Monitoring air pollution is of vital importance to the overall health of the population. Unfortunately, devices that can measure air quality can be expensive, and many cities in low and middle-income countries have to rely on a sparse allocation of them. In this paper, we investigate the use of Gaussian Processes for both nowcasting the current air-pollution in places where there are no sensors and forecasting the air-pollution in the future at the sensor locations. In particular, we focus on the city of Kampala in Uganda, using data from AirQo's network of sensors. We demonstrate the advantage of removing outliers, compare different kernel functions and additional inputs. We also compare two sparse approximations to allow for the large amounts of temporal data in the dataset.

We consider the example of a deployment of an air pollution monitoring network in Kampala, an East African city. Air pollution contributes to over three million deaths globally each year(Lelieveld and others, 2015). Kampala has one of the highest concentrations of fine particulate matter (PM 2.5) of any African city Mead (2017) Hence we know little about its distribution or extent. Lower cost devices do exist, but these do not, on their own, provide the accuracy required for decision makers. In our case study, the Kampala network of sensors consists largely of low cost optical particle counters (OPCs) that give estimates of the PM2.5 particulate concentration.

Data collection in economically constrained countries often necessitates using approximate and biased measurements due to the low-cost of the sensors used. This leads to potentially invalid predictions and poor policies or decision making. This is especially an issue if methods from resource-rich regions are applied without handling these additional constraints. In this paper we show, through the use of an air pollution network example, how using probabilistic machine learning can mitigate some of the technical constraints. Specifically we experiment with modelling the calibration for individual sensors as either distributions or Gaussian processes over time, and discuss the wider issues around the decision process.

AI training data provider Samasource has raised a $14.8 million Series A funding round led by Ridge Ventures. The San Francisco headquartered company delivers Fortune 100 companies with the inputs they need for machine learning development in fields including autonomous transportation, e-commerce and robotics. And it does so with a global work-force of data-specialists, a large number of whom are located in East Africa. In addition to San Francisco, New York and the Hague, Samasource has offices and teams in Kenya and Uganda. The company has a global staff of 2900 and is the largest AI and data annotation employer in East Africa, according to CEO and founder Leila Janah.