The proportion of the urban population living in slums worldwide declined by 20 per cent between 2000 and 2014 (from 28 per cent to 23 per cent). That positive trend recently reversed course, and the proportion grew to 23.5 per cent in 2018. The absolute number of people living in slums or informal settlements grew to over 1 billion, with 80 per cent attributed to three regions: Eastern and South- Eastern Asia (370 million), sub-Saharan Africa (238 million) and Central and Southern Asia (227 million). An estimated 3 billion people will require adequate and affordable housing by 2030.

The growing number of slum dwellers is the result of both urbanization and population growth that are outpacing the construction of new affordable homes. Adequate housing is a human right, and the absence of it negatively affects urban equity and inclusion, health and safety, and livelihood opportunities. Renewed policy attention and increased investments are needed to ensure affordable and adequate housing for all by 2030.

Public transport is an essential service for urban residents and a catalyst for economic growth and social inclusion. Moreover, with ever-increasing numbers of people moving to urban areas, the use of public transport is helping to mitigate air pollution and climate change. According to 2018 data from 227 cities, in 78 countries, 53 per cent of urban residents had convenient access to public transport (defined as residing within 500 metres walking distance of a bus stop or a low-capacity transport system or within 1,000 metres of a railway and/ or ferry terminal). In most regions, the number of people using public transport rose by nearly 20 per cent between 2001 and 2014. Sub-Saharan Africa lagged behind, with only 18 per cent of its residents having convenient access to public transport. In some regions with low access, informal transport modes are widely available and, in many cases, provide reliable transport. Stronger efforts are needed to ensure that sustainable transport is available to all, particularly to vulnerable populations such as women, children, seniors and persons with disabilities.

Globally, 2 billion people were without waste collection services, and 3 billion people lacked access to controlled waste disposal facilities, according to data collected between 2010 and 2018. The problem will only worsen as urbanization increases, income levels rise and economies become more consumer-oriented. The total amount of waste generated globally is expected to double from nearly 2 billion metric tons in 2016 to about 4 billion metric tons by 2050.

The proportion of municipal solid waste collected regularly increased from 76 per cent between 2001 and 2010 to 81 per cent between 2010 and 2018. But that does not mean that it was disposed of properly. Many municipal solid waste disposal facilities in low- and middle-income countries are open dumpsites, which contribute to air, water and soil pollution, including by plastic waste, as well as emissions of greenhouse gases such as methane. Investment in waste management infrastructure is urgently needed to improve the handling of solid waste across much of the world.

Nine out of ten urban residents in 2016 were breathing polluted air—that is, air that did not meet the WHO air quality guidelines for annual mean levels of fine particulate matter (PM2.5) of 10 micrograms or less per cubic metre. More than half of those people were exposed to air pollution levels at least 2.5 times above the guideline value. Air quality worsened between 2010 and 2016 for more than 50 per cent of the world’s population. Central and Southern Asia and sub-Saharan Africa are the two regions that saw the largest increases in particulate matter concentrations.

In low- and middle-income countries, the air quality of 97 per cent of cities with more than 100,000 inhabitants did not meet air quality guidelines in 2016, compared to 49 per cent in high-income countries. Ambient air pollution from traffic, industry, power generation, waste burning and residential fuel combustion, combined with household air pollution, poses a major threat to both human health and efforts to curb climate change. More than 90 per cent of air-pollution-related deaths occur in low- and middle-income countries, mainly in Asia and Africa.

A connective matrix of streets and public spaces forms the skeleton of the city upon which everything else rests. Where public space is inadequate, poorly designed or privatized, the city becomes increasingly segregated. Investment in networks of streets and open public spaces improves urban productivity, livelihoods and access to markets, jobs and public services, especially in countries where over half of the urban workforce is informal.

Based on 2018 data from 220 cities, in 77 countries, few cities have been able to implement a system of open public spaces that covers entire urban areas—that is, within easy reach of all residents. Findings show that the average share of the population within 400 metres walking distance of an open public space is around 31 per cent, with huge variations among cities (from a low of 5 per cent to a high of 90 per cent). A low percentage does not necessarily mean that an inadequate share of land is open public space, but rather that the distribution of such spaces across the city is uneven.