The measurements will help determine the composition of particles from car exhausts and other sources of fuel combustion as well as factory emissions, soil dust and sea-salt spray. This will be valuable information for determining the sources of Jakarta's fine particles. The samplers rely on impregnated filter paper absorbing these gases. Early results High concentrations of fine particles in central Jakarta are primarily due to motor vehicle emissions. Occasional high lead levels confirm motor vehicles as a significant pollution source.
Leaded petrol is still common in Indonesia.
The levels appear to often exceed World Health Organization maximum guidelines. But even higher lead levels in Bogor point to other, local, sources. 5 levels are usually higher in central Jakarta than at the other sites. Nephelometer readings show that local visual distances in Jakarta are poor, typically between 5 and 17 kilometres. The morning peak coincides with peak traffic volume, whereas the evening peak may be the result of a more complex combination of traffic and domestic emissions, chemical reactions in the air and changes in atmospheric stability.