Indoor Carbonyl Research Articles

Molecular Characteristics, Sources, and Health Risk Assessment of Gaseous Carbonyl Compounds in Residential Indoor and Outdoor Environments in a Megacity of Northwest China

Carbonyl compounds (CCs) in indoor air pose a significant threat to residents’ health and have garnered considerable attention in recent years. However, most studies have focused on low-molecular-weight carbonyl compounds (LMW-CCs) and have underestimated the impact of high-molecular-weight ones (HMW-CCs), causing a failure to comprehensively understand their effects on health. In this study, we analyzed twenty carbonyls in the indoor and outdoor air at typical residential communities in a megacity in Northwest China by using high-performance liquid chromatography (HPLC) coupled with a photodiode array detector (DAD). The total concentration of indoor carbonyls was 1.4-3.4 times that of outdoor carbonyls. In addition, the concentration of indoor carbonyls was much higher during the heating season than that during the nonheating season. Conversely, the concentration of outdoor carbonyls was higher during the nonheating season than that during the heating season. The principal component analysis (PCA) revealed that indoor carbonyl pollution was primarily influenced by building materials, cooking fume, and wooden furniture. Formaldehyde exposure in indoor environments posed a greater health risk to children than acetaldehyde exposure. HMW-CCs were the primary contributors to indoor odor pollution, which was considered a significant cause of sick building syndrome (SBS). Our findings underscore the crucial role of HMW-CCs in indoor environments in exerting adverse impacts on health.

Urban residential indoor volatile organic compounds in summer, Beijing: Profile, concentration and source characterization

Residential indoor exposure to volatile organic compounds (VOCs) is a major public health concern. However, the relevant pollution sources have not been well characterized in China. In this study, the 24-h integrated concentrations of 55 VOC species in 27 urban residences, Beijing were measured in the summer. The sources were characterized with positive matrix factorization (PMF) and general linear model (GLM). The most abundant species in terms of geometric mean concentration were formaldehyde (55.1 μg/m3), acetaldehyde (18.7 μg/m3), acetone (14.8 μg/m3), toluene (14.1 μg/m3), hexanal (13.8 μg/m3), n-hexadecane (8.9 μg/m3) and n-pentadecane (8.5 μg/m3). PMF generated 7 factors associated with VOC sources, including aldehydes from ozone-initiated secondary reactions, butyraldehyde from hydrolysis of building materials and furniture, wood flooring emission, wooden furniture emission, wall coverings emission, mobile emission and halogenated hydrocarbons of miscellaneous outdoor origin. GLM identified leather sofa as another source of indoor terpenes and formaldehyde. GLM also found composite wood flooring had stronger emission of VOCs than solid wood flooring, except 1,4-dichlorobenzene. A comparison with multiple studies across the world suggested that: (1) more intensive ozone-initiated secondary reactions resulted in the significantly higher indoor carbonyl concentrations in Beijing than in Japan and USA in the summer; (2) the indoor concentrations of benzene and C12-C17 alkanes were much higher in Beijing, due to the traffic conditions and prevalent use of wood flooring varnishing.

Environmental conditions in homes with healthy and unhealthy schoolchildren in Beijing, China

In 2013, a comprehensive investigation of environmental conditions was carried out in schoolchildren's houses during winter and summer in Beijing, China. The houses were divided into two Groups (Group A: unhealthy children's houses; Group B: healthy children's houses). According to the field measurement, inappropriate thermal environment contributed by indoor low temperatures and RHs in winter and dampness in summer could affect childhood health. The beyond standard (1000 ppm) situations of CO2 concentration revealed poor ventilation in houses of Group A, which could increase the risk of children's asthma and respiratory infections. Indoor carbonyls and VOCs levels in almost all the homes did not exceed the guideline. However, the integrated influence of these compounds should be noted for possible adverse health effects, especially in child's bedroom where children spent more time. Dibutyl phthalate (DBP) and Di (2-ethylhexyl) phthalate (DEHP) were most frequently detected SVOCs in house dust. In summer, the average child's daily intake of phthalates from house dust in homes of Group A was significantly higher (p < 0.01) than that of Group B. Cladosporium spp., Penicillium spp. and Aspergillus spp. accounted for about 90% of indoor airborne fungi. Airborne fungal levels in about 70% of measured rooms exceeded 1000 cfu/m3 in summer. The high correlation between airborne fungi and PM was found, consequently, children's health could be affected by the combined action of airborne fungi and PM. These results were helpful to evaluate and design healthy housing environment for schoolchildren.

Measurement and health risk assessment of PM2.5, flame retardants, carbonyls and black carbon in indoor and outdoor air in kindergartens in Hong Kong

Indoor air pollution is closely related to children's health. Polybrominated diphenyl ethers (PBDEs) and dechlorane plus (DP) transmitted through indoor PM2.5 and dust, along with carbonyl compounds and black carbon (BC) aerosol were analysed in five Hong Kong kindergartens. The results showed that 60% of the median PM2.5 levels (1.3×101 to 2.9×101μg/m3 for indoor; 9.5 to 8.8×101μg/m3 for outdoor) in the five kindergartens were higher than the guidelines set by the World Health Organization (2.5×101μg/m3). Indoor PM2.5 mass concentrations were correlated with outdoor PM2.5 in four of the kindergartens. The PBDEs (0.10–0.64ng/m3 in PM2.5; 0.30–2.0×102ng/g in dust) and DP (0.05–0.10ng/m3 in PM2.5; 1.3–8.7ng/g in dust) were detected in 100% of the PM2.5 and dust samples. Fire retardant levels in the air were not correlated with the levels of dust in this study. The median BC concentrations varied by >7-fold from 8.8×102ng/m−3 to 6.7×103ng/m−3 and cooking events might have caused BC concentrations to rise both indoors and outdoors. The total concentrations of 16 carbonyls ranged from 4.7×101μg/m3 to 9.3×101μg/m3 indoors and from 1.9×101μg/m3 to 4.3×101μg/m3 outdoors, whilst formaldehyde was the most abundant air carbonyl. Indoor carbonyl concentrations were correlated with outdoor carbonyls in three kindergartens. The health risk assessment showed that hazard indexes (HIs) HIs of non-cancer risks from PBDEs and DPs were all lower than 0.08, whilst non-cancer HIs of carbonyl compounds ranged from 0.77 to 1.85 indoors and from 0.50 to 0.97 outdoors. The human intake of PBDEs and DP through inhalation of PM2.5 accounted for 78% to 92% of the total intake. The cancer hazard quotients (HQs) of formaldehyde ranged from 4.5E−05 to 2.1E−04 indoors and from 1.9E−05 to 6.2E−05 outdoors. In general, the indoor air pollution in the five Hong Kong kindergartens might present adverse effects to children, although different schools showed distinct pollution levels, so indoor air quality might be improved through artificial measures. The data will be useful to developing a feasible management protocol for indoor environments.

Partition of the carbonyl compounds between the indoor and outdoor air at residental areas in District 5, Ho Chi Minh City

Indoor air pollution, especially for the air toxic compounds such as carbonyls, is the most common issue in large cities. Indoor and outdoor air samples were simultaneously collected at six homes to estimate the pollution levels of carbonyl compounds at some points in the residential area, Ho Chi Minh City. The gaseous carbonyls were measured in the period of August and September, 2011 corresponding to the rainy season. The results showed that formaldehyde, acetaldehyde and acetone were the most abundant carbonyls in both indoor and outdoor air, accounted 80 % of the interested compounds, followed by propionaldehyde and benzaldehyde. In the outdoor air, the mean concentrations of formaldehyde, acetaldehyde and acetone were 15.21±6.42, 13.77±7.63, 12.11±11.72 μg.m-3, respectively. Meanwhile, the indoor concentrations were 25.45±19.49, 26.21±13.03 and 22.12±18.08 μg.m-3 for formaldehyde, acetaldehyde and acetone, respectively. Formaldehyde/acetaldehyde and acetaldehyde/ propionaldehyde ratios were 2.23±1.41 and 6.09±5.00, respestively, indicating that main sources of outdoor carbonyls came from the anthropogenic source. The mean carbonyl concentrations of the present study compared with those of other countries showed that indoor carbonyls were similar to other studies, but outdoor carbonyls were much higher. In addition, most of the indoor/outdoor ratios were slightly higher than 1 and levels of benzaldehyde and tolualdehyde were a little high in the indoor air. These results indicated that the indoor carbonyls were strongly affected by the outdoor air infiltration.

Levels and Health Risk of Carbonyl Compounds in Air of the Library in Guangzhou, South China

ABSTRACTThe concentrations of 18 carbonyl compounds and their health risks for people were investigated in indoor and outdoor air of three different rooms of a library in Guangzhou, South China. Indoor air samples were collected during normal activities of staff and students, and carbonyl compounds were analyzed by high-performance liquid chromatography. The results show that the total concentrations of 18 carbonyls ranged from 8.8 to 73.9 µg m–3 with a mean value of 24.7 µg m–3. Acetone was the most abundant species with a mean value of 10.8 µg m–3 in indoor air, followed by formaldehyde and acetaldehyde. The levels of carbonyls in this study were relatively lower than most of other microenvironments in the literature. The average total concentration of carbonyls in the electronic reading room was higher than those in stack room and compact stack room. Diurnal variation in carbonyl concentrations was not distinct in the three rooms. The indoor/outdoor ratios and Spearman correlation coefficients demonstrated that endogenous emission sources contributed significantly to most of indoor carbonyls, while outdoor infiltration might be one of the main sources for acetaldehyde. The personal exposure, lifetime cancer risk, and non-cancer chronic health impacts through inhalation associated with formaldehyde and acetaldehyde were estimated and discussed.

Study on the air pollution in typical transportation microenvironment: Characteristics and health risks

The concentration of formaldehyde in micro-traffic atmospheric environment (including buses, cars, bus stations, and traffic artery) of Lin’an City was carefully investigated. The results showed that the formaldehyde average concentration was 0.0162 mg/m3 in the buses, 0.0225 mg/m3 in the cars, 0.0047 mg/m3 in the West Bus Stations, and 0.0133 mg/m3 in the East Bus Stations. The concentration of formaldehyde along the traffic artery decreased with the height increased. From 0 to 140 cm, the formaldehyde concentration decreased from 0.031 to 0.018 mg/m3. The formaldehyde concentration decreased when far away from the traffic artery. When the distance reached 200 m, the formaldehyde concentration decreased from 0.018 to 0.005 mg/m3. Based on the health risk assessment model, using 1 hr as the average retention time, the average health risk in buses, cars, and West/East Bus Stations was 2.106 × 10−4, 2.925 × 10−4, and 1.157 × 10−4, respectively.Implications: The data of carbonyl concentrations in transportation microenvironment in China are limited. In this paper, the authors investigated carbonyl levels in selected transportation microenvironment, discussed the possible sources of indoor carbonyls, and assessed health risks for carbonyls inside transportation microenvironment.

Evaluation of hazardous airborne carbonyls on a university campus in southern China

A comprehensive assessment of indoor carbonyl compounds for the academic staff, workers, and students was conducted on a university campus in Xiamen, China. A total of 15 representative environment categories, including 12 indoor workplaces and three residential units, were selected. The potential indoor pollution sources were identified based on the variability in the molar compositions and correlation analyses for the target carbonyls. Furnishing materials, cooking emissions, and electronic equipment, such as photocopiers, can generate various carbonyls in the workplace. Comparison studies were conducted in the clerical offices, demonstrating that off-gases from wooden furniture and lacquer coatings, environmental tobacco smoke (ETS), and the use of cleaning reagents elevated the indoor carbonyl levels. The measured concentrations of formaldehyde and acetaldehyde in most locations surpassed the exposure limit levels. The lifetime cancer hazard risk (R) associated with formaldehyde was above the concern risk level (1 × 10−6) in all of the workplaces. The results indicate that formaldehyde exposure is a valid occupational health and safety concern. Wooden furniture and refurbishing materials can pose serious health threats to occupants. The information in this study could act as a basis for future indoor air quality monitoring in Mainland China.Implications:A university campus represents a microscale city environment consisting of all the working, living, and commercial needs of staff and students. The scope of this investigation covers 21 hazardous carbonyl species based on samples collected from 15 categories of workplaces and residential building in a university campus in southern China. Findings of the study provide a comprehensive assessment of indoor air quality with regards to workers’ health and safety. No similar study has been carried out in China.

Highly efficient indoor air purification using adsorption-enhanced-photocatalysis-based microporous TiO2 at short residence time

A short residence time is a key design parameter for the removal of organic pollutants in catalyst-based indoor air purification systems. In this study, we synthesized a series of TiO2 with different micropore volumes and studied their removal efficiency of indoor carbonyl pollutants at a short residence time. Our results indicated that the superior adsorption capability of TiO2 with micropores improved its performance in the photocatalytic degradation of cyclohexanone, while the photocatalytic removal of the pollutant successfully kept porous TiO2 from becoming saturated. When treated with 1 mg m−3 cyclohexanone at a relatively humidity of 18%, the adsorption amount on microporous TiO2 was 5.4–7.9 times higher than that on P25. Removal efficiency via photocatalysis followed the same order as the adsorption amount: TiO2-5 > TiO2-20 > TiO2-60 > TiO2-180>P25. The advantage of microporous TiO2 over P25 became more pronounced when the residence time declined from 0.072 to 0.036 s. Moreover, as the concentration of cyclohexanone deceased from 1000 ppb to 500 ppb, removal efficiency by microporous TiO2 increased more rapidly than P25.

Indoor carbonyl compounds in an academic building in Beijing, China: concentrations and influencing factors

Carbonyl compounds in indoor air are of great concern for their adverse health effects. Between February and May, 2009, concentrations of 13 carbonyl compounds were measured in an academic building in Beijing, China. Total concentration of the detected carbonyls ranged from 20.7 to 189.1 μg·m−3, and among them acetone and formaldehyde were the most abundant, with mean concentrations of 26.4 and 22.6 μg·m−3, respectively. Average indoor concentrations of other carbonyls were below 10 μg·m−3. Principal component analysis identified a combined effect of common indoor carbonyl sources and ventilation on indoor carbonyl levels. Diurnal variations of the carbonyl compounds were investigated in one office room, and carbonyl concentrations tended to be lower in the daytime than at night, due to enhanced ventilation. Average concentrations of carbonyl compounds in the office room were generally higher in early May than in late February, indicating the influence of temperature. Carbonyl source emission rates from both the room and human occupants were estimated during two lectures, based on one-compartment mass balance model. The influence of human occupants on indoor carbonyl concentrations varies with environmental conditions, and may become significant in the case of a large human occupancy.

Emission Sources and their Contribution to Indoor Air Pollution by Carbonyl Compounds in a School and a Residential Building in Shizuoka, Japan

A simple method for screening indoor emission sources of carbonyl compounds developed previously by the authors was used for this study. The new device, which is called “emission cell for simultaneous multisampling” (ECSMS), was used for flux sampling of volatile carbonyl compounds from surfaces of building and furnishing materials in situ. Indoor carbonyl concentrations in various rooms at a school and residential building in Shizuoka, Japan, were investigated in 2006 using the developed techniques. In several rooms, formaldehyde concentrations exceeded the air quality guideline value (100 µg m−3) set by the World Health Organization. The formaldehyde emission rates from the various surfaces in those rooms were determined using the ECSMS units. The furniture was found to be the major emission source of formaldehyde emission in many of the rooms; emissions from the furniture accounted for 42–79% of each room’s total emissions. On the basis of the results, a strategy to reduce the indoor formaldehyde concentrations in each room is proposed by this paper. This study confirmed that the ECSMS can be used for on-site screening of primary emission sources of formaldehyde that could cause indoor air pollution.

Predicting personal exposure to airborne carbonyls using residential measurements and time/activity data

As a part of the Relationships of Indoor, Outdoor, and Personal Air (RIOPA) study, 48 h integrated residential indoor, outdoor, and personal exposure concentrations of 10 carbonyls were simultaneously measured in 234 homes selected from three US cities using the Passive Aldehydes and Ketones Samplers (PAKS). In this paper, we examine the feasibility of using residential indoor concentrations to predict personal exposures to carbonyls. Based on paired t-tests, the means of indoor concentrations were not different from those of personal exposure concentrations for eight out of the 10 measured carbonyls, indicating indoor carbonyls concentrations, in general, well predicted the central tendency of personal exposure concentrations. In a linear regression model, indoor concentrations explained 47%, 55%, and 65% of personal exposure variance for formaldehyde, acetaldehyde, and hexaldehyde, respectively. The predictability of indoor concentrations on cross-individual variability in personal exposure for the other carbonyls was poorer, explaining<20% of variance for acetone, acrolein, crotonaldehyde, and glyoxal. A factor analysis, coupled with multiple linear regression analyses, was also performed to examine the impact of human activities on personal exposure concentrations. It was found that activities related to driving a vehicle and performing yard work had significant impacts on personal exposures to a few carbonyls.

Characteristics of carbonyls: Concentrations and source strengths for indoor and outdoor residential microenvironments in China

Indoor and outdoor carbonyl concentrations were measured simultaneously in 12 urban dwellings in Beijing, Shanghai, Guangzhou, and Xi’an, China in summer (from July to September in 2004) and winter (from December 2004 to February 2005). Formaldehyde was the most abundant indoor carbonyls species, while formaldehyde, acetaldehyde and acetone were found to be the most abundant outdoor carbonyls species. The average formaldehyde concentrations in summer indoor air varied widely between cities, ranging from a low of 19.3 μg m −3 in Xi’an to a high of 92.8 μg m −3 in Beijing. The results showed that the dwellings with tobacco smoke, incense burning or poor ventilation had significantly higher indoor concentrations of certain carbonyls. It was noticed that although one half of the dwellings in this study installed with low emission building materials or furniture, the carbonyls levels were still significantly high. It was also noted that in winter both the indoor and outdoor acetone concentrations in two dwellings in Guangzhou were significantly high, which were mainly caused by the usage of acetone as industrial solvent in many paint manufacturing and other industries located around Guangzhou and relatively longer lifetime of acetone for removal by photolysis and OH reaction than other carbonyls species. The indoor carbonyls levels in Chinese dwellings were higher than that in dwellings in the other countries. The levels of indoor and ambient carbonyls showed great seasonal differences. Six carbonyls species were carried out the estimation of indoor source strengths. Formaldehyde had the largest indoor source strength, with an average of 5.25 mg h −1 in summer and 1.98 mg h −1 in winter, respectively. However, propionaldehyde, crotonaldehyde and benzaldehyde had the weakest indoor sources.

Characteristics of carbonyl compounds in public vehicles of Beijing city: Concentrations, sources, and personal exposures

The characteristics of carbonyl compounds (carbonyls) including concentrations, major sources, and personal exposure were investigated for 29 vehicles including taxi, bus and subway in Beijing. It was found that the taxis (Xiali, TA) and buses (Huanghe, BA) fueled by gasoline with longer service years had the higher indoor carbonyl levels (178±42.7 and 188±31.6 μg m −3) while subways energized by electricity without exhaust and the jingwa buses (BB) driven in the suburb had the lower levels with total concentrations of 98.5±26.3 and 92.1±20.3 μg m −3, respectively. Outdoor carbonyls of taxi cars and buses were nearly at the same level with their total concentrations varying from 80 to 110 μg m −3. The level of outdoor subways carbonyls was equal with the ambient air levels. Exhaust leakage, indoor material emissions, photochemical formation, and infiltration of outdoor air were considered to be the major sources to in-vehicle carbonyls. Personal exposures and cancer risk to formaldehyde and acetaldehyde were calculated for professional bus and taxi drivers, respectively. Taxi drivers had the highest cancer risk with personal exposure to formaldehyde and acetaldehyde of 212 and 243 μg day −1, respectively. The public concern should pay considerable attention to professional drivers’ health.

Measurement of indoor-outdoor carbonyls at four residential homes in Mexico City metropolitan area

Formaldehyde, acetaldehyde, acetone, propionaldehyde and butyraldehyde were measured in indoor and outdoor air at three houses and one apartment in the Mexico city metropolitan area (MCMA). Formaldehyde presented the highest concentration in indoor and outdoor air, followed by acetone and acetaldehyde. Indoor carbonyl concentrations were higher than outdoor concentrations at all sampling sites. Indoor exposure factors were estimated for formaldehyde and acetaldehyde, ranging from 202 µg day–1 to 554 µg day–1 for formaldehyde and from 82 µg day–1 to 202 µg day–1 for acetaldehyde. Indoor-outdoor correlations were significant at all sites. However, these correlations were the highest in the Miguel Hidalgo house, which was naturally well ventilated, and where very few activities like cooking, were done. Concerning the Tlalnepantla house, although it was also well ventilated, the correlations were not as high as those observed at the Miguel Hidalgo house, possibly because its inhabitants cook a lot more and throughout the whole day.

Measuring the Effect of Photocatalytic Purifiers on Indoor Air Hydrocarbons and Carbonyl Pollutants

Laboratory tests of photocatalytic air purifiers are usually performed with a single pollutant, in the parts per million by volume domain and at airflow rates [H11349]0.1 m3/hr. Clearly, it is necessary to probe photocatalytic materials and apparatuses under real conditions or conditions closely mimicking reality. Photocatalytic prototypes were placed in an ordinary room. To collect hydrocarbons over a shorter period (15 min) than with adsorbent-containing cartridges, solid-phase microextraction (SPME) was used. Typically, concentrations in substituted benzene hydro-carbons and tetrachloroethene were decreased to 20–35% of initial values; toluene and m- [H11001] p-xylene concentrations dropped to 2–6 parts per billion by volume, and o-xylene and benzene concentrations were still lower. In the absence of appropriate, commercialized SPME fibers, carbonyl compounds (both formed and destroyed by photocatalysis) were extracted using cartridges containing 2,4- dinitrophenylhydrazine-coated silica. The concentration ranges (in parts per billion by volume) were shifted to higher values in treated air: from 9–15.5 to 12.5–18 for methanal, from 1.5–3 to 8–11.5 for ethanal, and from 4.5–19 to 8–26.5 for propanone with the prototype used; these unprecedented results do not exclude using photo-catalysis to treat air, but they illustrate that improvement is needed. Because these tests are time-consuming, preliminary tests are useful; results obtained with a 225-L closed-loop, airtight, photocatalytic reactor with an external turbine enabling the ambient air inside the reactor to be circulated through the purifier device at 15–450 m3/hr flow rates are reported.

Measurements of carbonyls in a 13-story building

Formaldehyde and acetaldehyde are emitted by many mobile and stationary sources and secondary aldehydes are intermediates in the photo-oxidation of organic compounds in the atmosphere. These aldehydes are emitted indoors by many materials such as furniture, carpets, heating and cooling systems, an by smoking. Carbonyls, mainly formaldehyde and acetaldehyde, have been studied because of their adverse health effects. In addition, formaldehyde is a suspected carcinogen. Therefore, the concentrations of formaldehyde and acetaldehyde were determined to assess the inhalation exposure doses to carbonyls for people who work in a 13-story building and in order to evaluate the cancer hazard. Carbonyl compounds in indoor and outdoor air were measured at a 13-story building located in Mexico City. The mezzanine, fifth and tenth floors, and the third level-parking garage were selected for sampling. Samples were collected in two sampling periods, the first from April 20 to 29, 1998 and the second from December 1 to 20, 1998. Carbonyls were sampled by means of DNHP-coated cartridges at a flow rate of 1 l min(-1) from 9:00 to 19:00 hours, during 2-hour time intervals and analyzed by HPLC with hours, during 2-hour time intervals and analyzed by HPLC with UV/VIS detection. Mean carbonyl concentrations were highest in the 3rd level-parking garage, with the formaldehyde concentration being the highest ranging from 108 to 418 microg m(-3). In working areas, the highest carbonyl arithmetic mean concentrations (AM) were observed on the 5th floor. Acetone and formaldehyde concentrations were highest in April ranging from 161 to 348 microg m(-3) (AM = 226) and from 157 to 270 microg m(-3) (AM = 221), respectively. Propionaldehyde and butyraldehyde were present in smaller concentrations ranging from 2 to 25 and 1 to 28 microg m(-3), respectively, considering all the samples. Mean indoor/outdoor ratios of carbonyls ranged from 1.8 to 9.6. A reduction of inhalation exposure doses of 41% and 45% was observed in the fifth floor air after the air conditioning systems had been repaired. Formaldehyde and acetaldehyde concentrations were higher in smoking environments. Indoor carbonyl concentrations were significantly greater than outdoor concentrations. Tobacco smoke seems to be the main indoor source of formaldehyde. After the air conditioning system was maintained and repaired (as was recommended), an important reduction in the emission of formaldehyde and acetaldehyde was achieved on all floors, except for the 3rd level parking garage, thereby reducing the inhalation exposure doses. The results obtained in this research demonstrated that maintenance of air conditioning systems must be carried out regularly in order to avoid possible adverse effects on health. Additionally, it is mandatory that isolated smoking areas, with air extraction systems, be installed in every public building.

Presença de compostos carbonílicos no ar em ambientes internos na cidade de São Paulo

The presence of low carbonyl compounds (C1-C4) and glutaraldehyde was observed in 14 work-locations in Sao Paulo city, Brazil, during January to July 1997 period. The quantification of other carbonyls was not possible due to a sampling artifact caused probably by undesirable reactions between the ambient ozone and the organic substract of C18 cartridge used to collect carbonyls. High indoor concentrations, compared to outdoor levels, were observed for all compounds. Formaldehyde was the most abundant species (29 ppb) followed by acetone and acetaldehyde (25 and 17 ppb) with a small contribution of propanal, crotonaldehyde and C4 isomers (0.7 to 1.5 ppb) when related to the total indoor carbonyls level. Glutaraldehyde was observed only in two different occupational locations in a hospital at high concentrations (121 ppb). In general, high individual carbonyl levels as well as total carbonyls levels found in several locations indicated an unpropitious air quality for the occupants of these non-industrial sites.

Measurement of Organic Acids, Aldehydes, and Ketones in Residential Environments and Their Relation to Ozone

Ozone and several polar volatile organic compounds (VOCs) including organic acids and carbonyls (aldehydes and ketones) were measured over an approximately 24 hour period in four residences during the winter of 1993 and in nine residences during the summer of 1993. All residences were in the greater Boston, Massachusetts area. The relation of the polar VOCs to the ozone concentration was examined. Indoor carbonyl concentrations were similar between the summer and winter, with the total mean winter concentration being 31.7 ppb and the total mean summer concentration being 36.6 ppb. However, the average air exchange rate was 0.9 hr-1 during the winter and 2.6 hr-1 during the summer. Therefore, the estimated carbonyl emission rates were significantly higher during the summer. Indoor organic acid concentrations were about twice as high during the summer as during the winter. For formic acid, the indoor winter mean was 9.8 ppb, and the summer indoor mean was 17.8 ppb. For acetic acid, the indoor winter mean was 15.5 ppb, and the summer indoor mean was 28.7 ppb. The concentrations of the polar VOCs were found to be significantly correlated with one another. Also, the emission rates of the polar VOCs were found to be correlated with both the environmental variables such as temperature and relative humidity and the ozone removal rate; however, it was difficult to apportion the relative effects of the environmental variables and the ozone removal.