In this study we examined 6080 data gathered by our research group during more than 20 years of research on the moss biomonitoring technique, in order to quantify the variability generated by different aspects of the protocol and to calculate the overall measurement uncertainty associated with the technique. The median variance of the concentrations of different pollutants measured in moss tissues attributed to the different methodological aspects was high, reaching values of 2851 (ng·g⁻¹)² for Cd (sample treatment), 35.1 (μg·g⁻¹)² for Cu (sample treatment), 861.7 (ng·g⁻¹)² and for Hg (material selection). These variances correspond to standard deviations that constitute 67, 126 and 59% the regional background levels of these elements in the study region. The overall measurement uncertainty associated with the worst experimental protocol (5 subsamples, refrigerated, washed, 5 × 5 m size of the sampling area and once a year sampling) was between 2 and 6 times higher than that associated with the optimal protocol (30 subsamples, dried, unwashed, 20 × 20 m size of the sampling area and once a week sampling), and between 1.5 and 7 times higher than that associated with the standardized protocol (30 subsamples and once a year sampling). The overall measurement uncertainty associated with the standardized protocol could generate variations of between 14 and 47% in the regional background levels of Cd, Cu, Hg, Pb and Zn in the study area and much higher levels of variation in polluted sampling sites. We demonstrated that although the overall measurement uncertainty of the technique is still high, it can be reduced by using already well defined aspects of the protocol. Further standardization of the protocol together with application of the information on the overall measurement uncertainty would improve the reliability and comparability of the results of different biomonitoring studies, thus extending use of the technique beyond the context of scientific research.

Six hindered phenolic antioxidants (HPAs) from emissions of light-duty diesel and gasoline vehicles were determined. Vehicles were tested on a dynamometer that conducted a typical city-driving protocol and their exhaust samples were collected on filters. A high-performance liquid chromatography coupled with tandem mass spectrometry (HPLC-MS/MS) method was developed for the determination of HPAs in the exhaust samples. Method detection limits reached low ng/m3 in exhaust after optimization of experimental conditions. Identification and quantification were proven to be reliable for these phenols in lightly-loaded and ambient filter samples. In heavily loaded samples, matrix interferences existed, which decreased recoveries of surrogate in both filter and disk. However, matrix spike samples showed good recoveries of target HPAs. In vehicle emission samples, the highest level of HPAs was 2,6-di-tert-butylphenol at 52.7 ng/m3 (28.9 pg/mm2 on filter) in emission of a 2009 Volkswagen Jetta with a diesel engine. Most HPAs were not detected or near detection limits. Therefore, the additives of phenol antioxidants in fuels were mostly oxidized during the combustion process. Further, the 2009 diesel Jetta produced about 7 times more of HPAs than the 2008 Pontiac G5 with a gasoline engine. In addition, it is discovered that engines operated at a colder ambient temperature (−7 °C) yielded more HPA emissions than at the warmer condition (25 °C), because the combustion efficiency of engines are normally reduced at a lower temperature.

Thermal–optical analysis is one of the most widely–recognized methods for measuring organic carbon (OC) and elemental carbon (EC) in atmospheric particulates. Up to date however, there is no standard protocol of analysis and different protocols give varying OC/EC apportionments. This study aims to find an optimal thermal–optical analysis protocol for Philippine OC/EC samples by comparing three widely–used protocols: NIOSH, IMPROVE_A and EUSAAR_2. Philippines is particularly interesting because it has one of the highest EC concentration and lowest OC/EC ratio in the region. In terms of total OC and EC quantification, NIOSH and IMPROVE_A show negative and positive EC bias, respectively – NIOSH exhibits premature EC evolution in the OC4 pure He phase, while IMPROVE_A OC4 temperature step (580 °C) is not sufficiently high, causing some OC to be carried over to He/O2 phase to be measured mainly as EC2. EUSAAR_2 minimizes both effects and may be most accurate in this aspect. However, IMPROVE_A is the only method that is capable of properly resolving individual OC and Philippines’s particularly abundant EC fractions owing to the protocol’s variable step durations. Concurrently, IMPROVE_A and EUSAAR_2 yield lowest pyrolized carbon (PC) formation for urban and rural site, respectively. Minimal PC formation is desired to minimize errors associated with its correction. Finally, transmittance laser correction is preferred over reflectance as it is capable of accounting for char formed within filter. The study thus recommends a modified IMPROVE_A, with increased OC4 temperature step (650 °C, adopted from EUSAAR_2) and transmittance laser correction, as optimal. This protocol is expected to give proper OC and EC evolution, fractionation, and measurement with minimized PC formation and proper correction, leading to more accurate results. Preliminary testing shows that recommended protocol meets those expectations. Application to larger number and wider variety of samples is needed to more properly assert these findings.

Fungal growth within the structure of buildings or in ventilation filters generates “hidden contamination”, which cannot be detected only through visual inspection. At the beginning of development, the fungi release fungal volatile organic compounds (FVOCs) into the atmosphere, which can originate from metabolic pathways or from the enzymatic degradation of materials. This study analyzed the air quality of a public referral hospital in Fortaleza, Ceará, Brazil in terms of FVOCs, to establish ways to improve methods of monitoring and control of specific sectors in the hospital. For that, we created and validated a protocol for detection of FVOCs, using GC/MS, while fungal samples were identified by analysis of macro and micromorphology. In total, 48 samples (60.5% positive) were analyzed for FVOCs; 7 were detected in at least one of the sectors analyzed, with 2-heptanone (179.5 μg/m3) and 2-methyl-1-propanol (121.5 μg/m3) as the most abundant. With respect to fungal findings, 24 samples were analyzed, with a high number of colony-forming units per cubic meter (CFU/m3) observed in all sectors. The airborne fungal spectrum revealed the existence of 19 genera, composed predominantly by hyaline filamentous deuteromycetes. Analysis with periodic monitoring is still needed to allow improvement in the data quality. Also, further discussion on the subject in the academic and legislative environment is needed to contribute to the systematic study of aerobiology.

Concentrations of organic carbon (OC) and elemental carbon (EC) in PM2.5 were measured at an urban (Valenzuela City, Metro Manila) and a rural (Angat, Bulacan) site in the Philippines from September 2011 to August 2012 by thermal–optical reflectance analysis following IMPROVE–A protocol. Results show that OC (8.00μg m−3) and EC (6.63μg m−3) levels in Valenzuela were 2–3 times higher than those in Angat (OC: 4.08μg m−3, EC: 2.29μg m−3). The total carbon contributions (OC+EC) to PM2.5 mass for the urban and rural site were 38.9% and 19.7% respectively. Compared to neighboring countries in Asia, the Philippine sites have intermediate OC concentrations and greatly elevated EC levels. These suggest the presence of highly inefficient combustion sources and highlight the need for the regulation of such emissions. Valenzuela was dominated by OC2, OC3, and EC1 (carbon fractions evolving at 280°C and 480°C in pure He phase and 580°C in He/O2 phase of the analysis, respectively) which points to vehicular, industrial, and cooking sectors as the possible main sources. While generally having lower concentrations and being less EC–dominated, Angat had remarkably higher levels of the EC2 fraction which suggests a unique EC source in the area. Conditional Probability Function (CPF) for Valenzuela OC and EC show similar results pointing towards the 30°, 150°, and 210° direction, indicating common sources for these species. Detailed survey of the surrounding area is needed to ascertain the identities of the sources present in these directions.

Large measurement networks of Black Carbon (BC) aerosol are important for understanding its impacts on climate and health. PM2.5 filter samples were collected at three urban US locations and one India urban location and were analyzed for Elemental Carbon (EC) and Organic Carbon (OC) concentrations using thermo-optical analysis (TO) following the IMPROVE protocol for US samples and NIOSH protocol for India samples. Site and season-specific calibrations of an inexpensive photo-reference (PR) method were created with TO EC measurements of the US filter samples whereas method-specific calibration was prepared using India filter samples. Piece-wise calibration based on filter loading was also explored. Calibrations were applied across different sites, seasons and methods to determine Root Mean Square Error (RMSE) and average absolute error in each calibration by comparing with reference EC measurements. This paper investigates various calibrations of PR method to improve the agreement between PR method and TO EC measurements. Difference in BC estimated error remained within ±10% among three urban US site-specific calibrations, which suggests that site-specific calibrations are not necessary. Season based calibrations were found to perform best (least RMSE/Mean EC), when applied to same season test samples but resulted in large errors of up to 60% RMSE/Mean EC when applied to different seasons, thus warranting the use of season-specific calibrations of the PR method. RMSE relative to mean EC was 50% when calibration prepared from US samples (IMPROVE protocol) was used to test India samples (NIOSH protocol). However, method-specific calibration prepared from India samples reduced the error to 24%, showing the large dependency of PR method on reference BC measurement method. Calibration based on filter loading reduced the RMSE slightly for both US urban and India samples and indicated that filters with loadings higher than 20 μg cm−2 are not suitable for estimating BC by PR method.

Semi–volatile polycyclic aromatic hydrocarbons (PAHs) and their oxygenated analogues (OPAHs) are associated with adverse health effects. They are normally sampled by active sampling but recently a number of passive samplers that rely on calibrated sampling rates (Rs), have successfully captured the full suite of PAHs associated with both the gas–and particulate phases. However, there have been few studies on the mechanisms controlling particle deposition during passive sampling. To address this issue, a diesel exhaust aerosol with a number mode of ~120 nm containing PAHs and OPAHs that are partitioned approximately equally between the gas and particle phases was used to study the performance of a passive sampler design of axial badge type. The sampler was tested with two different collection substrates and the diffusion distance was varied to determine its effects on sample collection. The results obtained were compared to data gathered by active sampling of the gas and particle phases. In addition, Rs values were calculated for selected PAHs and OPAHs. The material collected by the passive samplers was analyzed using a highly sensitive protocol involving thermal desorption followed by GC–MS. The passive sampler yielded highly reproducible Rs values and its PAH uptake was shown to be enhanced by using a collection substrate modified with a gas–adsorbing coating (Tenax®) which was exclusively addressed being uptake from the gaseous phase. However, the uptake of the less volatile OPAHs was not affected by the use of a coated substrate. Experimental data and theoretical calculations showed that particle diffusion may have substantially less impact on particulate matter collection than other deposition mechanisms. The high sensitivity and small size of the sampler suggest that after testing in other environments it may have diverse applications in sampling campaigns and as a promising candidate for a personal sampler.