Polycyclic aromatic hydrocarbon burden in ambient air in selected Niger Delta communities in Nigeria

Assessing the chemical composition, potential toxicity and cancer risk of airborne fine particulate matter (PM2.5) near a petrochemical industrial area

In the vicinity of a petrochemical industrial region in São Paulo, Brazil, PM_2.5-bound organic carbon (OC), elemental carbon (EC), polycyclic aromatic hydrocarbons (PAHs), nitro-PAHs, oxy-PAHs, hopanes, and inorganic species were evaluated. Oxidative potential (OP), burden (OB), and Alivibrio fischeri bioluminescence inhibition (AFBIA) assays were conducted to determine the potential health effects of exposure to these compounds. The PM_2.5 mean concentration was 32.0±18.2µgm^-3, and benzo (a)pyrene was found to exceed recommended levels by at least four times. Secondary sources and vehicular emissions were indicated by nitro-PAHs, oxy-PAHs, and inorganic species. The OP and OB results revealed that secondary compounds favored antioxidant depletion. The AFBIA results showed that 64% of the samples were toxic. These findings emphasize the need to reduce the exposure risk and take measures to protect human health.

Exposure to Particulate PAHs on Potential Genotoxicity and Cancer Risk among School Children Living Near the Petrochemical Industry

This study aimed to assess the association of exposure to particle-bound (PM_2.5) polycyclic aromatic hydrocarbons (PAHs) with potential genotoxicity and cancer risk among children living near the petrochemical industry and comparative populations in Malaysia. PM_2.5 samples were collected using a low-volume sampler for 24 h at three primary schools located within 5 km of the industrial area and three comparative schools more than 20 km away from any industrial activity. A gas chromatography-mass spectrometer was used to determine the analysis of 16 United States Environmental Protection Agency (USEPA) priority PAHs. A total of 205 children were randomly selected to assess the DNA damage in buccal cells, employing the comet assay. Total PAHs measured in exposed and comparative schools varied, respectively, from 61.60 to 64.64 ng m^-3 and from 5.93 to 35.06 ng m^-3. The PAH emission in exposed schools was contributed mainly by traffic and industrial emissions, dependent on the source apportionment. The 95th percentiles of the incremental lifetime cancer risk estimated using Monte Carlo simulation revealed that the inhalation risk for the exposed children and comparative populations was 2.22 × 10^-6 and 2.95 × 10^-7, respectively. The degree of DNA injury was substantially more severe among the exposed children relative to the comparative community. This study reveals that higher exposure to PAHs increases the risk of genotoxic effects and cancer among children.

Dispersion of gas flaring emissions in the Niger delta: Impact of prevailing meteorological conditions and flare characteristics

An understanding of the dispersion and level of emissions source of atmospheric pollutants; whether point, area or volume sources, is required to inform policies on air pollution and day-to-day predictions of pollution level. Very few studies have carried out simulations of the dispersion pattern and ground-level concentration of pollutants emitted from real-world gas flares. The limited availability of official data on gas flares from the oil and gas industries makes accurate dispersion calculations difficult. Using ADMS 5 and AERMOD, this study assessed the sensitivity of dispersion and ground-level concentration of pollutants from gas flares in the Niger Delta to prevailing meteorological condition; fuel composition; and flare size. Although, during the non-WAM (West African Monsoon) months (November and March), the simulated ground-level concentrations of pollutants from a single flare are lower, the dispersion of pollutants is towards both the inland and coastal communities. In the WAM months, the ground-level concentrations are higher and are dispersed predominantly over the inland communities. Less buoyant plumes from smaller flares (lower volume flow rates) and/or flaring of fuel with lower heat content results in higher ground-level concentrations in areas closer to the flare. Considering the huge number of flares scattered around the region, a mitigation of the acute local pollution level would be to combine short stacks flaring at lower volume flow rates to enhance the volume flow rate of a single exhaust, and hence, the buoyancy of the plume exiting the stack.

Environmental and individual PAH exposures near rural natural gas extraction

Natural gas extraction (NGE) has expanded rapidly in the United States in recent years. Despite concerns, there is little information about the effects of NGE on air quality or personal exposures of people living or working nearby. Recent research suggests NGE emits polycyclic aromatic hydrocarbons (PAHs) into air. This study used low-density polyethylene passive samplers to measure concentrations of PAHs in air near active (n = 3) and proposed (n = 2) NGE sites. At each site, two concentric rings of air samplers were placed around the active or proposed well pad location. Silicone wristbands were used to assess personal PAH exposures of participants (n = 19) living or working near the sampling sites. All samples were analyzed for 62 PAHs using GC-MS/MS, and point sources were estimated using the fluoranthene/pyrene isomer ratio. ∑PAH was significantly higher in air at active NGE sites (Wilcoxon rank sum test, p < 0.01). PAHs in air were also more petrogenic (petroleum-derived) at active NGE sites. This suggests that PAH mixtures at active NGE sites may have been affected by direct emissions from petroleum sources at these sites. ∑PAH was also significantly higher in wristbands from participants who had active NGE wells on their properties than from participants who did not (Wilcoxon rank sum test, p < 0.005). There was a significant positive correlation between ∑PAH in participants' wristbands and ∑PAH in air measured closest to participants' homes or workplaces (simple linear regression, p < 0.0001). These findings suggest that living or working near an active NGE well may increase personal PAH exposure. This work also supports the utility of the silicone wristband to assess personal PAH exposure.

In vitro and in vivo investigation of the genotoxic potential of waters from rivers under the influence of a petroleum refinery (São Paulo State - Brazil)

In recent years concern about the chemical composition of wastewater generated by the oil refining industry has increased, even after its treatment. These wastewaters contain substances that can harm both the entire aquatic ecosystem and the health of any exposed organisms. The aim of this study was to evaluate the genotoxic and mutagenic potentials of the effluent generated by the largest Brazilian petroleum refinery, the effectiveness of the treatments used by the refinery, and whether its effluent can compromise the water quality of the river where it is discarded. Chromosomal aberration and micronucleus assays were performed in Allium cepa and micronucleus test in mammalian cell culture (CHO-K1). The samples were collected in three sites at the refinery: one site on the Jaguari River and two sites on the Atibaia Rivers (upstream and downstream of the discharged effluent), under three different climatic conditions. Tests with A. cepa showed increased frequencies of chromosomal aberrations and micronuclei in meristematic cells for the effluent after physico-chemical treatment, but the samples after treatment biological and stabilization pond presented none of these abnormalities. It was observed that the induced damage in the meristematic cells was not observed in the F₁ cells of A. cepa roots. The micronucleus test performed with mammalian cell culture also indicated that the effluent, after physico-chemical treatment, induced a significant increase in micronucleus frequencies. Plant and hamster cells exposed to the other samples collected inside the refinery and in the Jaguari and Atibaia Rivers did not present evidence of genotoxicity and mutagenicity in the tests performed. This study showed that the effluent treated carried out by the refinery (biological treatment followed by a stabilization pond) proved to be efficient for the removal of the toxic load still present after the physico-chemical treatment, since no change in the quality of the Atibaia River was observed. However, because this is an industry with a high production of effluent with toxic potential, its effluents must be constantly monitored, so that there is no compromise of the water quality of the receiving river.

Air Quality Impact of Diffuse and Inefficient Combustion Emissions in Africa (DICE-Africa)

Anthropogenic pollution in Africa is dominated by diffuse and inefficient combustion sources, as electricity access is low and motorcycles and outdated cars proliferate. These sources are missing, out-of-date, or misrepresented in state-of-the-science emission inventories. We address these deficiencies with a detailed inventory of Diffuse and Inefficient Combustion Emissions in Africa (DICE-Africa) for 2006 and 2013. Fuelwood for energy is the largest emission source in DICE-Africa, but grows from 2006 to 2013 at a slower rate than charcoal production and use, and gasoline and diesel for motorcycles, cars, and generators. Only kerosene use and gas flaring decline. Increase in emissions from 2006 to 2013 in this work is consistent with trends in satellite observations of formaldehyde and NO₂, but much slower than the explosive growth projected with a fuel consumption model. Seasonal biomass burning is considered a large pollution source in Africa, but we estimate comparable emissions of black carbon and higher emissions of nonmethane volatile organic compounds from DICE-Africa. Nitrogen oxide (NO_x ≡ NO + NO₂) emissions are much lower than from biomass burning. We use GEOS-Chem to estimate that the largest contribution of DICE-Africa to annual mean surface fine particulate matter (PM_2.5) is >5 μg m^-3 in populous Nigeria.

Gas flaring and resultant air pollution: A review focusing on black carbon

Gas flaring is a prominent source of VOCs, CO, CO2, SO2, PAH, NOX and soot (black carbon), all of which are important pollutants which interact, directly and indirectly, in the Earth's climatic processes. Globally, over 130 billion cubic metres of gas are flared annually. We review the contribution of gas flaring to air pollution on local, regional and global scales, with special emphasis on black carbon (BC, "soot"). The temporal and spatial characteristics of gas flaring distinguishes it from mobile combustion sources (transport), while the open-flame nature of gas flaring distinguishes it from industrial point-sources; the high temperature, flame control, and spatial compactness distinguishes gas flaring from both biomass burning and domestic fuel-use. All of these distinguishing factors influence the quantity and characteristics of BC production from gas flaring, so that it is important to consider this source separately in emissions inventories and environmental field studies. Estimate of the yield of pollutants from gas flaring have, to date, paid little or no attention to the emission of BC with the assumption often being made that flaring produces a smokeless flame. In gas flares, soot yield is known to depend on a number of factors, and there is a need to develop emission estimates and modelling frameworks that take these factors into consideration. Hence, emission inventories, especially of the soot yield from gas flaring should give adequate consideration to the variation of fuel gas composition, and to combustion characteristics, which are strong determinants of the nature and quantity of pollutants emitted. The buoyant nature of gas flaring plume, often at temperatures in the range of 2000 K, coupled with the height of the stack enables some of the pollutants to escape further into the free troposphere aiding their long-range transport, which is often not well-captured by model studies.

Assessment of the levels of urinary 1-hydroxypyrene and air polycyclic aromatic hydrocarbon in PM2.5 for adult exposure to the petrochemical complex emissions

The relationship between external exposure and internal doses of polycyclic aromatic hydrocarbons (PAHs) has not been established for people living in industrial areas. This study was carried out to estimate the relationship between particle-phase PAH exposure and urinary 1-hydroxypyrene (1-OHP) levels among the adults living near a large petrochemical complex in Mailiao, Taiwan. We measured urinary 1-OHP in 781 residents above 35 years old and PM2.5 PAHs within a 20-km radius downwind from the petrochemical complex. Urinary 1-OHP was analyzed by high performance liquid chromatography, while 16 ambient particle-phase PAHs were measured by gas chromatography mass spectrometry. External exposures to individual PAHs at each study subject's address were estimated by kriging interpolation from air sampling results and regressed against the subjects' urinary 1-OHP levels, adjusting for confounding factors. The study population's urinary 1-OHP levels ranged from 0.001 to 3.005 μmol/mol-creatinine with significantly higher levels for females, grilled food consumers, and residents living close to roads. All 16 particle-phase PAHs were present in the study area with total PAH concentrations ranging from 0.111 to 1.982 ng/m(3). The spatial distribution of 4- and 5-ring PAHs identified high-concentration hotspots close to the complex in Mailiao. The multiple regression models showed that the adults' urinary 1-OHP levels were significantly correlated with 5 out of the 16 PAHs, including benzo[a]anthracene, benzo[k]fluoranthene, fluoranthene, pyrene, and dibenzo[a,h]anthracene; a 0.01 ng/m(3) increase in the concentration of these 5 PAHs at the study subjects' addresses was associated with a 20% elevation in urinary 1-OHP levels (μg/g-creatinine). Emissions from a petrochemical complex can elevate particle-phase PAH concentrations in surrounding areas and increase the urinary 1-OHP levels of adults living nearby.