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This study investigated the contribution of anthropogenic emission of benzene from petroleum refineries to the Nigerian’s ambient air quality with the view of understanding the impact of petroleum production facilities on host airshed. The Activities of the four existing and 22 proposed petroleum refineries in Nigeria were obtained from the Department of Petroleum Resources and these were combined with emission factors of different units at the refineries to estimate benzene emissions. No-control-measure option (worst case scenario) was assumed because of lack of information on control efficiency of the refineries. The study revealed that two of the existing refineries in one of the oil-producing cities in Nigeria released a total of 10.01 × 1011 tons/year of benzene into the ambient air of the city, apart from additional 2.35 × 1013 tons/year anticipated to be released from three of the proposed refineries into the ambient air of the same host community. If operated at full capacity, the estimated benzene emission from the four existing refineries stood at 5.50 × 1013 tons/year while the 22 proposed refineries have the capacity of releasing additional 16.73 × 1013 ton/year. On the overall, the contribution of benzene from refineries on yearly basis to Nigerian airshed was estimated to be 22.24 × 1013 tons. These concentrations if not checked could lead to devastating environmental issues. Some mitigating measures were suggested to control and subsequently abate benzene emission from these refineries.

Environmental hazards associated with release of emission from petroleum refineries have caused serious concerns for the host communities. The study focused on the assessment of the contribution of Nigerian refineries to the ambient air quality. Total emission of toluene, ethyl benzene and xylene (TEX) from Nigerian twenty-six (four existing and twenty-two proposed) refineries were estimated using emission factor approach, under no-control measure (worst case scenario) option. Results showed that the four existing refineries emit 2.90 × 1013 tons of toluene, 1.93 × 1013 tons ethyl benzene and 1.06 × 1013 tons per year while the twenty-two proposed refineries have the capacity of releasing annually 9.17 × 1013 tons of toluene, 6.69 × 1013 tons of ethyl benzene and .95 x 1013 tons of xylene. If operated at full capacity, the total estimated TEX emission from the existing refineries stood at 5.89 × 1013 tons/year while the proposed refineries have the potential of adding additional 2.01 × 1014 tons/year. These concentrations were considered as environmental menace that could have adverse health challenge of the residents of the host communities. Some technologically driven measures to control and subsequently reduce TEX emission from these refineries were suggested.

As part of research efforts to investigate the contribution of various anthropogenic activities to local atmospheric pollution load across Nigeria, the study investigated emission of air pollutants from the combustion processes in Lagos mega city. Solid wastes, consumption of fuel wood, and petroleum products were identified as major materials being combusted in Lagos and these materials were quantified based on the information in literature. Annual emissions from the combustion of the quantified materials were estimated using emission factor approach. The total estimated annual contribution of anthropogenic combustion processes to atmospheric loading of PM10, CO, SO2, NOx and VOC were 188.49, 5920.97, 11.24, 348.88 and 4.14 kt/annum, respectively. Emissions from the combustion of solid waste/biomass were identified as a major source of criteria air pollutants in the city because, about 67.5% and 82% of the estimated CO and PM10 emissions, respectively, were generated from the combustion of solid waste/biomass. Also, 81%, 57% and 32% of NOx, SO2 and CO emissions respectively were found to have emanated from combustion of kerosene. These elevated emission levels can be said to have potential impacts on ambient air quality of the study area. The study concluded that immediate mitigating action to reduce release of pollutants from combustion processes should be put in place.

The indoor air quality (IAQ) is paramount to the existence of humans considering the amount of time spent indoors. The indoor pollutant levels may be 100 times the levels outdoors. The indoor pollutants need to be considered to enhance better IAQ. This study determined the emission factors of carbon monoxide (CO) emitted from a standby electricity generator (SEG). It evaluated the impacts of CO concentrations on indoor air quality and identified appropriate ways to mitigate the CO concentrations. The indoor CO concentration was determined by simulating a number of scenarios of SEG operated outdoor using a Simulation Tool Kit for Indoor Air Quality and Inhalation Exposure (IAQX) model. Hourly measurements of mean CO concentrations in the ambient environment and wind speed were conducted for four weeks in four field locations. The emission rate of CO from the standby electricity generator was measured. The CO concentration from SEG was 2.4289 × 104 mg/m3, a very high CO concentration. The CO emission factors were obtained as 2.2366 × 103 kg/m3 of fuel consumed and 9.5411 × 106 kg/hr of activity. High CO concentrations were obtained in microenvironments from the scenarios 1.28 × 104 mg/m3, 4.78 × 103 mg/m3, 4.79 × 104 mg/m3 and 9.58 × 104 mg/m3. The results showed that a high air exchange rate allowed CO concentrations to decay fast while low air exchange rates created an accumulation of CO concentrations indoor.

The acceptance of liquefied petroleum gas (LPG) cookstove has increased across the country in recent years; however, their performance has not been investigated and established. To achieve this, laboratory tests were carried out to evaluate the thermal efficiency, and industrial combustion analyser (E-instrument E8500) was then used to characterize and quantify the air emissions from combustion of conventional LPG cookstoves in the country. The average thermal efficiency for all tested burners was 66.267 ± 7.218% meeting Tier 4 of the International Organization for Standardization, International Workshop Agreement 11. The mean concentration of CO, NOx, HC, and SO2 was in the range of 3–530, 48–810.5, 99–4176, and 0–4,respectively,and the range of CO2 was 1,792–3,592 mg/m3,which were compared with stationary source limit by Federal Ministry of Environment Standard, Nigeria. The toxicity potential of NOx and SO2 was below unity, 25% of the burners tested were below unity for CO, and HC was higher than unity for all tested burners. Most cookstoves met the guidelines for CO, NOx, and SO2. Hence, LPG in Nigeria could serve as a source of energy for cooking.

The presence of carbon in an environment indicates the need for urgent attention on air quality control. Lagos mega city is presently experiencing developmental projects associated with carbon emission potentials, which are yet to be quantified; hence, this study identified and quantified the sources of carbon emission in the Lagos mega city and also determined the quantity of energy consumption capacity for domestic, transportation and industries. Using fuel consumption rate and activity duration, the emissions factors approach were used to determine the quantity of Carbon dioxide (CO2) emission from the household, vehicular operation and electric power generators in the zones. The total CO2 emission from the three major sectors was then used to establish the carbon footprint and annual global warming potential of the mega city. This study reported a CO2 (g) emission of 9.59 × 1013 tons CO2-e per annum for industrial area and 2.41 × 1016 tons CO2-e per annum for non-industrial area. The overall carbon dioxide emission for Lagos Mega City in 2015 was 2.42 × 1016 tons CO2-e per annum which is higher than the value of 1.6 × 1016 tons CO2-e per annum predicted for Lagos BRT CO2 emission, which stands at 66.1% increase from 2014 to 2015 as the reporting periods.