Methyl chloride and the U.S. cigarette.

Various brands and types of cigarettes were purchased at retail locations in southern California. Volatile gas samples were analyzed using multicolumn/multidetector gas chromatography. Results showed methyl chloride (CH(3)Cl) levels as much as four orders of magnitude higher than typical urban levels, about 30-500 ppmv (1.5-5.3 mg/cigarette), compared with about 500 pptv in urban air. The concentration of CH(3)Cl correlated well with the levels of both CO (r (2) = 0.63) and CO(2) (r (2) = 0.77), showing the link between CH(3)Cl and combustion. In some brands, CH(3)Cl levels were well above the U.S. Environmental Protection Agency's maximum exposure limit of 200 ppmv. Light branded cigarettes tended to have higher CH(3)Cl levels than the heavier and filtered brands, possibly showing the dependence of cigarette packing on CH(3)Cl production. In addition, CH(3)Cl emitted from cigarette smoke may prove to be an important anthropogenic source of CH(3)Cl in the United States, at about 5%

Bacteria in the airways of patients with cystic fibrosis are genetically capable of producing VOCs in breath.

Breath contains hundreds of volatile organic compounds (VOCs), the composition of which is altered in a wide variety of diseases. Bacteria are implicated in the formation of VOCs, but the biochemical mechanisms that lead to the formation of breath VOCs remain largely hypothetical. We hypothesized that bacterial DNA fragments in sputum of CF patients could be sequenced to identify whether the bacteria present were capable of producing VOCs found in the breath of these patients. Breath from seven patients with cystic fibrosis was sampled and analyzed by gas-chromatography and mass-spectrometry. Sputum samples were also collected and microbial DNA was isolated. Metagenomic sequencing was performed and the DNA fragments were compared to a reference database with genes that are linked to the metabolism of acetaldehyde, ethanol and methanol in the KEGG database. Bacteria in the genera Escherichia, Lactococcus, Pseudomonas, Rothia and Streptococcus were found to have the genetic potential to produce acetaldehyde and ethanol. Only DNA sequences from Lactococcus were implicated in the formation of acetaldehyde from acetate through aldehyde dehydrogenase family 9 member A1 (K00149). Escherichia was found to be genetically capable of producing ethanol in all patients, whilst there was considerable heterogeneity between patients for the other genera. The ethanol concentration in breath positively correlated with the amount of Escherichia found in sputum (Spearman rho  =  0.85,  P  =  0.015). Rothia showed the most versatile genetic potential for producing methanol. To conclude, bacterial DNA fragments in sputum of CF patients can be linked to enzymes implicated in the production of ethanol, acetaldehyde and methanol, which are VOCs that are predictive of respiratory tract colonization and/or infection. This supports that the lung microbiome can produce VOCs directly

Ambient mixing ratios of nonmethane hydrocarbons (NMHCs) in two major urban centers of the Pearl River Delta (PRD) region: Guangzhou and Dongguan

The Pearl River Delta (PRD) region can be considered one of the most economically developed areas of mainland China. In September 2005, a total of 96 whole air samples were collected in Guangzhou and Dongguan, two important urban centers of the PRD region. Guangzhou is considered the economic center of Guangdong province, and Dongguan is a rapidly expanding industrial city. Here, we report mixing ratios of 50 nonmethane hydrocarbons (NMHCs) that were quantified in the ambient air of these PRD centers. The discussion focuses on understanding the main sources responsible for NMHC emissions, and evaluating the role of the identified sources towards ozone formation. Propane was the most abundant species in Guangzhou, with an average mixing ratio of 6.8 ppbv (±0.7 ppbv S.E.), compared to 2.5±0.2 ppbv in Dongguan. Toluene was the most abundant hydrocarbon in Dongguan (6.1±0.8 ppbv, compared to 5.9±0.7 ppbv in Guangzhou). Based on an analysis of the correlation between vehicular-emitted compounds and the measured NMHCs, together with the benzene-to-toluene (B/T) ratio, vehicular emission appears to be the dominant source of NMHCs measured in Guangzhou. By contrast, selected species (including toluene) in many of the Dongguan samples were influenced by an additional source, most likely related to industrial activities. A specific B/T ratio (<0.20) is proposed here and used as indicator of samples strongly affected by industrial emissions. The ozone formation potential (OFP) is calculated, and the role of the different NMHCs associated with industrial and combustion sources is evaluated. © 2008 Elsevier Ltd. All rights reserved

Air quality in the Industrial Heartland of Alberta, Canada and potential impacts on human health.

The "Industrial Heartland" of Alberta is Canada's largest hydrocarbon processing center, with more than 40 major chemical, petrochemical, and oil and gas facilities. Emissions from these industries affect local air quality and human health. This paper characterizes ambient levels of 77 volatile organic compounds (VOCs) in the region using high-precision measurements collected in summer 2010. Remarkably strong enhancements of 43 VOCs were detected, and concentrations in the industrial plumes were often similar to or even higher than levels measured in some of the world's largest cities and industrial regions. For example maximum levels of propene and i-pentane exceeded 100 ppbv, and 1,3-butadiene, a known carcinogen, reached 27 ppbv. Major VOC sources included propene fractionation, diluent separation and bitumen processing. Emissions of the measured VOCs increased the hydroxyl radical reactivity (kOH), a measure of the potential to form downwind ozone, from 3.4 s-1 in background air to 62 s-1 in the most concentrated plumes. The plume value was comparable to polluted megacity values, and acetaldehyde, propene and 1,3-butadiene contributed over half of the plume kOH. Based on a 13-year record (1994-2006) at the county level, the incidence of male hematopoietic cancers (leukemia and non-Hodgkin lymphoma) was higher in communities closest to the Industrial Heartland compared to neighboring counties. While a causal association between these cancers and exposure to industrial emissions cannot be confirmed, this pattern and the elevated VOC levels warrant actions to reduce emissions of known carcinogens, including benzene and 1,3-butadiene

Secondary organic aerosol formation from in-use motor vehicle emissions using a potential aerosol mass reactor.

Secondary organic aerosol (SOA) formation from in-use vehicle emissions was investigated using a potential aerosol mass (PAM) flow reactor deployed in a highway tunnel in Pittsburgh, Pennsylvania. Experiments consisted of passing exhaust-dominated tunnel air through a PAM reactor over integrated hydroxyl radical (OH) exposures ranging from ∼ 0.3 to 9.3 days of equivalent atmospheric oxidation. Experiments were performed during heavy traffic periods when the fleet was at least 80% light-duty gasoline vehicles on a fuel-consumption basis. The peak SOA production occurred after 2-3 days of equivalent atmospheric oxidation. Additional OH exposure decreased the SOA production presumably due to a shift from functionalization to fragmentation dominated reaction mechanisms. Photo-oxidation also produced substantial ammonium nitrate, often exceeding the mass of SOA. Analysis with an SOA model highlight that unspeciated organics (i.e., unresolved complex mixture) are a very important class of precursors and that multigenerational processing of both gases and particles is important at longer time scales. The chemical evolution of the organic aerosol inside the PAM reactor appears to be similar to that observed in the atmosphere. The mass spectrum of the unoxidized primary organic aerosol closely resembles ambient hydrocarbon-like organic aerosol (HOA). After aging the exhaust equivalent to a few hours of atmospheric oxidation, the organic aerosol most closely resembles semivolatile oxygenated organic aerosol (SV-OOA) and then low-volatility organic aerosol (LV-OOA) at higher OH exposures. Scaling the data suggests that mobile sources contribute ∼ 2.9 ± 1.6 Tg SOA yr(-1) in the United States, which is a factor of 6 greater than all mobile source particulate matter emissions reported by the National Emissions Inventory. This highlights the important contribution of SOA formation from vehicle exhaust to ambient particulate matter concentrations in urban areas