Atmospheric Formaldehyde Research Articles

Sensitivity of Ambient Atmospheric Formaldehyde and Ozone to Precursor Species and Source Types Across the United States.

Formaldehyde (HCHO) is an important air pollutant from both an atmospheric chemistry and human health standpoint. This study uses an instrumented photochemical Air Quality Model, CMAQ-DDM, to identify the sensitivity of HCHO concentrations across the United States (U.S.) to major source types and hydrocarbon speciation. In July, biogenic sources of hydrocarbons contribute the most (92% of total hydrocarbon sensitivity), split between isoprene and other alkenes. Among anthropogenic sources, mobile sources of hydrocarbons and nitrogen oxides (NO x) dominate. In January, HCHO is more sensitive to anthropogenic hydrocarbons than biogenic sources, especially mobile sources and residential wood combustion (36% of national hydrocarbon sensitivity). While ozone (O3) is three times more sensitive to NO x than hydrocarbons across most areas of the U.S., HCHO is six times more sensitive to hydrocarbons than NO x, largely due to sensitivity to biogenic precursors and the importance of low-NO x chemistry. In winter, both HCHO and O3 show negative sensitivity to NO x (increases with the removal of NO x), although O3 increases are larger. Relative sensitivities do not change substantially across different regions of the country.

Development of an innovative gas chromatography-mass spectrometry method for assessment of formaldehyde in the workplace atmosphere

World consumption of formaldehyde (FA) is forecast to grow at an average annual rate of about 4% from 2015 to 2020 with world production to exceed 52 million tons in 2017. From the first day of January 2016, the Commission Regulation No. 91/2015 established the FA classification through an indication from European Chemical Agency as category 2 mutagenic and category 1B carcinogen. A novel method for the determination of gaseous FA in air is presented herewith. The sampling was carried out using a miniaturized cartridge by means of a medium-flow pumping system (1.0 L min-1, 5–60 min) and absorption of FA vapors on 2,4-dinitrophenylhydrazine. Cartridge desorption removing the excess derivatizing agent based upon solid-phase extraction was performed by an innovative xyz robotic system on-line with fast gas chromatography (GC)—mass spectrometry (MS). Through the generation of standard atmospheres of known concentration of FA, we evaluated the precision (relative standard deviation for n = 10, 8.8%), lower limit of quantification (0.072 µg/cartridge), and linearity (from 0.125—64 µg/cartridge with correlation coefficient of 0.99) of the method. The described procedure combines the efficiency of fast GC—MS systems with both the high throughput of autosampler and the quantitative accuracy of FA-dinitrophenylhydrazone for measuring American Conference of Governmental Industrial Hygienists TLV Ceiling.

Sources and Potential Photochemical Roles of Formaldehyde in an Urban Atmosphere in South China

AbstractFormaldehyde (HCHO) is an important intermediate in tropospheric photochemistry. However, study of its evolution characteristics under heavy pollution conditions in China is limited, especially for high temporal resolutions, making it difficult to analyze its sources and environmental impacts. In this study, ambient levels of HCHO were monitored using a proton‐transfer reaction mass spectrometer at an urban site in the Pearl River Delta of China. Continuous monitoring campaigns were conducted in the spring, summer, fall, and winter in 2016. The highest averaged HCHO concentrations were observed in autumn (5.1 ± 3.1 ppbv) and summer (5.0 ± 4.4 ppbv), followed by winter (4.2 ± 2.2 ppbv) and spring (3.4 ± 1.6 ppbv). The daily maximum of HCHO occurs in the early afternoon and shows good correlations with O3 and the secondary organic aerosol tracer during the day, revealing close relationships between ambient HCHO and secondary formations in Shenzhen, especially in summer and autumn. The daytime HCHO is estimated to be the major contributor to O3 formation and OH radical production, indicating that HCHO plays a key role in the urban atmospheric photochemical reactions. Anthropogenic secondary formation was calculated to be the dominant source of HCHO using a photochemical age‐based parameterization method, with an average proportion of 39%. The contributions of biogenic sources in summer (41%) and autumn (39%) are much higher than those in spring (26%) and winter (28%), while the contributions of anthropogenic primary sources in spring (20%) and winter (18%) are twice those in summer (9%) and autumn (9%).

Drought impacts on photosynthesis, isoprene emission and atmospheric formaldehyde in a mid-latitude forest

Isoprene plays a critical role in air quality and climate. Photosynthesis (gross primary productivity, GPP) and formaldehyde (HCHO) are both related to isoprene emission at large spatiotemporal scales, but neither is a perfect proxy. We apply multiple satellite products and site-level measurements to examine the impact of water deficit on the three interlinked variables at the Missouri Ozarks site during a 20-day mild dryness stress in summer 2011 and a 3-month severe drought in summer 2012. Isoprene emission shows opposite responses to the short- and long-term droughts, while GPP was substantially reduced in both cases. In 2012, both remote-sensed solar-induced fluorescence (SIF) and satellite HCHO column qualitatively capture reductions in flux-derived GPP and isoprene emission, respectively, on weekly to monthly time scales, but with muted responses. For instance, as flux-derived GPP approaches zero in late summer 2012, SIF drops by 29–33% (July) and 19–27% (August) relative to year 2011. A possible explanation is that electron transport and photosystem activity are maintained to a certain extent under the drought stress. Similarly, flux tower isoprene emissions in July 2012 are 54% lower than July 2011, while the relative reductions in July for 3 independent satellite-derived HCHO data products are 27%, 12% and 6%, respectively. We attribute the muted HCHO response to a photochemical feedback whereby reduced isoprene emission increases the oxidation capacity available to generate HCHO from other volatile organic compound sources. Satellite SIF offers a potential alternative indirect method to monitor isoprene variability at large spatiotemporal scales from space, although further research is needed under different environmental conditions and regions. Our analysis indicates that fairly moderate reductions in satellite SIF and HCHO column may imply severe drought conditions at the surface.

High temperature reduction dramatically promotes Pd/TiO2 catalyst for ambient formaldehyde oxidation

High temperature reduction generally induces the sintering of supported noble metals, therefore resulting in a negative effect on their performance. Here, we show that high temperature reduction was able to dramatically increase the activity of Pd/TiO2 for ambient HCHO oxidation. We prepared a Pd/TiO2 catalyst and pre-reduced it with H2 at low temperature (300°C) and high temperature (450°C), respectively, and then tested the activity for HCHO oxidation at ambient temperature. The Pd/TiO2-450R catalyst showed a much better performance than Pd/TiO2-300R at room temperature. 100% HCHO conversion could be obtained on the Pd/TiO2-450R catalyst at a GHSV of 95000h−1 and 140ppm inlet HCHO. The catalysts were then characterized by using Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), High-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) and other methods. The results indicate that high temperature reduction could induce the strong metal-support interaction (SMSI), decreasing the surface Pd particle size by partially encapsulating and trapping Pd clusters with TiO2, and also could produce more oxygen vacancies, beneficial to the activation of O2 and formation of surface OH groups, opening a more effective pathway for ambient HCHO oxidation. Therefore, the Pd/TiO2-450R catalyst demonstrated high activity for ambient HCHO oxidation.

Observing atmospheric formaldehyde (HCHO) from space: validation and intercomparison of six retrievals from four satellites (OMI, GOME2A, GOME2B, OMPS) with SEAC4RS aircraft observations over the Southeast US.

Formaldehyde (HCHO) column data from satellites are widely used as a proxy for emissions of volatile organic compounds (VOCs) but validation of the data has been extremely limited. Here we use highly accurate HCHO aircraft observations from the NASA SEAC4RS campaign over the Southeast US in August-September 2013 to validate and intercompare six retrievals of HCHO columns from four different satellite instruments (OMI, GOME2A, GOME2B and OMPS) and three different research groups. The GEOS-Chem chemical transport model is used as a common intercomparison platform. All retrievals feature a HCHO maximum over Arkansas and Louisiana, consistent with the aircraft observations and reflecting high emissions of biogenic isoprene. The retrievals are also interconsistent in their spatial variability over the Southeast US (r=0.4-0.8 on a 0.5°×0.5° grid) and in their day-to-day variability (r=0.5-0.8). However, all retrievals are biased low in the mean by 20-51%, which would lead to corresponding bias in estimates of isoprene emissions from the satellite data. The smallest bias is for OMI-BIRA, which has high corrected slant columns relative to the other retrievals and low scattering weights in its air mass factor (AMF) calculation. OMI-BIRA has systematic error in its assumed vertical HCHO shape profiles for the AMF calculation and correcting this would eliminate its bias relative to the SEAC4RS data. Our results support the use of satellite HCHO data as a quantitative proxy for isoprene emission after correction of the low mean bias. There is no evident pattern in the bias, suggesting that a uniform correction factor may be applied to the data until better understanding is achieved.

Про можливі механізми впливу атмосферних забруднень формальдегідом на формування захворюваності населення на рак щитоподібної залози

Про можливі механізми впливу атмосферних забруднень формальдегідом на формування захворюваності населення на рак щитоподібної залози

Diurnal cycle and multi-decadal trend of formaldehyde in the remote atmosphere near 46° N

Abstract. Only very few long-term records of formaldehyde (HCHO) exist that are suitable for trend analysis. Furthermore, many uncertainties remain as to its diurnal cycle, representing a large short-term variability superimposed on seasonal and inter-annual variations that should be accounted for when comparing ground-based observations to, e.g., model results. In this study, we derive a multi-decadal time series (January 1988–June 2015) of HCHO total columns from ground-based high-resolution Fourier transform infrared (FTIR) solar spectra recorded at the high-altitude station of Jungfraujoch (Swiss Alps, 46.5° N, 8.0° E, 3580 m a. s. l. ), allowing for the characterization of the mid-latitudinal atmosphere for background conditions. First we investigate the HCHO diurnal variation, peaking around noontime and mainly driven by the intra-day insolation modulation and methane (CH4) oxidation. We also characterize quantitatively the diurnal cycles by adjusting a parametric model to the observations, which links the daytime to the HCHO columns according to the monthly intra-day regimes. It is then employed to scale all the individual FTIR measurements on a given daytime in order to remove the effect of the intra-day modulation for improving the trend determination and the comparison with HCHO columns simulated by the state-of-the-art GEOS-Chem v9-02 chemical transport model. Such a parametric model will be useful to scale the Jungfraujoch HCHO columns on satellite overpass times in the framework of future calibration/validation efforts of space-borne sensors. GEOS-Chem sensitivity tests suggest then that the seasonal and inter-annual HCHO column variations above Jungfraujoch are predominantly led by the atmospheric CH4 oxidation, with a maximum contribution of 25 % from the anthropogenic non-methane volatile organic compound precursors during wintertime. Finally, trend analysis of the so-scaled 27-year FTIR time series reveals a long-term evolution of the HCHO columns in the remote troposphere to be related to the atmospheric CH4 fluctuations and the short-term OH variability: +2.9 % year−1 between 1988 and 1995, −3.7 % year−1 over 1996–2002 and +0.8 % year−1 from 2003 onwards.

Respiratory protection for firefighters—Evaluation of CBRN canisters for use during overhaul II: In mask analyte sampling with integrated dynamic breathing machine

ABSTRACTAccording to the National Fire Protection Association there were 487,500 structural fires in the U.S. in 2013. After visible flames are extinguished firefighters begin the overhaul stage where remaining hot spots are identified and further extinguished. During overhaul, a significant amount of potentially hazardous chemicals can remain in the ambient environment. Previous research suggests that the use of air purifying respirators fitted with chemical, biological, radiological, and nuclear (CBRN) canisters may reduce occupational exposure. This study used large scale burns of representative structural materials to perform side-by-side, filtering, and service-life evaluations of commercially available CBRN filters using two head forms fitted with full-face respirators and a dynamic breathing machine. Three types of CBRN canisters and one non-CBRN cartridge were challenged in repetitive post-fire environments. Tests were conducted with two different breathing volumes and rates for two sampling durations (0–15 min and 0–60 min). Fifty-five different chemicals were selected for evaluation and results indicate that 10 of the 55 chemicals were present in the post-fire overhaul ambient environment. Acetaldehyde and formaldehyde were found to be the only two chemicals detected post filter but were effectively filtered to below ACGIH TLVs. Counter to our prior published work using continuous flow filter evaluation, this study indicates that, regardless of brand, CBRN filters were effective at reducing concentrations of post-fire ambient chemicals to below occupational exposure limits. However, caution should be applied when using CBRN filters as the ambient formaldehyde level in the current study was 8.9 times lower than during the previous work.

Injection Seeded Laser for Formaldehyde Differential Fluorescence Lidar

We describe the design and development of an injection seeded Nd:YVO4 laser for use in a differential fluorescence lidar for measuring atmospheric formaldehyde profiles. A high repetition rate Q-switched laser is modified to accept injection seed input to spectrally narrow and tune the output. The third harmonic output is used to excite formaldehyde (HCHO) fluorescence when tuned to a HCHO absorption line. Spectral confirmation is made with the use of a photoacoustic cell and grating spectrometer.

Analysis of ambient formaldehyde in the eastern region of India along Indo-Gangetic Plain.

Ambient levels of formaldehyde (HCHO) were measured in the tropical urban mega city of Kolkata from July 2012 to April 2014, based on USEPA Compendium Method TO-11A using 2,4-dinitrophenylhydrazine (2,4-DNPH). The samples were analyzed by isocratic reverse-phase high-performance liquid chromatography (HPLC) with an ultraviolet detector at a wavelength of 360 nm. High values of HCHO were recorded at our site. The highest and average HCHO mixing ratio measured for the entire study period was 803 and 217 ppbv respectively. Seasonal wind regimes have been found to influence the seasonal pattern of HCHO mixing ratio at this site resulting in relatively higher mixing ratio of HCHO during the pre-monsoon periods as compared to the others. Apart from these, sampling-based measurements of CH4 and continuous measurements of ozone (O3) and CO were also performed with the objective to study the interrelationship of HCHO with these species. The results suggest the presence of highly complex chemistry among them.

Quantifying the ambient formaldehyde sources utilizing tracers

Abstract Formaldehyde (HCHO) is one of the most important intermediate products of atmospheric photochemical reactions in the troposphere, therefore understanding of HCHO sources is essential for effective ozone control measures. The objective of this work is to distinguish between primary and secondary sources of HCHO. Based on about one month of online measurements in winter in Ziyang, Sichuan, the multi-linear regression analysis of ambient concentrations of HCHO and possible tracers (acetonitrile, propane and peroxyacetyl nitrate) was performed. The results show that during winter in Ziyang, biomass burning contributed an average of 53.2% to ambient HCHO levels, while secondary processes contributed about 30.1%, and vehicular sources accounted for 7.1%.

Formaldehyde and acetaldehyde measurements in urban atmosphere impacted by the use of ethanol biofuel: Metropolitan Area of Sao Paulo (MASP), 2012–2013

There is a consensus that particulate matter and gases pollutants originating from industry and vehicle emission processes in urban areas are important from the point of view of public health and climate change. Local anthropogenic emissions, especially those resulting from energy generation processes from the industrial and transport sector, are connected with those occurring at the regional and global scales. A major concern in the Metropolitan Area of São Paulo (MASP) is the impact of the large scale use of ethanol as a fuel and as an additive for Otto vehicles. In this study, atmospheric concentrations of ozone, nitrogen oxides (NO and NO2), formaldehyde and acetaldehyde were measured in the MASP in Brazil, over four seasons in 2012 and 2013. The results were compared with data collected in previous studies. Our results demonstrate that, although there was a large increase in the number of vehicles in the MASP that use ethanol (“flex-fuel” vehicles), technological advances in vehicle emissions control have prevented any significant increase in the atmospheric concentrations of aldehydes. In addition, an increase in the formaldehyde/acetaldehyde ratio has been observed.

Understanding primary and secondary sources of ambient carbonyl compounds in Beijing using the PMF model

Abstract. Carbonyl compounds are important intermediates in atmospheric photochemistry. To explore the relative contributions of primary and secondary carbonyl sources, carbonyls and other volatile organic compounds (VOCs) were measured at an urban site in both winter and summer in Beijing. The positive matrix factorization (PMF) model was used for source apportionment of VOCs. As VOCs undergo photochemical processes in the atmosphere, and such processes may interfere with factor identification, the relationships between the contributions of the resolved PMF factors to each non-methane hydrocarbon (NMHC) species and its kOH value were used to distinguish fresh factors and photochemically aged factors. As the result of PMF, five factors were resolved in winter, and two of them were identified as photochemically aged emissions. In summer, four factors were resolved, including one aged factor. Carbonyls abundances from aged factors were simulated by VOCs consumption and the corresponding carbonyl production yields, and the simulated abundances agreed well with the results obtained by the PMF model. The source apportionment results indicated that secondary formation was the major source of carbonyls in both winter and summer, with the respective contributions of 51.2% and 46.0%. For the three major carbonyl species, primary anthropogenic sources contributed 28.9% and 32.3% to ambient formaldehyde, 53.7% and 41.6% to acetaldehyde, 68.1% and 56.2% to acetone in winter and summer, respectively.

Urban atmospheric formaldehyde concentrations measured by a differential optical absorption spectroscopy method

In this study a differential optical absorption spectroscopy (DOAS) method was used to monitor formaldehyde (HCHO) concentrations in Shanghai ambient air at a research station in Fudan University. The measurements were carried out during April 2010-April 2011 and a total of 120 940 recorded data points were obtained. The average HCHO concentration was found to be the highest (10.0 ppbv) during August 2010 and the lowest (2.0 ppbv) during April 2010. The diurnal variation of HCHO and O3 followed very similar trends in all the seasons. This was evident from the fact that HCHO had a strong positive correlation with O3. Both peaked once in the morning (07:00-09:00 local time), and once in the night (16:00-19:00 local time). The peak concentrations varied from season to season, which could be attributed to the seasonal variation in anthropogenic activity, traffic movement and atmospheric boundary layer conditions. The background HCHO concentration in 2011 winter (similar to 12.0 ppbv) was an order of magnitude higher than that observed in 2010 spring (similar to 2.0 ppbv); corresponding with the results of several pollution controls adopted by the Shanghai administrative government before and after the EXPO 2010 period (May 1, 2010-Oct. 31 2010). This study contributed the basic information for understanding the concentration level and the chemical processes of atmospheric HCHO in a major metropolitan area.

Formaldehyde in the ambient atmosphere - from an indoor pollutant to an outdoor pollutant?

Formaldehyde has been discussed as a typical indoor pollutant for decades. Legal requirements and ever-lower limits for formaldehyde in indoor air have led to a continual reduction in the amount of formaldehyde released from furniture, building materials, and household products over many years. Slowly, and without much attention from research on indoor air, a change of paradigm is taking place, however. Today, the formaldehyde concentrations in outdoor air, particularly in polluted urban areas, sometimes already reach indoor levels. This is largely a result of photochemical processes and the use of biofuels. In the medium term, this development might have consequences for the way buildings are ventilated and lead to a change in the way we evaluate human exposure.

ChemInform Abstract: Formaldehyde in the Ambient Atmosphere: From an Indoor Pollutant to an Outdoor Pollutant?

AbstractReview: about 80 refs.

Formaldehyde in the Ambient Atmosphere: From an Indoor Pollutant to an Outdoor Pollutant?

Formaldehyde has been discussed as a typical indoor pollutant for decades. Legal requirements and ever-lower limits for formaldehyde in indoor air have led to a continual reduction in the amount of formaldehyde released from furniture, building materials, and household products over many years. Slowly, and without much attention from research on indoor air, a change of paradigm is taking place, however. Today, the formaldehyde concentrations in outdoor air, particularly in polluted urban areas, sometimes already reach indoor levels. This is largely a result of photochemical processes and the use of biofuels. In the medium term, this development might have consequences for the way buildings are ventilated and lead to a change in the way we evaluate human exposure.

Measurements of formaldehyde at the U.S.–Mexico border during the Cal-Mex 2010 air quality study

Ambient formaldehyde (HCHO), along with other volatile organic compounds (VOCs), was measured using proton-transfer reaction mass spectrometry (PTR-MS) at a ground site along the U.S.–Mexico border during the Cal-Mex 2010 air quality study. During the observation period, the HCHO mixing ratio varied between 1.0 ppbv and 13.7 ppbv. On average, a daily maximum of 6.3 ± 2.6 ppbv occurred around 10 AM and a minimum of 2.8 ± 1.3 ppbv was observed around midnight. The early onset of the HCHO daily maximum (∼ 3 h before the solar noon) indicated the presence of primary HCHO sources and a fast photolysis loss of HCHO, consistent with a measured low ratio of HCHO to acetaldehyde of (2.5 ± 0.8). Using the simulated photolysis rates, we estimated the contribution of OH radical production from HCHO photolysis relative to that from O3 photolysis, with a ratio from 0.8 to 18 and the highest values around traffic rush hours. Hence, our results indicate that HCHO plays a dominant role in regulating the OH radical budget in the area.

13C isotope evidence for photochemical production of atmospheric formaldehyde, acetaldehyde, and acetone pollutants in Guangzhou

Ambient formaldehyde, acetaldehyde, and acetone are harmful air pollutants with potential carcinogenic effects on human health. They are considered as important photochemical products from photo-oxidation of atmospheric hydrocarbons. However, little is known on the effet of photodegradation of air pollutants on δ13C values. Here, we report the first 13C isotope evidence for the photochemical production of ambient formaldehyde, acetaldehyde, and acetone. Air samples were collected each day during early morning, noon, early afternoon, and late afternoon on 17–19 September 2008 in Guangzhou by drawing air through 2,4-dinitrophenylhydrazine-coated cartridges. The samples were analyzed using high-performance liquid chromatography for concentration analysis and then using gas chromatography-combustion-isotope ratio mass spectrometry for δ13C analysis. Our results show that ambient formaldehyde, acetaldehyde, and acetone were enriched by 1–5 ‰ in 13C in the early afternoon relative to other sampling durations, and they also exhibited the highest concentrations in the early afternoon. Measured δ13C values of formaldehyde, acetaldehyde, and acetone were in the range from −37.15 to −29.01 ‰. The observed enrichment in 13C implied important photochemical production together with the highest concentrations in the early afternoon. Especially, measured δ13C range from −37.15 to −29.01 ‰ was in accordance with forecasted δ13C range from −43 to −28 ‰ based on the mass balance in 13C between the carbonyls and its major hydrocarbon precursors, providing important 13C isotope evidence for the photochemical production of ambient formaldehyde, acetaldehyde, and acetone.