Temperature and heat in informal settlements in Nairobi

Area of Science:

• Urban Climatology
• Environmental Health
• Geographic Information Systems

Background:

• Nairobi, Kenya, presents diverse micro-climates and surface heterogeneity, with distinct temperature variations between the central business district and informal settlements.
• Informal settlements are characterized by dense housing, limited green spaces, and inadequate public services, potentially exacerbating heat exposure.

Purpose of the Study:

• To investigate the spatial variations in temperature and humidity across Nairobi's diverse urban landscape.
• To quantify the differences in thermal conditions between informal settlements and other urban areas.
• To explore the relationship between surface properties and observed temperature variations.

Main Methods:

• Deployment of a high-density observation network in 2015/2016 to collect summertime temperature and humidity data.
• Analysis of temperature, humidity, and heat index variations in informal settlements, including Kibera.
• Correlation of thermal data with satellite-derived surface properties like albedo and vegetation indices, as well as elevation data.

Main Results:

• Informal settlements, such as Kibera, exhibited consistently higher temperatures and heat index values compared to the Dagoretti observation station.
• Observed temperature increases were several degrees Celsius higher in informal settlements.
• These elevated temperatures align with ranges previously linked to increased mortality in vulnerable populations.

Conclusions:

• Urban planning and infrastructure development in Nairobi must consider micro-climate variations, especially in informal settlements.
• The study highlights the significant impact of surface properties on urban heat island intensity within informal settlements.
• Findings underscore the urgent need for interventions to mitigate heat-related health risks in Nairobi's vulnerable communities.