Control Of Volatile Organic Compounds Research Articles

КОНТРОЛЬ СУММАРНОГО СОДЕРЖАНИЯ ЛЕТУЧИХ ОРГАНИЧЕСКИХ СОЕДИНЕНИЙ В ВОЗДУХЕ НЕПРОИЗВОДСТВЕННЫХ ПОМЕЩЕНИЙ

Обзорная статья посвящена вопросам оценки загрязненности воздуха непроизводственных помещений летучими органическими веществами, многие из которых токсичны и могут представлять серьезную угрозу для здоровья людей. Несмотря на то, что показатель суммарного содержания летучих органических веществ в воздушной среде замкнутых помещений не характеризует однозначно опасность для здоровья человека, нормативы этого показателя введены во многих странах. Дан обзор работ, посвященных методам определения суммарного содержания летучих органических веществ в воздухе непроизводственных помещений. Описаны подходы к измерению этого параметра и их практическая реализация. Отмечен рост использования переносных газоанализаторов для оперативного контроля состояния воздуха в этих условиях. An important issue of keeping control of indoor air pollution caused by volatile organic compounds (VOCs) is reviewed taking into consideration their potential toxicity and a possible threat to human health after long-term exposure. Unlike the established rules for regulating and control of VOCs in the working zone air of industrial enterprises, the air of non-industrial premises has always received much less attention, and the problem of its quality assessment does not appear to have been resolved completely. Despite the fact that a value of total volatile organic compounds of indoor air premises does not unambiguously characterize a human health hazard, the standards for this parameter have been introduced in many countries. Studies devoted to developing methods for determining the total content of volatile organic compounds in indoor air are reviewed. The known and new-coming approaches to measuring this parameter and their implementation are described. An increase in applying portable gas analyzers for on-line monitoring of indoor air characteristics is outlined.

Empirical Development of Ozone Isopleths: Applications to Los Angeles

Understanding quantitative relationships between ambient ozone concentrations and precursor emissions is important to policymakers and stakeholders. Such relationships are often captured as ozone isopleth diagrams developed using air quality models. Model-based approaches have limitations, including errors stemming from uncertainties in inputs and modeled processes, and can be computationally burdensome. We develop and apply an empirical method based on ozone design values calculated in the South Coast Air Basin, California, for 1975–2016 to construct ozone isopleths. The study domain is the area with the highest ozone levels in the United States that has experienced high levels of emissions control. Quadratic and log-quadratic models were constructed, and both capture the actual observations very well (R2 ∼ 0.98) and re-create the general characteristics of traditional air quality model-generated isopleths. The empirical approach benefits from being based on observations that are highly accurate (but have a low spatial coverage). Analysis shows that uncertainties are <30% near likely future control levels. Furthermore, the method shows that the nitrogen oxide (NOx)–volatile organic compound (VOC)–ozone system in the 1970s was in the region where VOC controls were most effective and then more recently moved to the region where both VOC and NOx controls are effective.

VOCs and Odors Control and Development in Pharmaceutical Fermentation Industry

Volatile organic compounds (VOCs) and odors, which pose potential hazards to human health and the ecosystem, are two of the most important pollutants emitted from the pharmaceutical fermentation industry. Currently, basic research on the characteristics of the pollution and effective prevention technology for VOCs and odors emitted from the pharmaceutical fermentation industry are limited. Specifically, the pharmaceutical fermentation industry lacks adequate theoretical guidance on the supervision and control of VOCs and odors, and some companies even face relocations. Using the pharmaceutical fermentation industry as the study object, the pollution characteristics of VOCs and odors emitted from different production workshops, sewage treatment stations, and the disposal of pharmaceutical residues were assessed. Based on the studies above, the progress of research into representative control technologies were also reviewed systematically. For VOCs and odors control in the pharmaceutical fermentation industry, four suggestions for future research were proposed:① The production processes should be optimized, and the discharge of pollution should be reduced throughout the entire processes; ② Basic research should be carried out on the pollution characteristics of the VOCs and odors emitted from the pharmaceutical fermentation industry, and a rapid and effective method to trace the sources of VOCs and odors should be established; ③ A comprehensive evaluation of control technologies should be conducted, taking cost and efficiency into account; ④ Emission standards and technical orders for VOCs and odors in the pharmaceutical fermentation industry should be formulated and implemented immediately.

Ambient volatile organic compound presence in the highly urbanized city: source apportionment and emission position

Ambient volatile organic compounds (VOCs) measured hourly by the photochemical assessment monitoring station (PAMS) in Taichung were collected to analyze characteristics and provide source apportionment of VOCs. In this study, aromatics and alkanes were found to be the major VOC categories. The major species included toluene, m,p-xylene, propane, ethane, n-butane, and isopentane, which came from the east and southeast. VOC concentrations were highest in March and lowest in July, due to temperature, accumulated precipitation, boundary layer effects, and photochemical reactions. Positive matrix factorization analysis showed that industrial emissions (solvent usage and industry) were the major source, which originated from the northwest to south. Traffic emissions (fuel evaporation and vehicular emissions) were the second highest source and came from the southeast. An estimation of ozone formation suggests that industrial emissions were still a key source. Therefore, effective abatement strategies for industrial emissions should be given priority for VOC control.

Emission sources and probabilistic health risk of volatile organic compounds emitted from production areas in a petrochemical refinery in Hainan, China

The emission sources and health risks of volatile organic compounds (VOCs) were analyzed and evaluated in a typical petrochemical refinery in Hainan, China. The sources and levels of 9 VOCs in five production areas were identified and qualified, and the probabilistic risk assessment method was employed to obtain more reasonable and scientific outcomes specifically realized by inhalation risk model and Monte Carlo simulation. Sensitivity and uncertainty analysis were also conducted to determine the influential factors in the risk evaluation process. The results indicated that for the refinery benzene, toluene, ethyl benzene, and xylene were the primary pollutants in these production areas, where the aromatic hydrocarbon extraction device (AHED) and xylene fractionation device areas are main contributors. In terms of non-carcinogenic risk, the largest hazard index existed in AHED area. The non-carcinogenic risk values for all production areas were not more than 1. The risk value of substances such as benzene still exceed the carcinogenic risk value of 10−6, indicating these substances existed potential carcinogenic risk to workers. Meanwhile, the findings can help to accumulate basic data for VOCs research in different installations of refineries, and provide evidence for VOCs pollution prevention and control.

SOURCE APPORTIONMENT OF VOCS BY RECEPTOR MODELLING IN AN URBAN SITE IN HA NOI

Volatile organic compounds (VOCs) are atmospheric pollutants of concern because of the health effect including carcinogenic risk of some of their species and the contribution in the formation of tropospheric ozone. The levels of VOCs in Hanoi were demonstrated to be higher than neighboring countries by previous research. The ozone potential formation (OFP) of VOCs was also some folds higher than others. Among transportation sources, VOCs were proved to be mainly emitted from motorbikes. The contribution percentages of transportation and other sources such as industrial, biomass burning sources are still remained unknown. In this research we applied chemical mass balance (CMB) receptor modelling to determine VOCs source apportionment. One week VOCs observation data at Hanoi University of Science and Technology in June 2017 was applied for investigation. Fourteen VOC species among 55 of which were applied for CMB modelling. Transportation and biomass burning source profiles were developed by monitoring in this study. Four other source profiles, namely gasoline evaporation, industrial production, cooking and paint that were compiled or calculated from previous studies. The results showed that the main sources of VOCs were vehicular emission, biomass burning, and gasoline evaporation contributing 37 %, 21 % and 20 % for VOCs levels, respectively. Other sources contributed for the leftover. The results can support to initiate policy for future control of VOCs.

Characteristics of Industrial VOCs Emission Sources and Control Technology Application in a Prefecture-level City Region-Based on Qinhuangdao City

Volatile organic compound (VOCs) emissions and control technologies of about 609 industrial enterprises in Qinhuangdao City were investigated in this study. The results showed that the exhausted emission flow rates from the industries of oil processing, coking, and nuclear fuel processing were found to be the largest sources of VOCs in Qinhuangdao City (normally above 105 m·h-1), whereas the other industrial emission flow rates were mainly within the range of 103-105 m3·h-1. The detected VOC concentrations for all the industries were less than 1000 mg·m-3. The VOCs emission rates were between 50-10000 g·h-1, but demonstrated different characteristics among the various industries. It was found that the industries of transportation equipment manufacturing, petroleum processing, coking, nuclear fuel processing, machinery and equipment manufacturing, printing and reproduction of recorded media, and chemical raw material and chemical product manufacturing had much higher concentrations and emission rates than other industries did. However, the overall VOCs emission level from this city was still lower when compared to previous reports for other regions of China. The investigation of the VOCs control technology application showed that there were 109 constructed or operated VOCs treatment facilities among the 609 industrial enterprises. Activated carbon adsorption technology accounted for the largest proportion among the various techniques, with 69%, followed by absorption technology (19%).

Using a Vegetative Environmental Buffer to Reduce the Concentrations of Volatile Organic Compounds in Poultry-House Atmospheric Emissions.

Ground-level ozone is formed when volatile organic compounds (VOCs) react with hydroxyl radicals and nitrogen oxides in the presence of ultraviolet light. Research has typically focused on the release and control of VOCs from hydrocarbon processing; however, agricultural activities, such as poultry production, can also be VOC sources and potentially contribute to ozone pollution. Therefore, this study examines the emission of C2-C6 VOCs from poultry houses and the use of a vegetative environmental buffer (VEB) as a potential mitigation strategy. Sampling campaigns were conducted at two farms, one with and one without a VEB. Of the nine compounds measured, methanol, ethanol, and acetone were the primary VOCs emitted and had the largest ozone-formation potential (OFP). A significantly larger decrease in the OFP for methanol as a function of distance from the poultry house was observed at the farm with the VEB as compared with at the farm without the VEB. These results suggest that besides being a visual barrier and particulate screen, VEBs can provide some control of VOCs emitted from poultry production.

Enhanced gaseous ethyl acetate degradation and power generation by a bioelectrochemical system

This work develops a novel hollow air-cathode biotrickling filter (BTF) microbial fuel cell (MFC) to treat ethyl acetate (EA) in a waste air stream. A BTF was combined with an MFC to form a BTF-MFC, which was effective in controlling volatile organic compounds (VOCs) emission and generating power. The BTF-MFC has an air cathode in its center, increasing the absorption and retention of water by the proton exchange membrane (PEM) to improve its ability to receive protons and oxygen and thereby accelerating the reduction reaction in the cathode. The EA removal efficiency was 17% higher under the close-circuit condition than the open-circuit condition, revealing the potential of the BTF-MFC for VOC control. Under optimum condition, a removal efficiency, maximum power density (PD), and maximum current density (CD) of 92.1%, 146.8 mW/m2, and 500.6 mA/m2, respectively, were obtained. The PD and CD were approximately five times, and the closed-circuit voltage (CCV) was 1.3 times, those obtained in the literature. Furthermore, MFC exhibited a linear increase in elimination capacity (EC) from 35.5 g/m3/h to 66.3 g/m3/h as the EA concentration under organic loading was increased from 36 to 72 g/m3/h under the critical load of about 70 g/m3/h and the maximum EC of 81 g/m3/h. This work establishes the feasibility of using both the improved PEM and a hollow air cathode to increase substantially the generation of electricity by an MFC and to remove EA with a relatively high efficiency.

VOCs Emission from Motor Vehicles in China and Its Impact on the Atmospheric Environment

Volatile organic compounds (VOCs) are important precursors of O3 and secondary organic aerosols (SOAs). In order to fully understand the impacts of VOCs from motor vehicles on urban air quality, the current state-of-the-art research results on source apportionment are systematically introduced. The contribution of VOCs from motor vehicles to secondary pollutants in China is further discussed. It was found that motor vehicle exhaust is the largest source of urban atmospheric VOCs, and the average contribution ratio is up to 36.8%, wherein motorcycles and light gasoline vehicles are the main emission sources. The results showed that VOCs from vehicles play an important role in O3 and SOA formation in urban areas, whereas with the improvement of emission standards and operating conditions, the motor vehicle emission factors and ozone formation potentials (OFPs) are obviously reduced. Moreover, the composition profile of the exhaust is mainly composed of aromatic hydrocarbons and alkenes, which contribute more to secondary pollution. This work can aid in providing data and theoretical support for the control of VOCs from motor vehicles in the future.

Control of VOCs from printing press air emissions by anaerobic bioscrubber: Performance and microbial community of an on-site pilot unit

A novel process consisted of an anaerobic bioscrubber was studied at the field scale for the removal of volatile organic compounds (VOCs) emitted from a printing press facility. The pilot unit worked under high fluctuating waste gas emissions containing ethanol, ethyl acetate, and 1-ethoxy-2-propanol as main pollutants, with airflows ranging between 184 and 1253 m3 h−1 and an average concentration of 1126 ± 470 mg-C Nm−3. Three scrubber configurations (cross-flow and vertical-flow packings and spray tower) were tested, and cross-flow packing was found to be the best one. For this packing, daily average values of VOC removal efficiency ranged between 83% and 93% for liquid to air volume ratios between 3.5·10−3 and 9.1·10−3. Biomass growth was prevented by periodical chemical cleaning; the average pressure drop was 165 Pa m−1. Rapid initiation of anaerobic degradation was achieved by using granular sludge from a brewery wastewater treatment plant. Despite the intermittent and fluctuating organic load, the expanded granular sludge bed reactor showed an excellent level of performance, reaching removal efficiencies of 93 ± 5% at 25.1 ± 3.2 °C, with biogas methane content of 94 ± 3% in volume. Volatile fatty acid concentration was as low as 200 mg acetic acid L−1 by treating daily average organic loads up to 3.0 kg COD h−1, equivalent to 24 kg COD m−3 bed d−1. The denaturing gradient gel electrophoresis (DGGE) results revealed the initial shift of the domains Archaea and Bacteria associated with the limitation of the carbon source to a few organic solvents. The Archaea domain was more sensitive, resulting in a drop of the Shannon index from 1.07 to 0.41 in the first 123 days. Among Archaea, the predominance of Methanosaeta persisted throughout the experimental period. The increase in the proportion of Methanospirillum and Methanobacterium sp. was linked to the spontaneous variations of operating temperature and load, respectively. Among Bacteria, high levels of ethanol degraders (Geobacter and Pelobacter sp.) were observed during the trial.

Spatial Distribution of Ozone Formation in China Derived from Emissions of Speciated Volatile Organic Compounds.

Ozone (O3) pollution is becoming increasingly severe in China. In addition, our limited understanding of the relationship between O3 and volatile organic compounds (VOCs), is an obstacle to improving air quality. By developing an improved source-oriented speciated VOC emission inventory in 2013, we estimated the ozone formation potential (OFP) and investigated its characteristics in China. Besides, a comparison was made between our estimates and space-based observations from the ozone monitoring instrument (OMI) on the National Aeronautics and Space Administration (NASA)'s Aura satellite. According to our estimates, m-/p-xylene, ethylene, formaldehyde, toluene, and propene were the five species that had the largest potential to form ozone, and on-road vehicles, industrial processes, biofuel combustion, and surface coating were the key contributing sectors. Among different regions of China, the North China Plain, Yangtze River Delta, and Pearl River Delta had the highest OFP values. Our results suggest that O3 formation is VOC-limited in major urban areas of China. Additionally, considering the different photochemical reactivities of various VOC species and the disparate energy and industry structures in the different regions of China, more efficient OFP-based and localized VOC control measures should be implemented, instead of the current mass-based and nationally uniform policies.

Emission characteristics of volatile organic compounds and their secondary organic aerosol formation potentials from a petroleum refinery in Pearl River Delta, China.

A campaign was carried out to measure the emission characteristics of volatile organic compounds (VOCs) in different areas of a petroleum refinery in the Pearl River Delta (PRD) region in China. In the refining area, 2-methylpentane, 2,3-dimethylbutane, methylcyclopentane, 3-methylhexane, and butane accounted for >50% of the total VOCs; in the chemical industry area, 2-methylpentane, p-diethylbenzene, 2,3-dimethylbutane, m-diethylbenzene and 1,2,4-trimethylbenzene were the top five VOCs detected; and in the wastewater treatment area, the five most abundant species were 2-methylpentane, 2,3-dimethylbutane, methylcyclopentane, 3-methylpentane and p-diethylbenzene. The secondary organic aerosol (SOA) formation potential was estimated using the fractional aerosol coefficients (FAC), secondary organic aerosol potential (SOAP), and SOA yield methods. The FAC method suggests that toluene, p-diethylbenzene, and p-diethylbenzene are the largest contributors to the SOA formation in the refining, chemical industry, and wastewater treatment areas, respectively. With the SOAP method, it is estimated that toluene is the largest contributor to the SOA formation in the refining area, but o-ethyltoluene contributes the most both in the chemical industry and wastewater treatment areas. For the SOA yield method, aromatics dominate the yields and account for nearly 100% of the total in the three areas. The SOA concentrations estimated of the refining, chemical industry and wastewater treatment areas are 30, 3835 and 137μgm-3, respectively. Despite the uncertainties and limitations associated with the three methods, the SOA yield method is suggested to be used for the estimation of SOA formation from the petroleum refinery. The results of this study have demonstrated that the control of VOCs, especially aromatics such as toluene, ethyltoluene, benzene and diethylbenzene, should be a focus of future regulatory measures in order to reduce PM pollution in the PRD region.

Toluene, Methanol and Benzaldehyde Removal from Gas Streams by Adsorption onto Natural Clay and Faujasite-Y type Zeolite.

A great number of pollution problems come as a result of the emission of Volatile Organic Compounds (VOCs) into the environment and their control becomes a serious challenge for the global chemical industry. Adsorption is a widely used technique for the removal of VOCs due to its high efficiency, low cost, and convenient operation. In this study, the feasibility to use a locally available clay, as adsorbent material to control VOCs emissions is evaluated. Natural clay is characterised by different physical-chemical methods and adsorptive interaction features between VOCs and natural clay are identified. Toluene (T), methanol (M) and benzaldehyde (B) are used here as representatives of three different kinds of VOCs. Adsorption isotherms onto natural clay and faujasite-Y type zeolite (Fau Y) are obtained at room temperature. According to Langmuir model data, maximum adsorption capacities (qm) of Fez natural clay and zeolite toward methanol (M), toluene (T) and benzaldehyde (B) at 300 K are 8, 0.89 and 3.1 mmol g-1, and 15, 1.91 and 13.9 mmol g-1 respectively. In addition, the effect of temperature on the adsorption of toluene onto natural clay is evaluated in the range from 300 to 323K. An increase on temperature reduces the adsorption capacity of natural clay toward toluene, indicating that an exothermic physical adsorption process takes place. The enthalpy of adsorption of toluene onto Fez natural clay was found to be -54 kJ mol-1. A preliminary cost analysis shows that natural clay could be used as an alternative low cost adsorbent in the control of VOCs from contaminated gas streams with a cost of US$ 0.02 kg-1 compared to Fau Y zeolite with US$ 10 kg-1.

Photo-Catalytic Oxidation Technology for VOC Control: Evaluation and Risk Characterization of Intermediates of Benzene Degradation Adsorbed on Catalyst

Abstract A sol-gel-based TiO2-coated photo-catalytic device was developed and demonstrated for field applications for controlling volatile organic compounds (VOCs) in three varying indoor environments: (i) laboratory using benzene (efficiency >99%), (ii) conference room of an industry producing organic solvents (mono, di, and tri chloro benzene) (efficiency >70%), and (iii) chemistry laboratory using multiple solvents/VOCs (efficiency >88%). The VOC degradation rate constant for coexisting multiple VOC was estimated to be 1.06/min/m2, which was about 34% less than that of benzene. A VOC mass balance model was developed to describe interaction between indoor air and kinetics of VOC degradation to estimate required extent of treatment for safe VOC concentration in the indoor air. Toxic intermediates of benzene that were adsorbed on the catalyst surface (solid phase) were identified and quantified with GC/GC-MS (gas chromatography-mass spectroscopy). Intermediates accounted for less than 5% of the total mass...

Ozone production and its sensitivity to NO&amp;lt;sub&amp;gt;&amp;lt;i&amp;gt;x&amp;lt;/i&amp;gt;&amp;lt;/sub&amp;gt; and VOCs: results from the DISCOVER-AQ field experiment, Houston 2013

Abstract. An observation-constrained box model based on the Carbon Bond mechanism, version 5 (CB05), was used to study photochemical processes along the NASA P-3B flight track and spirals over eight surface sites during the September 2013 Houston, Texas deployment of the NASA Deriving Information on Surface Conditions from COlumn and VERtically Resolved Observations Relevant to Air Quality (DISCOVER-AQ) campaign. Data from this campaign provided an opportunity to examine and improve our understanding of atmospheric photochemical oxidation processes related to the formation of secondary air pollutants such as ozone (O3). O3 production and its sensitivity to NOx and volatile organic compounds (VOCs) were calculated at different locations and times of day. Ozone production efficiency (OPE), defined as the ratio of the ozone production rate to the NOx oxidation rate, was calculated using the observations and the simulation results of the box and Community Multiscale Air Quality (CMAQ) models. Correlations of these results with other parameters, such as radical sources and NOx mixing ratio, were also evaluated. It was generally found that O3 production tends to be more VOC-sensitive in the morning along with high ozone production rates, suggesting that control of VOCs may be an effective way to control O3 in Houston. In the afternoon, O3 production was found to be mainly NOx-sensitive with some exceptions. O3 production near major emissions sources such as Deer Park was mostly VOC-sensitive for the entire day, other urban areas near Moody Tower and Channelview were VOC-sensitive or in the transition regime, and areas farther from downtown Houston such as Smith Point and Conroe were mostly NOx-sensitive for the entire day. It was also found that the control of NOx emissions has reduced O3 concentrations over Houston but has led to larger OPE values. The results from this work strengthen our understanding of O3 production; they indicate that controlling NOx emissions will provide air quality benefits over the greater Houston metropolitan area in the long run, but in selected areas controlling VOC emissions will also be beneficial.

Significant increase of summertime ozone at Mount Tai in Central Eastern China

Abstract. Tropospheric ozone (O3) is a trace gas playing important roles in atmospheric chemistry, air quality and climate change. In contrast to North America and Europe, long-term measurements of surface O3 are very limited in China. We compile available O3 observations at Mt. Tai – the highest mountain over the North China Plain – during 2003–2015 and analyze the decadal change of O3 and its sources. A linear regression analysis shows that summertime O3 measured at Mt. Tai has increased significantly by 1.7 ppbv yr−1 for June and 2.1 ppbv yr−1 for the July–August average. The observed increase is supported by a global chemistry-climate model hindcast (GFDL-AM3) with O3 precursor emissions varying from year to year over 1980–2014. Analysis of satellite data indicates that the O3 increase was mainly due to the increased emissions of O3 precursors, in particular volatile organic compounds (VOCs). An important finding is that the emissions of nitrogen oxides (NOx) have diminished since 2011, but the increase of VOCs appears to have enhanced the ozone production efficiency and contributed to the observed O3 increase in central eastern China. We present evidence that controlling NOx alone, in the absence of VOC controls, is not sufficient to reduce regional O3 levels in North China in a short period.

Response surface modeling-based source contribution analysis and VOC emission control policy assessment in a typical ozone-polluted urban Shunde, China

To develop a sound ozone (O3) pollution control strategy, it is important to well understand and characterize the source contribution due to the complex chemical and physical formation processes of O3. Using the “Shunde” city as a pilot summer case study, we apply an innovative response surface modeling (RSM) methodology based on the Community Multi-Scale Air Quality (CMAQ) modeling simulations to identify the O3 regime and provide dynamic analysis of the precursor contributions to effectively assess the O3 impacts of volatile organic compound (VOC) control strategy. Our results show that Shunde is a typical VOC-limited urban O3 polluted city. The “Jiangmen” city, as the main upper wind area during July 2014, its VOCs and nitrogen oxides (NOx) emissions make up the largest contribution (9.06%). On the contrary, the contribution from local (Shunde) emission is lowest (6.35%) among the seven neighbor regions. The local VOCs industrial source emission has the largest contribution comparing to other precursor emission sectors in Shunde. The results of dynamic source contribution analysis further show that the local NOx control could slightly increase the ground O3 under low (10.00%) and medium (40.00%) reduction ratios, while it could start to turn positive to decrease ground O3 under the high NOx abatement ratio (75.00%). The real-time assessment of O3 impacts from VOCs control strategies in Pearl River Delta (PRD) shows that the joint regional VOCs emission control policy will effectively reduce the ground O3 concentration in Shunde.

Indoor pollutant exposure among children with and without asthma in Porto, Portugal, during the cold season.

Considering the time spent in enclosed spaces, indoor air pollutants are of major interest because of its possible impact on health. However, to date, few studies have analysed the air concentrations of a large set of indoor pollutants of respiratory health relevance in dwellings, particularly in Portugal. This study aimed to measure the concentrations of air pollutants that are present in residential buildings and to investigate whether some clustering pattern of indoor air pollutants exists in the dwellings of children with (case group) and without asthma (control group). Measurements were taken in 30 and 38 dwellings of asthmatic and non-asthmatic schoolchildren, respectively, located in the city of Porto, Portugal, during the cold season (October 2012-April 2013), to assess the concentrations of 12 volatile organic compounds (VOC), aldehydes, PM2.5, PM10, bacteria and fungi. Toluene, d-limonene, formaldehyde, PM2.5, bacteria and fungi are widely present in dwellings, sometimes in relatively high concentrations in reference to WHO guideline values. Moreover, concentrations of CO2 exceeding 1000ppm were often encountered, indicating that 70% of all dwellings had poor ventilation (<4L/s person). While exposures to common dwelling indoor pollutants are similar for schoolchildren with and without asthma, except for d-limonene levels, the identification and control of VOC and PM sources is important and prudent, especially for vulnerable individuals.

Plant defence responses to volatile alert signals are population‐specific

Herbivore‐induced volatiles are widespread in plants. They can serve as alert signals that enable neighbouring leaves and plants to pre‐emptively increase defences and avoid herbivory damage. However, our understanding of the factors mediating volatile organic compound (VOC) signal interpretation by receiver plants and the degree to which multiple herbivores affect VOC signals is still limited. Here we investigated whether plant responses to damage‐induced VOC signals were population specific. As a secondary goal, we tested for interference in signal production or reception when plants were subjected to multiple types of herbivore damage. We factorially crossed the population sources of paired Phaseolus lunatus plants (same versus different population sources) with a mechanical damage treatment to one member of the pair (i.e. the VOC emitter, damaged versus control), and we measured herbivore damage to the other plant (the VOC receiver) in the field. Prior to the experiment, both emitter and receiver plants were naturally colonized by aphids, enabling us to test the hypothesis that damage from sap‐feeding herbivores interferes with VOC communication by including emitter and receiver aphid abundances as covariates in our analyses. One week after mechanical leaf damage, we removed all the emitter plants from the field and conducted fortnightly surveys of leaf herbivory. We found evidence that receiver plants responded using population‐specific ‘dialects’ where only receivers from the same source population as the damaged emitters suffered less leaf damage upon exposure to the volatile signals. We also found that the abundance of aphids on both emitter and receiver plants did not alter this volatile signalling during both production and reception despite well‐documented defence crosstalk within individual plants that are simultaneously attacked by multiple herbivores. Overall, these results show that plant communication is highly sensitive to genetic relatedness between emitter and receiver plants and that communication is resilient to herbivore co‐infestation.