Quantification and characterisation of suspended particulate matter in indoor air

Effects of mono-2-ethylhexyl phthalate on the respiratory tract in BALB/c mice

Airborne mono-2-ethylhexyl phthalate (MEHP) was studied for acute airway effects using a bioassay with BALB/c mice. Concentration-and time-dependent effects were obtained by continuous monitoring of the breathing pattern during exposure to 0.3-43.6 mg/m3 MEHP for 60 min. Additionally, inflammatory effects of MEHP were studied from bronchoalveolar lavage (BAL) fluid. MEHP showed no upper airway irritating effect. Lower airway irritation was apparent from a concentration-dependent decrease in tidal volume (shallow respiration) with a no-observed effect level (NOEL) of 0.3 mg/m3. The respiratory rate reached a maximum at about 8 mg/m3, demonstrating a rapid shallow breathing pattern. At concentrations above 4.9 mg/m3, the time of pause, another marker of lung irritation, increased concentration-dependently, resulting in a decrease in respiratory rate at high exposure levels. BAL fluid obtained from 0 to 72 hours after a 60 min exposure to 30 mg/m3 MEHP showed that the number of macrophage reached maximum about 16 hours after exposure. The NOEL was 1.7 mg/m3. BAL content of neutrophils, lymphocytes, eosinophils and epithelial cells was normal after exposure to 30 or 1.7 mg/m3 MEHP. Based on worst case inhalation scenario in the general population, no airway irritation is expected from non-occupational levels of MEHP originating from DEHP.

Monetary Valuation of PM10-Related Health Risks in Beijing China: The Necessity for PM10 Pollution Indemnity

Severe health risks caused by PM₁₀ (particulate matter with an aerodynamic diameter ≤10 μm) pollution have induced inevitable economic losses and have rendered pressure on the sustainable development of society as a whole. In China, with the “Polluters Pay Principle”, polluters should pay for the pollution they have caused, but how much they should pay remains an intractable problem for policy makers. This paper integrated an epidemiological exposure-response model with economics methods, including the Amended Human Capital (AHC) approach and the Cost of Illness (COI) method, to value the economic loss of PM₁₀-related health risks in 16 districts and also 4 functional zones in Beijing from 2008 to 2012. The results show that from 2008 to 2012 the estimated annual deaths caused by PM₁₀ in Beijing are around 56,000, 58,000, 63,000, 61,000 and 59,000, respectively, while the economic losses related to health damage increased from around 23 to 31 billion dollars that PM₁₀ polluters should pay for pollution victims between 2008 and 2012. It is illustrated that not only PM₁₀ concentration but also many other social economic factors influence PM₁₀-related health economic losses, which makes health economic losses show a time lag discrepancy compared with the decline of PM₁₀ concentration. In conclusion, health economic loss evaluation is imperative in the pollution indemnity system establishment and should be considered for the urban planning and policy making to control the burgeoning PM₁₀ health economic loss.

The Progress in Electron Microscopy Studies of Particulate Matters to Be Used as a Standard Monitoring Method for Air Dust Pollution

The present article reviews studies on air solid particles carried out with the use of electron microscopy. Particle analysis combining scanning and transmission electron microscopy (SEM and TEM) can be used to derive size-resolved information of the composition, mixing state, morphology, and complex refractive index of atmospheric aerosol particles. It seems that electron microscopy is more widely used in atmospheric particulate matter analysis, but the usage of this method is sometimes problematic. First of all, there is no standard methodology adapted for dust analysis, and it is difficult to compare the results coming from different laboratories. Nevertheless, it was shown that this method has potential to be used in the future as a standard monitoring procedure of air solid particles.

Fouling of nanostructured insect cuticle: adhesion of natural and artificial contaminants

The adhesional properties of contaminating particles of scales of various lengths were investigated for a wide range of micro- and nanostructured insect wing cuticles. The contaminating particles consisted of artificial hydrophilic (silica) and spherical hydrophobic (C(18)) particles, and natural pollen grains. Insect wing cuticle architectures with an open micro-/nanostructure framework demonstrated topographies for minimising solid-solid and solid-liquid contact areas. Such structuring of the wing membranes allows for a variety of removal mechanisms to contend with particle contact, such as wind and self-cleaning droplet interactions. Cuticles exhibiting high contact angles showed considerably lower particle adhesional forces than more hydrophilic insect surfaces. Values as low as 3 nN were recorded in air for silica of ~28 nm in diameter and <25 nN for silica particles 30 μm in diameter. A similar adhesional trend was also observed for contact with pollen particles.

Application of visible, near-infrared, and short-wave infrared (400-2500 nm) reflectance spectroscopy in quantitatively assessing settled dust in the indoor environment. Case study in dwellings and office environments

The aim of this study was to apply a novel sensitive technique, involving reflectance spectroscopy in the 400-2500-nm region, to assess dust loads. A spectral library was created to enable identification of the possible sources of settled dust in indoor samples -- mineral versus organic-anthropogenic. Two field experiments were carried out at different dates, the first in dwellings and the second in office environments. Two main spectral patterns were found. Type A spectra indicate a high proportion of minerals in the sample and are characteristic of dust samples taken from the dwelling environment during April (when there were 5 dust storm events). Type B spectra denote a high proportion of organic matter in the sample and are characteristic of the dust samples taken from the offices during March (when there were only 2 dust storm events). The spectral shape within the visible range can be used to estimate the relative amount of mineral and organic components in the sample. Multivariate data analysis, based on Partial Least Squares (PLS) regression, was utilized to predict the relationship between the reflectance of a dust sample and its mass. The relative Root Mean Square Error of Predictions (%RMSEP) generated for the dust sampled in dwellings (6.5%) and offices (7.0%) are quite impressive considering the relatively small amounts of settled dust and its precise gravimetric weight accurate to +/-0.01 mg (min and max values are 0.1-3.2 mg). In addition, PLS regression analysis was used to identify which variables influence dust load. Possible applications of the proposed method are discussed.

Do indoor chemicals promote development of airway allergy?

Allergic asthma has increased worldwide in the industrialized countries. This review evaluates whether the major groups of indoor chemical exposures possess allergy-promoting (adjuvant) effects; formaldehyde was excluded, because of the size of the literature. Volatile organic compounds (VOCs) are used as an example of gases and vapors. The precipitation of asthmatic symptoms by VOC exposures is probably because of VOC levels considerably above typical indoor levels, or VOCs may be a surrogate for exposure to allergens, combustion products or dampness. Indoor particles possessed adjuvant effects in animal studies and allergy-promoting effects in humans. Quaternary ammonium compounds may possess adjuvant effects in animal studies and promoted sensitization in humans in occupational settings. The use of cleaning agents, anionic and non-ionic surfactants are not considered to possess an important adjuvant effect in the general population. Regarding phthalate exposures, results from animal and epidemiological studies were found to be discordant. There is little evidence that the indoor chemicals evaluated possess important adjuvant effects. If buildings are kept clean, dry and free of combustion products, the important question may be would it be profitable to look for lifestyle factors and non-chemical indoor exposures in order to abate airway allergy?

PRACTICAL IMPLICATIONS

Indoor chemicals (pollutants) have been accused to promote development of airway allergy by adjuvant effects. In this review, we evaluated the scientific literature and found little support for the supposition that indoor chemicals possess important adjuvant effects. This rises the question: would it be profitable for abatement of airway allergy to look for non-chemical indoor exposures, including lifestyle factors, and exposures to allergens, microorganisms, including vira, and their interactions?

Detection of allergens adsorbed to ambient air particles collected in four European cities

Air pollution has been implicated as one of the factors responsible for the increased incidence of allergic diseases observed in recent years. High concentrations of air pollutants may promote airway sensitization by acting as adjuvants. Ambient particles as carriers of adsorbed allergens are, therefore, of special interest since they may act as mediators of inflammatory as well as allergic responses. Ambient air particles from four cities in Europe were collected, in three different seasons, to examine the variation of allergens and their possible binding to the pollution particles. The particle fraction, PM10, was collected on polycarbonate filters using a low-volume sampling regime. The presence of pollen allergens, latex and beta-glucans was investigated using an immunogold labelling method directly on the collection filters. Scanning electron microscopy revealed mainly the classical carbon particles and aggregates determined to originate from vehicle exhaust. The immunogold labelling visualised in the backscatter electron imaging mode, showed that allergens from pollens, latex and also beta-glucans were bound to and, hence, transported by the combustion particles in ambient air. Thus, combustion particles in ambient air are carriers of allergens and act as depots of allergens inhaled into the airways.

Hospital indoor PM10/PM2.5 and associated trace elements in Guangzhou, China

PM10 and PM2.5 samples were collected in the indoor environments of four hospitals and their adjacent outdoor environments in Guangzhou, China during the summertime. The concentrations of 18 target elements in particles were also quantified. The results showed that indoor PM2.5 levels with an average of 99 microg m(-3) were significantly higher than outdoor PM2.5 standard of 65 microg m(-3) recommended by USEPA [United States Environmental Protection Agency. Office of Air and Radiation, Office of Air Quality Planning and Standards, Fact Sheet. EPA's Revised Particulate Matter Standards, 17, July 1997] and PM2.5 constituted a large fraction of indoor respirable particles (PM10) by an average of 78% in four hospitals. High correlation between PM2.5 and PM10 (R(2) of 0.87 for indoors and 0.90 for outdoors) suggested that PM2.5 and PM10 came from similar particulate emission sources. The indoor particulate levels were correlated with the corresponding outdoors (R(2) of 0.78 for PM2.5 and 0.67 for PM10), demonstrating that outdoor infiltration could lead to direct transportation into indoors. In addition to outdoor infiltration, human activities and ventilation types could also influence indoor particulate levels in four hospitals. Total target elements accounted for 3.18-5.56% of PM2.5 and 4.38-9.20% of PM10 by mass, respectively. Na, Al, Ca, Fe, Mg, Mn and Ti were found in the coarse particles, while K, V, Cr, Ni, Cu, Zn, Cd, Sn, Pb, As and Se existed more in the fine particles. The average indoor concentrations of total elements were lower than those measured outdoors, suggesting that indoor elements originated mainly from outdoor emission sources. Enrichment factors (EF) for trace element were calculated to show that elements of anthropogenic origins (Zn, Pb, As, Se, V, Ni, Cu and Cd) were highly enriched with respect to crustal composition (Al, Fe, Ca, Ti and Mn). Factor analysis was used to identify possible pollution source-types, namely street dust, road traffic and combustion processes.

Wintertime indoor air levels of PM10, PM2.5 and PM1 at public places and their contributions to TSP

From 26 October 2002 to 8 March 2003, particulate matter (PM) concentrations (total suspended particles [TSP], PM10, PM2.5 and PM1) were measured at 49 public places representing different environments in the urban area of Beijing. The objectives of this study were (1) to characterize the indoor PM concentrations in public places, (2) to evaluate the potential indoor sources and (3) to investigate the contribution of PM10 to TSP and the contributions of PM2.5 and PM1 to PM10. Additionally, The indoor and outdoor particle concentrations in the same type of indoor environment were employed to investigate the I/O level, and comparison was made between I/O levels in different types of indoor environment. Construction activities and traffic condition were the major outdoor sources to influence the indoor particle levels. The contribution of PM10 to TSP was even up to 68.8%, while the contributions of PM2.5 and PM1 to PM10 were not as much as that of PM10 to TSP.

Fine particles of widely different composition have an adjuvant effect on the production of allergen-specific antibodies

Diesel exhaust particles (DEP) are reported to increase the specific IgE response to allergens, and results from our laboratory suggest that the particle core of DEP contribute to this adjuvant activity. The purpose of the present study was to explore further the adjuvant effect of particles per se, that is particles by themselves. NIH/Ola mice were given two intraperitoneal injections with ovalbumin (OVA; 10 microg) alone or OVA in combination with PSP, polytetrafluoroethylene (teflon), titanium dioxide (TiO(2)) or amorphous silica particles (2.8x10(10)-2.8x10(12)). Blood samples were drawn 7 days after the last injection, and serum levels of allergen-specific and total IgE and IgG2a were measured. All types of particles gave increased levels of allergen-specific IgE and IgG2a. Similar results were obtained after intranasal or intratracheal instillation with OVA plus PSP or silica. Our results indicate that fine particles of widely different composition may have an adjuvant effect on the production of allergen-specific antibodies.

Suspended particulate matter in indoor air: adjuvants and allergen carriers

The overall purpose of this study was to investigate how airborne house dust particles may contribute to an allergic immune response, and thereby also to asthma and other respiratory symptoms. The following aims were set: first, to quantify and characterize indoor suspended particulate matter (SPM) with regard to amount, as well as elemental and size distribution, second, to identify possible mechanisms by which SPM may affect the allergic immune response. A vast majority of the particles in SPM samples from homes in Oslo were found to be less than 2.5 microm in diameter. This PM(2.5) fraction contained, in addition to a large amount of sulfur aerosols and silicates, a lot of soot particles. Most of these were less than 1 microm in diameter. Using an immunogold labeling technique, we found that these soot particles carried cat, dog and birch allergens on their surface. These results show that indoor SPM contains a lot of potential allergen carriers, i.e. soot particles (carbon aggregates), most of them less that 1 microm in diameter and therefore able to transport allergens deep into the respiratory tree. We further found that diesel exhaust particles (DEP), which is likely the main soot component of SPM, adsorbed several well-known allergens in vitro. Furthermore, SPM was found to elicit a local lymph node inflammatory response, and to have an adjuvant activity on the production of IgE antibodies to ovalbumin (OA).

Adjuvant activity of particulate pollutants in different mouse models

Particulate air pollutants may play a role in the increasing prevalence of respiratory allergy by acting as adjuvants for a T helper 2 (Th2) mediated immune response to common allergens. The immunomodulating capacity of well-defined polystyrene particles as well as different particles as present in our environment (diesel exhaust, carbon black, and silica particles) was investigated in different models. Polystyrene particles were injected intraperitoneally or installed intratracheally, while the environmentally relevant particles were injected subcutaneously. From these studies, it becomes clear that all particles exert an adjuvant effect on the immune response to the co-administered antigen. The particle core rather than attached chemical factors seems to be mainly responsible for this effect. The different particles, however, stimulate different types of immune responses, indicating that physicochemical properties of particles may be of importance in steering the response towards a T helper 1 (Th1) or a Th2-like response.

Airborne house dust elicits a local lymph node reaction and has an adjuvant effect on specific IgE production in the mouse

Indoor suspended particulate matter (SPM) consists of many different types of particles, the vast majority of which are less than 2.5 microm in diameter. An important question is how these particles, being inhalable, contribute to asthma and respiratory symptoms. One possibility is that these particles have an adjuvant effect on the immune response and increase the IgE production, or cause a non-specific irritation in the airways, contributing to bronchial hyper-responsiveness. In this study, the adjuvant activity of indoor SPM on the response to the model allergen ovalbumin (OA) in BALB/c mice was investigated, using the popliteal lymph node (PLN) assay. The adjuvant activity on the local lymph node response was determined by measuring the PLN weight, cell numbers and cell proliferation, and the adjuvant activity on the IgE production by measuring the levels of serum IgE specific to OA. SPM was found to give a significant PLN response, both when injected alone and together with OA. SPM was also found to enhance the production of specific IgE to OA when injected together with OA, after reinjection with OA, compared with immunisation with OA alone.

Airborne house dust particles and diesel exhaust particles as allergen carriers

BACKGROUND

Indoor suspended particulate matter (SPM) consists of many different types of particles, the vast majority of which are less than 2.5 microm in diameter. The question arises how these particles may contribute to asthma and respiratory symptoms. One possibility is that airborne dust particles act as carriers of allergens into the airways, as several allergens have been found to be associated with inhalable airborne dust particles.

OBJECTIVE

We studied the presence of three different allergens on the surface of SPM, i.e. Can f 1 (dog), Bet v 1 (birch pollen) and Der p 1 (house dust mite). We also examined the ability of diesel exhaust particulates (DEP) to attach these allergens and Fel d I (cat) in vitro.

METHODS

SPM was collected on polycarbonate filters and an immunogold labelling technique was used to detect the allergens on the particles. The specimens were examined in the backscatter mode of a scanning electron microscope. The same technique was used to examine the binding of the allergens to DEP, after exposing DEP to either crude allergen extracts or partly purified allergens.

RESULTS

Both Can f 1 and Bet v 1 allergens were detected on the surface of the soot particles in SPM mixtures, although to a lesser degree than previously found with Fel d 1. Der p 1 (house dust mite), however, did not show any significant binding to SPM particles. Furthermore, DEP had the ability to adsorb all four allergens in vitro, although to a varying extent.

CONCLUSION

Soot particles in airborne house dust may act as carriers of several allergens in indoor air. Furthermore, DEP has the ability to bind all the four allergens investigated under aqueous conditions in vitro.