA treatment. Pressure drop measurements showed no mechanical altering of the material due to the discharging process. The calculated filter classes had a maximum deviation of 5%. Even with different equipment, the results indicate that the new ISO 16890 seems to be a viable test standard and a decent replacement for previous national standards.

Measurements and analysis of adhesive forces for micron particles on common indoor surfaces

Dust particle resuspension from indoor surfaces is an important source of particulate matter in indoor environments. The adhesive force represents the resistance of the particle to resuspension in an air stream and is a key factor in the resuspension process. The present study used an atomic force microscope (AFM) to measure the adhesive forces between three particle samples and four common indoor surfaces including acrylic, marble, epoxy flooring and wood flooring. The effects of different indoor surfaces were investigated using 12 particle–surface combinations. The results show that the average adhesive forces range from 8.2 nN to 448.1 nN for different combinations with the surface roughness being the main factor. The average adhesive force increases with the contact radius and is larger on the wood flooring surface than on the other three surfaces. Then, the resuspension process was simulated using the moment balance method with the measured adhesive forces as the model inputs. The model predictions show that the wood flooring surface has the largest resistance to the air flow entrainment, followed by the epoxy flooring surface, then the marble surface and the least is the acrylic surface.

Removal of polycyclic aromatic hydrocarbons and genotoxic compounds in urban air using air filter materials for mechanical ventilation in buildings

Humans spend most of their lives in indoor environments; hence, indoor exposure to air pollution may constitute a large part of the total exposure to air pollution. Polycyclic aromatic hydrocarbons are well known for their mutagenicity and carcinogenicity and are ubiquitous in urban environments as a result of combustion from e.g. vehicular traffic. Polycyclic aromatic hydrocarbons associated to air particulate matter in indoor environments originates from several sources including: cooking and heating, outdoor sources, smoking, candle and incense burning. Infiltration has been suspected to be one major source of indoor polycyclic aromatic hydrocarbons. In this study, four different air filter materials intended for mechanical ventilation were tested for their capability to remove particle bound polycyclic aromatic hydrocarbons and other genotoxic compounds from a real urban aerosol. Particles were sampled at two highly trafficked locations in Stockholm using a sampling system capable of sample particles in parallel, thus allowing sampling of filtered and un-filtered air simultaneously. The sampled particles were extracted and analysed for polycyclic aromatic hydrocarbons and the genotoxicity of the organic extract was determined using Ames mutagenicity tests. Each air filters capability of removing polycyclic aromatic hydrocarbons and reducing genotoxic effects was determined by comparing the filtered and un-filtered air samples. The results showed that all air filter materials had the capability of removing polycyclic aromatic hydrocarbons and reduce genotoxic effects downstream the air filter, and that the magnitude of the reduction was correlated with the standardized particulate collection efficiencies of a 0.4 μm particles for the tested air filter materials. However, the filter with the lowest performance did not significantly reduce direct acting mutagens.

Study of metals in radical-mediated toxicity of particulate matter in indoor environments of Pune, India

The concentration of coarse and fine indoor particulate matter (PM) was measured along with that of metals (Fe, Cu, Zn, Mn, Pb, Cd, Co, Ni, and Cr) collected from rural and urban residential environments of Pune City with the purpose of examining their free radical generation and its related toxicity. The average mass concentration of indoor PM10 and PM2.5 was ∼3.3 and ∼4.5 times higher than the threshold limits of the Indian National Ambient Air Quality Standards (NAAQS) at urban and rural sites, respectively. The concentration of metals was found to be higher in the fine fraction of PM collected from the rural site. Metal analysis revealed the dominance of Fe concentrations in both PM10 and PM2.5 followed by Zn, Ni, and Cu. Electron paramagnetic resonance (EPR) was used to evaluate the presence of free radicals in samples collected from both the sites. EPR spectra for these particles were attributed to both Fe3+ (g = 1.99∼2.0) and free radicals (g = 2.0023 and g = 2.003) in PM samples. Dithiothreitol (DTT) assay was also performed which supports the presence of higher redox activity in the fine fraction of PM at the rural site. Significant DNA damage was observed by both fractions of PM when tested in the controlled experiment, with averages of 43 and 30.9 % for PM10 and 55.3 and 40.5 % for PM2.5 at the rural and urban sites, respectively. This study articulates a significant amount of evidence to understand the importance of size and composition (especially metals) of indoor PM in the toxicological mechanism.

Particle size distributions and concentrations above radiators in indoor environments: Exploratory results from Xi'an, China

Particulate matter in indoor environments has caused public concerns in recent years. The objective of this research is to explore the influence of radiators on particle size distributions and concentrations. The particle size distributions as well as concentrations above radiators and in the adjacent indoor air are monitored in forty-two indoor environments in Xi’an, China. The temperatures, relative humidity and air velocities are also measured. The particle size distributions above radiators at ten locations are analyzed. The results show that the functional difference of indoor environments has little impact on the particle size distributions above radiators. Then the effects of the environmental parameters (particle concentrations in the adjacent indoor air, temperatures, relative humidities and air velocities) on particle concentrations above radiators are assessed by applying multiple linear regression analysis. Three multiple linear regression models are established to predict the concentrations of PM10, PM2.5 and PM1 above radiators.

Particulate matter investigation in indoor environment

Particulate matter is one of the most important indoor air pollutants involved in a number of adverse health effects, such as premature deaths and increased mortality of infants and other parts of sensitive population. This paper focuses on investigation of metal substances of suspended as well as settled particulate matter in indoor environment. The monitoring of particulate matter concentration was carried out in three rooms of a selected flat building in the city of Košice, Slovakia. The sampling of settled particulate matter was carried out by passive methods during the period of 28 days. The investigation of suspended particulate matter investigation focused on total suspended particles (TSP) and thoracic fraction called PM10. The presence of selected metals in the samples was detected by atomic absorption spectrometry. The surface concentrations of settled particulate matter were detected in the range from 276.43 μg cm-2 to 570.70 μg cm-2, mass concentrations of total suspended particulate matter from 59.028 to 114.583 μg m-3. PM10 concentration values reached about half of the TSP concentration values (PM10/TSP ratio was from 0.48 to 0.6). Higher percentage of metals was detected in suspended particulate matter in comparison to the settled particles. Higher values were detected for all metals (except iron and zinc) in each measured room.

Partikuläre Belastungssituation in Innenräumen, unter besonderer Berücksichtigung von Wohninnenräumen, Gemeinschaftseinrichtungen und Gaststätten

Numerous epidemiological studies have been carried out during the last decades which have demonstrated an association between the pollution of outside air with toxic substances and the occurrence of health-related effects. Against the background of these findings, particularly in recent years, the focus of research has clearly shifted towards particulate matter (PM), notable fine and ultrafine particles. While diverse measurements of PM in the outside air have been conducted, only few data on indoor air pollution are available. The concentration of PM in the indoor environment is highly variable in time and space due to various influencing factors like type of the source, building and room characteristics, the activities of users and the airing behaviour. In this article we aim to summarise and discuss the exposure situation regarding PM in indoor environments. In residences, European studies have found mean PM (2.5) values between 10 and 87 microg/m (3). Especially in smokers' homes, a high background level was observed, reaching very high concentrations of some hundred microg/m (3) when active smoking took place. There are some studies on air quality in schools and similar public places which show that exposure to particulate matter in these environments is high. The main causes of this situation appear to be an insufficient ventilation routine as well as the low frequency and quality of cleaning. In combination with the high number of pupils in relation to room area and volume and their sometimes high physical activity, this leads to a continued resuspension of particles from the room's surfaces. A very high concentration of PM can be observed in those recreational places where smoking is not prohibited, such as discotheques, pubs and restaurants. Here, the mean PM values can reach some hundred microg/m (3). Specific strategies are necessary to especially protect the health of non-smokers in such places. Further investigations are needed to characterise the composition of indoor particles and their toxicological properties compared to particles from outdoor origin.

Measurement of vertical concentration profiles of airborne particulate matter in indoor environments: Implications for refinement of models and monitoring campaigns

Vertical concentration profiles of airborne particulate matter were measured in four different indoor environments- library, coffee room, workshop and undergraduate student hostel- on the University Campus at Sutton Bonington. Measurements were carried out using an electronically-controlled lifting platform carrying a real-time optical particle monitor for sampling air sequentially at different heights within the breathing zone. Data was automatically logged at the different receptor levels, for the determination of the average vertical concentration profile of the various particle size ranges which include inhalable, thoracic, alveolic, PM10 and PM2.5. Vertical concentration profiles measured in these different indoor environments exhibited different characteristics but in almost all cases it was clear that different height groups of the population are exposed to different concentrations of the pollutant. This has implications on setting of air quality standards for the protection of public health. The results indicate that we may have to re-think the whole concept of air quality standards and develop protocols for indoor air quality monitoring and modelling which would take into account the above-mentioned factor.