Air pollution status and sources of black carbon aerosols in Nairobi, Kenya

August Andersson, Leonard Kirago, Örjan Gustafsson, Michael Gatari

The dataset includes year-round concentration of PM2.5 fine particles and its constituents, together with radio-carbon (Δ¹⁴C) signatures of black carbon aerosols (BC) for aerosol samples collected in Nairobi between February 2014 and February 2015.

The carbon isotope data is used to quantify the relative contribution of the two main emissions sources of black carbon in Nairobi, namely fossil fuel combustion and biomass burning.

The sampling site was located on a rooftop of one of the University of Nairobi buildings.

Citation

August Andersson, Leonard Kirago, Örjan Gustafsson, Michael Gatari (2022) Air pollution status and sources of black carbon aerosols in Nairobi, Kenya. Dataset version 1. Bolin Centre Database. https://doi.org/10.17043/andersson-2022-nairobi-1

References

Kirago L, Gatari MJ, Gustafsson Ö, Andersson A (2022) Black carbon emissions from traffic contribute substantially to air pollution in Nairobi, Kenya. Communications Earth & Environment. https://doi.org/10.1038/s43247-022-00400-1

Data description

The data is provided in one xlsx spreadsheet file that contains concentration data (PM2.5, carbonaceous aerosols, water-soluble inorganic ions) 4-days cumulative rainfall, ¹⁴C-BC, and source apportionments of elemental carbon (EC) (fraction fossil and fraction biomass burning). The same data are also provided in one comma-separated (csv) file.

Data file content

• Sample code
• Week day
• Start date
• Stop date
• Fine particles
  • PM2.5 (μg/m³)
• Carbonaceus aerosols
  • OC (μgC/m³)
  • BC (μgC/m³)
• Cations
  • Na⁺ (ng/m³)
  • NH⁴⁺ (ng/m³)
  • K⁺ (ng/m³)
  • Mg²⁺ (ng/m³)
  • Ca²⁺ (ng/m³)
• Anions
  • F⁻ (ng/m³)
  • Cl⁻ (ng/m³)
  • NO³⁻ (ng/m³)
  • PO₄³⁻ (ng/m³)
  • SO₄²⁻ (ng/m³)
• EC ¹⁴C
  • ¹⁴C pMC BC (%)
• 4-days cumulative rains
  • Rainfall (mm)
  • D14C (‰)
  • ƒfossil
• Source apportionment
  • ƒbiomass
  • BC biomass(μg/m³)
  • BC fossil (μg/m³)

Comments

The sampling site is located on a rooftop of one of the University of Nairobi buildings, Nairobi, Kenya.

Location: 1.279° S, 36.817° E. Height above ground level: 17 m. Height above sea level: 1690 m asl. Sampling duration: February 2014⁠ – ⁠February 2015. Sampling type: PM2.5 inlet; quartz fibre filter samples.

Carboneceous aerosol concentrations were obtained by thermal optical transmission analysis (TOT; Sunset Laboratory, Tigard, Oregon) using NIOSH 5040 protocol, for each of the PM2.5 samples, collected in Nairobi between March 2014 and February 2015. Anion and cations were analysed using Dionex Aquion ion chromatography instrument (Thermo Finnigan LLC).

Every second sample (excluding blanks), was selected for isolation and cryo-trapping of BC (n = 28), using a modified Sunset TOT instrument. The samples were analysed for ¹⁴C using accelerator mass spectroscopy at Tandem laboratory at Uppsala University, Sweden.