Aromatic Hydrocarbons In Ambient Air Research Articles

Atmospheric polycyclic aromatic hydrocarbons in India: geographical distribution, sources and associated health risk-a review.

Atmospheric distribution of polycyclic aromatic hydrocarbons and associated human health risks have been studied in India. However, a comprehensive overview is not available in India, this review highlights the possible sources, and associated cancer risks in people living in different zones of India. Different databases were searched for the scientific literature on polycyclic aromatic hydrocarbons in ambient air in India. Database searches have revealed a total of 55 studies conducted at 139 locations in India in the last 14years between 1996 and 2018. Based on varying climatic conditions in India, the available data was analysed and distributed with four zone including north, east, west/central and south zones. Comparatively higher concentrations were reported for locations in north zone, than east, west/central and south zones. The average concentrations of ∑PAHs is lower in east zone, and concentrations in north, west/central and south zones are higher by 1.67, 1.47, and 1.12 folds respectively than those in east zone. Certain molecular diagnostic ratios and correlation receptor models were used for identification of possible sources, which aided to the conclusion that both pyrogenic and petrogenic activities are the mixed sources of PAH emissions to the Indian environment. Benzo(a)pyrene toxicity equivalency for different zones is estimated and presented. Estimated Chronic daily intake (CDI) due to inhalation of PAHs and subsequently, cancer risk (CR) is found to be ranging from extremely low to low in various geographical zones of India.

Methodical approaches to the detection polycyclic aromatic hydrocarbons in ambient air (analytical review)

Among the persistent organic pollutants of atmospheric air, a special place is occupied by a group of polycyclic aromatic hydrocarbons (PAHs) or polyarenes due to their high carcinogenic hazard. In view of the ubiquitous presence of these substances in the atmospheric air, low values of hygienic standards and values of reference concentrations (RfC) for chronic inhalation exposure, the qualitative and quantitative identification of PAHs is the critical task. Purpose is to analyze modern methodological approaches used in laboratory practice to determine polyarenes in atmospheric air on the base of Russian and foreign sources. The paper considers modern methods for the analytical control of PAHs in atmospheric air, officially approved in the Russian Federation and presented in the world literature. The search for literary sources was carried out using the PubMed, RSC Publishing, Springer Nature, SCOPUS, eLIBRARY.RU databases. An analysis of the methodological and scientific and technical literature on methods for the determination of PAHs in atmospheric air made it possible to identify the main directions of methodological developments used in modern laboratory practice for the analytical control of polyarenes in air. The advantages and disadvantages of specific methods, individual stages of analysis, conditions for sampling, storage and transportation of samples, which together can lead to false positive or false negative results, are presented. Conclusion. Modern methods for the analysis of polyarenes in atmospheric air are the result of continuous improvement in the technique of performing individual analytical procedures, the development of new methodological approaches to solving analytical problems, the emergence of new, more advanced measuring and auxiliary equipment, which makes it possible to develop highly sensitive and highly selective methods for measuring toxicants in the human environment at the level of MPCdaily average, MPCone-time and RfC for chronic inhalation exposure.

Determination of particulate polycyclic aromatic hydrocarbons in ambient air by gas chromatography-mass spectrometry after molecularly imprinted polymer extraction

A solid phase extraction procedure (SPE) is described for the quantitative analysis of polycyclic aromatic hydrocarbons (PAHs) in atmospheric particulate matter (PM), as ubiquitous environmental pollutants routinely measured in air quality monitoring. A SPE cartridge was used based on a molecular imprinted polymer (MIP-SPE) properly tailored for selective retention of PAHs with 4 and more benzene fused rings. The performance of the clean-up procedure was evaluated with the specific concern of selective purification towards saturated hydrocarbons, which are the PM components mostly interfering GC analysis of target PAHs. Under optimized operative conditions, the MIP-SPE provided analyte recovery close to 95% for heavier PAHs, from benzo(α)pyrene to benzo(ghi)perylene, and close to 90% for four benzene rings PAHs, with good reproducibility (RSDs: 2.5%-5.9%). Otherwise, C17-C32n-alkanes were nearly completely removed. The proposed method was critically compared with Solid Phase Micro Extraction (SPME) using a polyacrylate fiber. Both methods were successfully applied to the analysis of ambient PM2.5 samples collected at an urban polluted site. Between the two procedures, the MIP-SPE provided the highest recovery (R% ≥ 93%) for PAHs with 5 and more benzene rings, but lower for lighter PAHs. In contrast, SPME showed a mean acceptable R% value (∼ 80%) for all the investigated PAHs, except for the heaviest PAHs in the most polluted samples (R%: 110%-138%), suggesting an incomplete purification from the interfering n-hydrocarbons.

Characteristics of polycyclic aromatic hydrocarbons in ambient air of a tropical mega-area, Ho Chi Minh City, Vietnam: concentration, distribution, gas/particle partitioning, potential sources and cancer risk assessment.

This is the first investigation on overall characteristics of 25 polycyclic aromatic hydrocarbons (PAHs) (15 PAHs regulated by US-EPA (excluding naphthalene) and 16 PAHs recommended by the European Union) in ambient air of Ho Chi Minh City, Vietnam. Their levels, congener profiles, gas/particle partitioning, potential sources of atmospheric PAHs (gas and particulate phases), and lung cancer risks in the dry and rainy seasons were examined. The ∑25 PAH concentration in the dry and rainy seasons ranged from 8.79 to 33.2ngm-3 and 26.0 to 60.0ngm-3, respectively. Phenanthrene and Indeno[123-cd]pyrene were major contributors to gaseous and particulate PAHs, respectively, while benzo[c]fluorene was dominant component of the total BaP-TEQ. The ∑16 EU-PAH concentration contributed to 13 ± 2.7% of the total ∑ 25 PAH concentration; however, they composed over 99% of the total ∑ 25 PAH toxic concentration. Adsorption mainly governed the phase partitioning of PAHs because the slope of correlation between logKp and logP0L was steeper than - 1. Vehicular emission was the primary source of PAHs in two seasons; however, PAHs in the dry season were also originated from biomass burning. Assessment of lung cancer risk showed that children possibly exposed to potential lung cancer risk via inhalation.

Chlorinated and brominated polycyclic aromatic hydrocarbons in ambient air: seasonal variation, profiles, potential sources, and size distribution

Chlorinated and brominated polycyclic aromatic hydrocarbons (ClPAHs and BrPAHs, respectively) are a new derivative group of PAHs. These halogenated PAHs (Halo-PAHs) have been reported to be carcinogenic and are considered emerging persistent organic pollutants. Gaining a clear understanding of the distribution and behavior of these ubiquitous organic pollutants is essential for the control and mitigation of their emission into the environment. However, research into the characteristics of Halo-PAHs in the atmosphere has been somewhat limited. This review paper thus aims to provide an overview of the seasonal patterns, profiles, potential sources, and particle-size distributions of atmospheric ClPAHs and BrPAHs with 3–5 rings. Most previous studies have focused on particulate Halo-PAHs and reported that their levels are higher during the cold season than during the warm season, with this seasonal variation more apparent for ClPAHs than for BrPAHs. In terms of their phase distribution, ClPAHs and BrPAHs share a similar trend, with their gaseous concentrations highest in summer and lowest in winter and their particulate concentrations exhibiting the opposite trend. Halo-PAH profiles have been shown to differ between sampling locations, possibly reflecting differences in the potential sources present at these sites, e.g., coal burning, traffic emissions, and industrial activity. The majority of Halo-PAHs tend to accumulate as ultrafine particles with an aerodynamic diameter of less than 1.0 µm. Overall, a detailed understanding of the characteristics of Halo-PAHs in the atmosphere has yet to be achieved; hence, further research on atmospheric Halo-PAHs is necessary.

Oxygenated and Nitrated Polycyclic Aromatic Hydrocarbons in Ambient Air-Levels, Phase Partitioning, Mass Size Distributions, and Inhalation Bioaccessibility.

Among the nitrated and oxygenated polycyclic aromatic hydrocarbons (NPAHs and OPAHs) are some of the most hazardous substances to public health, mainly because of their carcinogenicity and oxidative potential. Despite these concerns, the concentrations and fate of NPAHs and OPAHs in the atmospheric environment are largely unknown. Ambient air concentrations of 18 NPAHs, 5 quinones, and 5 other OPAHs were determined at two urban and one regional background sites in central Europe. At one of the urban sites, the total (gas and particulate) concentrations of Σ10OPAHs were 10.0 ± 9.2 ng/m3 in winter and 3.5 ± 1.6 ng/m3 in summer. The gradient to the regional background site exceeded 1 order of magnitude. Σ18NPAH concentrations were typically 1 order of magnitude lower than OPAHs. Among OPAHs, 9-fluorenone and (9,10)-anthraquinone were the most abundant species, accompanied by benzanthrone in winter. (9,10)-Anthraquinone represented two-thirds of quinones. We found that a large fraction of the target substance particulate mass was carried by submicrometer particles. The derived inhalation bioaccessibility in the PM10 size fraction is found to be ≈5% of the total ambient concentration of OPAHs and up to ≈2% for NPAHs. For 9-fluorenone and (9,10)-anthraquinone, up to 86 and 18%, respectively, were found at the rural site. Our results indicate that water solubility could function as a limiting factor for bioaccessibility of inhaled particulate NPAHs and OPAHs, without considerable effect of surfactant lipids and proteins in the lung lining fluid.

Utilization of activated carbon as an effective replacement for a commercialized three-bed sorbent (Carbopack) to quantitate aromatic hydrocarbons in ambient air

The potential use of activated carbon (AC) as an inexpensive and effective alternative sorbent material in thermal desorption is presented and validated for the analysis of aromatic volatile organic compounds (VOCs) such as benzene, toluene, m-xylene, and styrene (BTXS) in air. The optimum desorption conditions of an AC sampling tube (2 mg AC bed) were determined and compared with a commercial three-bed (Carbopack; C + B + X) tube sampler as a reference. The AC sampler exhibited good linearity (R2 > 0.99) and reproducibility (RSE of 2.38 ± 0.21%) for BTXS analysis. The AC tube sampler showed good storability (up to 3 d) and excellent recyclability (up to 50 cycles). An analysis of BTXS in ambient air showed excellent agreement between AC and CBX (bias < 5%). The 1% breakthrough volume values for 2 mg AC, when tested at 100 ppb of benzene as a sole component or in a BTXS mixture, were 10,000 or 5000 L g−1, respectively. The results of this study support the performance of AC as a suitable medium for sampling VOCs as reliable as high-cost commercial sorbent products.

Gas–particle partition and spatial characteristics of polycyclic aromatic hydrocarbons in ambient air of a prototype coking plant

This study investigated the gas–particle partition and spatial characteristics of polycyclic aromatic hydrocarbons (PAHs) in the ambient air of a prototype coking plant. High-volume samplers with glass fiber filters (GFFs) and polyurethane foams (PUFs) were used to collect PAHs in both gaseous and particulate phases. The EPA's 16 priority-controlled PAHs were measured using gas chromatography equipped with a mass-selective detector (GC-MS). The total PAH concentrations ranged from 1.32 μg m−3 to 9.41 μg m−3, with an average of 4.20 μg m−3. PAH abundance at the various sites of the coking plant was determined to be in the following order: coke side > machine side > leeward site; the lowest values were at the reference site and factory boundary. The medium-molecular-weight PAHs had the highest fraction at the coke side, whereas the low-molecular-weight PAHs were predominant at other sampling sites. Considerable amount of chrysene was detected at the coke side, fluorene at the machine side, acenaphthene at the leeward site (240 m downwind of the coke oven), and naphthalene at the other three sites. The gaseous fractions of PAHs at the six sampling sites ranged from 46.3% to 85.8% of the total PAHs in the gas–particle systems; and gaseous PAHs were predominant in the ambient air of the coking plant—except for the coke side, where the PAHs were dominantly partitioned to the particles. In addition, the particulate benzo(a)pyrene equivalence (BaPeq) fraction was high in the coking plant air. The slope (mr) values ranged from −0.59 to −0.39 in the plant, indicating that the absorption mechanism, rather than the adsorption mechanism, dominated the gas–particle partitioning. The intercept (br) values carry the information on the gaseous–particulate phase distribution of semivolatile organic compounds when the mr values are similar. The organic matter fraction in particles, particulate phase fraction of PAHs, and toxicity of particulate matter were found to increase with an increase in br values at similar mr values. The predominant mechanism was absorption for dibenz(a,h)anthracene, benzo(ghi)perylene, and indeno(1,2,3-cd)pyrene, but adsorption for benzo(b)fluoranthene, benzo(a)pyrene, and benzo(k)fluoranthene at the coke and machine sides. By contrast, for most high-molecular-weight PAHs, absorption into the organic matter was the predominant mechanism at other sites. The gas–particle partitioning mechanism of individual PAHs was closely related to the distance from the coke oven, rather than the orientation to the oven. These results may be of great importance in understanding the pollutant process and atmospheric transport of PAHs and may provide guidance to decision makers regarding air pollution control.

Characterization of PM2.5-bound nitrated and oxygenated polycyclic aromatic hydrocarbons in ambient air of Langfang during periods with and without traffic restriction

PM2.5-bound nitrated polycyclic aromatic hydrocarbons (nPAHs) and oxygenated polycyclic aromatic hydrocarbons (oPAHs) in ambient air were analysed in Langfang during periods with and without traffic restriction. During traffic restriction periods, 20% of gasoline vehicles and all diesel vehicles were restricted to travel within downtown. The 2-nitrofluoranthene/1-nitropyrene ratios obtained during the sampling periods implied that direct emission, especially from diesel vehicles, is the main source for the nPAHs in Langfang. The primary sources of nPAHs and oPAHs, including diesel vehicle emissions and gasoline vehicle emissions, were reduced in the P2 period. Thus, the concentrations of 1-nitropyrene, 3-nitrobenzanthrone, 9-nitrophenanthrene, 2-nitrofluorene, 7-nitrobenz[a]anthracene, 9,10-anthraquinone and benzanthrone were reduced up to 73.3% under this traffic restriction policy. However, the concentrations of 2-nitrofluoranthene and 9-fluorenone formed from gas phase reactions increased slightly. Meanwhile, the chemical profiles of nPAHs and oPAHs changed with traffic fleet variation, and cancer risk levels decreased under the traffic restriction policy. Hence, the traffic restriction policy did effect the ambient concentrations of nPAHs and oPAHs.

Optimization and Validation of Thermal Desorption Gas Chromatography-Mass Spectrometry for the Determination of Polycyclic Aromatic Hydrocarbons in Ambient Air.

Thermal desorption (TD) coupled with gas chromatography/mass spectrometry (TD-GC/MS) is a simple alternative that overcomes the main drawbacks of the solvent extraction-based method: long extraction times, high sample manipulation, and large amounts of solvent waste. This work describes the optimization of TD-GC/MS for the measurement of airborne polycyclic aromatic hydrocarbons (PAHs) in particulate phase. The performance of the method was tested by Standard Reference Material (SRM) 1649b urban dust and compared with the conventional method (Soxhlet extraction-GC/MS), showing a better recovery (mean of 97%), precision (mean of 12%), and accuracy (±25%) for the determination of 14 EPA PAHs. Furthermore, other 15 nonpriority PAHs were identified and quantified using their relative response factors (RRFs). Finally, the proposed method was successfully applied for the quantification of PAHs in real 8 h-samples (PM10), demonstrating its capability for determination of these compounds in short-term monitoring.

Characterization of PM2.5-Bound Polycyclic Aromatic Hydrocarbons in the Ambient Air of Győr, Hungary

ABSTRACTIn Hungary, the nationwide monitoring of PM10-bound polycyclic aromatic hydrocarbons (PAHs) in ambient air is great importance for a number of reasons related to human health, the environment and compliance with European Union legislation. However, the measurement of PAH concentrations in PM2.5 aerosol fraction has not been carried out. Therefore, the concentration, distribution and sources of PM2.5-bound PAHs at different urban sites of Győr were investigated in a heating season. The total PAH concentrations (sum of 19 individual PAH compounds) ranged from 1.32 to 37.27 ng/m3 with the mean value of 10.54 ng/m3. The high molecular weight PAHs with 5 and 6 aromatic rings were the most abundant PAHs in PM2.5 aerosol samples, which averaged 82% of total PAHs. Using benzo(a)pyrene (BaP) equivalent approach on the concentration data of carcinogenic PAH species, BaP and indeno(1,2,3-cd)pyrene contributed the highest carcinogenic exposure equivalent (1.25 and 0.19 ng/m3 on average). However, the incremental lifetime cancer risk (ILCR) values for resident children and adults indicated low-potential cancer risk (ILCR < 10−6). The source apportionment results reflected that the major sources of PAH compounds in the Győr atmosphere were fossil fuel combustion and vehicle emissions.

Emission sources and health risk assessment of polycyclic aromatic hydrocarbons in ambient air during heating and non-heating periods in the city of Novi Sad, Serbia

The paper presents the assessment of emission sources and health risk of 16 PAHs in the city of Novi Sad, Serbia, with developed oil, food, chemical and cement industry. Although the observed region has been previously studied with regard to the occurrence of PAHs in ambient air, the sources of emission and health risk using multivariate statistical methods have never been studied before. The research was conducted during the heating and non-heating periods at three sampling sites located in industrial, residential and high-traffic area. The samples were collected by high-volume air sampler and analysed using the GC/MS system. The data were processed using the positive matrix factorization (PMF) and cluster analysis. To assess the cancer-risk of PAHs, potency equivalency factor approach was used. The results of PMF analysis have indicated that significant sources of PAH emissions are industrial processes and diesel combustion during the non-heating, and coal combustion, heating plants and diesel combustion during the heating season. Cluster analysis of experimental data has confirmed the results obtained using the PMF method. Estimated values of lifetime lung cancer risk were higher than those set by the World Health Organization and US Environmental Protection Agency which indicates that cancer risk due to exposure to PAHs in ambient air exists in both time periods on the territory of Novi Sad.

Polycyclic aromatic hydrocarbons in ambient air, surface soil and wheat grain near a large steel-smelting manufacturer in northern China

The total concentrations and component profiles of polycyclic aromatic hydrocarbons (PAHs) in ambient air, surface soil and wheat grain collected from wheat fields near a large steel-smelting manufacturer in Northern China were determined. Based on the specific isomeric ratios of paired species in ambient air, principle component analysis and multivariate linear regression, the main emission source of local PAHs was identified as a mixture of industrial and domestic coal combustion, biomass burning and traffic exhaust. The total organic carbon (TOC) fraction was considerably correlated with the total and individual PAH concentrations in surface soil. The total concentrations of PAHs in wheat grain were relatively low, with dominant low molecular weight constituents, and the compositional profile was more similar to that in ambient air than in topsoil. Combined with more significant results from partial correlation and linear regression models, the contribution from air PAHs to grain PAHs may be greater than that from soil PAHs.

Variations of polycyclic aromatic hydrocarbons in ambient air during haze and non-haze episodes in warm seasons in Hangzhou, China

To investigate the characteristics of polycyclic aromatic hydrocarbons (PAHs) during haze episodes in warm seasons, daily PM2.5 and gaseous samples were collected from March to September 2015 in Hangzhou, China. Daily samples were further divided into four groups by the definition of haze according to visibility and relative humidity (RH), including non-haze (visibility, >10km), light haze (visibility, 8-10km, RH <90%), medium haze (visibility, 5-8km, RH <90%), and heavy haze (visibility, <5km, RH <90%). Significantly higher concentrations of PM2.5-bound PAHs were found in haze days, but the mean PM2.5-bound PAH concentrations obviously decreased with the aggravation of haze pollution from light to heavy. The gas/particle partitioning coefficients of PAHs decreased from light-haze to heavy-haze episodes, which indicated that PM2.5-bound PAHs were restricted to adhere to the particulate phase with the aggravation of haze pollution. Absorption was considered the main mechanism of gas/particle partitioning of PAHs from gaseous to particulate phase. Analysis of air mass transport indicated that the PM2.5-bound PAH pollution in haze days was largely from regional sources but also significantly affected by long-range air mass transport. The inhalation cancer risk associated with PAHs exceeded the acceptable risk level markedly in both haze and non-haze days.

Measurements and source apportionment of particle-associated polycyclic aromatic hydrocarbons in ambient air in Riyadh, Saudi Arabia

Ambient air samples were obtained in Riyadh, the capital and largest city of Saudi Arabia, during two measurement campaigns spanning September 2011 to September 2012. Sixteen particle-phase polycyclic aromatic hydrocarbons (PAH) were quantified in 167 samples. Pyrene and fluoranthene were the most abundant PAH, with average of 3.37 ± 14.01 ng m−3 and 8.00 ± 44.09 ng m−3, respectively. A dominant contribution from low molecular weight (LMW) PAH (MW < 228) suggested a large influence of industrial emissions on PAH concentrations. Monte Carlo source apportionment using diagnostic ratios showed that 80 ± 10% of the average LMW PAH concentrations were contributed by petroleum vapor emissions, while 53 ± 19% of high molecular weight (HMW) PAH were from solid fuel combustion emissions. The positive matrix factorization model estimated that oil combustion emissions dominated total PAH concentrations, accounting for on average 96%, likely due to widespread use of oil fuels in energy production (power plants and industries). Our results demonstrate the significant influence of petroleum product production and consumption on particulate-phase PAH concentrations in Riyadh, but also point to the importance of traffic and solid fuel burning, including coke burning and seasonal biomass burning, especially as they contribute to the ambient levels of HMW PAH.

Concentrations and origins of nitro-polycyclic aromatic hydrocarbons and oxy-polycyclic aromatic hydrocarbons in ambient air in urban and rural areas in northern China

Twelve nitro-PAHs (nPAHs) and four oxy-PAHs (oPAHs) were measured in air samples for 12 months at 18 sites in urban settings, rural villages, or rural fields in northern China. The nPAH concentrations were higher in urban areas (1.3 ± 1.3 ng/m3), and nPAH/parent PAH ratios were higher (suggesting important contributions from motor vehicles and secondary formation) in urban sites than in rural villages. oPAHs are primarily emitted from solid fuel combustion and motor vehicles, and similar oPAH concentrations were found in urban areas (23 ± 20 ng/m3) and rural villages (29 ± 24 ng/m3). The high numbers of motor vehicles in Beijing and intensive industrial activity in Taiyuan and Dezhou caused higher nPAH concentrations. No spatial trend in oPAH concentrations was found in the rural villages, because similar oPAH mixtures are emitted from solild fuel combustion. The nPAH and oPAH concentrations were higher in the winter, and correlated with residential energy consumption and precipitation.

Levels of persistent organic pollutants and polycyclic aromatic hydrocarbons in ambient air of Central and Eastern Europe

The ambient air and soil monitoring network was established in 22 countries of Central and Eastern Europe (CEE) in support of the Global Monitoring Plan under the Stockholm Convention on Persistent Organic Pollutants. Polyurethane foam based passive air samplers were used as a tool for monitoring of POPs in ambient air at remote, rural, suburban, and urban sites with the aim of filling the information gaps identified in this UN region. High atmospheric levels of PCBs, HCHs, DDTs or HCB were observed at the rural as well as urban sites indicating that organochlorines still pose a significant problem in CEE. Pesticide storage, industrial complexes, military zones, and landfills were responsible for the elevated levels of POPs in this survey. The background levels of these compounds, however, were often elevated, too.

Characterization of Gaseous and Particulate Polycyclic Aromatic Hydrocarbons in Ambient Air of Delhi, India

Three seasonal sampling campaigns were undertaken at an urban site of Delhi for collection of PAHs in particulate and gas phase. Sampling was done by using modified Respirable Dust (PM ≤10μm) sampler attached with polyurethane foam (PUF) plugs and compared with conventional Respirable Dust (PM ≤10 μm) sampler. Total 16 EPA PAH (gaseous + particulate) were determined by Gas Chromatograph-Mass Spectrophotometer (GC-MS). The 3-ring PAH constitutes approximately 90% of the gaseous PAHs with phenanthrene, fluoranthene, acenapthylene, and acenaphthene being the most abundant gaseous PAHs. PAHs with 4- to 6- rings accounted for 92%, 87% and 78% in samples collected during winter, summer and monsoon season respectively. Gaseous PAHs, particulate PAHs and total PAHs were higher during winter as compared to summer and monsoon seasons. The contribution of particulate PAHs were 1.4, 2.1, and 2.5 times higher in winter, summer and monsoon, respectively than of gaseous PAHs. Indeno[123-cd]pyrene, benzo[ghi]perylene, dibenzo[ah]anthracene, benzo[b]fluoranthene, benzo[k]fluoranthene, benzo[a]pyrene and chrysene were found to be the most abundant PAH compounds in the particulate PAHs during all the seasons. The result from application of diagnostic ratio suggests that the higher particulate PAHs emissions were predominantly associated with vehicular emissions along with emissions from biomass burning during winter season.

Particle-phase concentrations of polycyclic aromatic hydrocarbons in ambient air of rural residential areas in southern Germany.

An important source of polycyclic aromatic hydrocarbons (PAHs) in residential areas, particularly in the winter season, is the burning process when wood is used for domestic heating. The target of this study was to investigate the particle-phase PAH composition of ambient samples in order to assess the influence of wood combustion on air quality in residential areas. PM10 samples (particulate matter <10 μm) were collected during two winter seasons at two rural residential areas near Stuttgart in Germany. Samples were extracted using toluene in an ultrasonic bath and subsequently analysed by gas chromatography–mass spectrometry. Twenty-one PAH compounds were detected and quantified. The PAH fingerprints of different wood combustion emissions were found in significant amounts in ambient samples and high correlations between total PAHs and other wood smoke tracers were found, indicating the dominant influence of wood combustion on air quality in residential areas. Carcinogenic PAHs were detected in high concentrations and contributed 49% of the total PAHs in the ambient air. To assess the health risk, we investigated the exposure profile of individual PAHs. The findings suggest that attention should be focused on using the best combustion technology available to reduce emissions from wood-fired heating during the winter in residential areas.

Carbonyl atmospheric reaction products of aromatic hydrocarbons in ambient air

To convert gaseous carbonyls to oximes during sampling, an XAD-4 resin denuder system pre-coated with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine and followed by analysis with methane positive chemical ionization gas chromatography/mass spectrometry was used to measure carbonyls in ambient air samples in Riverside, CA. In conjunction with similar analyses of environmental chamber OH radical-initiated reactions of o- and p-xylene, 1,2,4-trimethylbenzene, ethylbenzene, 4-hydroxy-2-butanone and 1,4-butanediol, we identified benzaldehyde, o-, m- and p-tolualdehyde and acetophenone and the dicarbonyls glyoxal, methylglyoxal, biacetyl, ethylglyoxal, 1,4-butenedial, 3-hexene-2,5-dione, 3-oxo-butanal, 1,4-butanedial and malonaldehyde in the ambient air samples. As discussed, these carbonyls and dicarbonyls can be formed from the OH radical-initiated reactions of aromatic hydrocarbons and other volatile organic compounds emitted into the atmosphere, and we conclude that in situ atmospheric formation is a major source of these carbonyls in our Riverside, CA, ambient air samples.