Pollution, Asthma, and Poverty

Air pollution – the combination of particulate matter and ozone – is a major environmental health problem and a leading risk factor for death globally. Nitrogen dioxide (NO2) constitutes a major component of particulate matter. As such, air pollution is often measured by mean concentration of NO2 particles per cubic meter of air volume (μg/m3).1

This air pollutant can cause stroke, heart disease, lung cancer, and respiratory diseases. For instance, it can lead to significant inflammation of the airways, which adversely affects the respiratory system and exacerbates asthma. Therefore, the health burden of air pollution can be measured by the number of asthma-related hospitalisations in an area.2

In 2017, air pollution caused 4.9 million deaths globally, making it the fourth highest risk factor of death, after high blood pressure, smoking, and high blood sugar. In other words, nearly 1-in-10 of all deaths around the world were directly related to air pollution.3

Combustion processes, from heating, power generation, and engines in vehicles and ships, are the primary source of air pollution. As such, health risks due to air pollution are particularly prevalent in low- and middle-income countries, because of industrialisation and the use of solid fuels for cooking. Geographical factors, such as dry conditions, sand and dust sources, exacerbate this problem.4

This income-based disparity in air pollution-related health problems is reflected locally within cities, as low-income areas tend to have more air pollution, as well as greater health risks associated with air pollution. One reason is that low-income neighbourhoods are often located near polluting disamenities like major roads and power plants.5, 6

The following maps visualise the data on air pollution, measured by NO2 μg/m3, and its associated health risks, measured by the number of asthma-related hospitalisations, in London and New York City, by borough/neighbourhood. It is critical to note that these maps are not intended to show causation; rather, they simply show the spatial distribution of the problem, from which correlation can be inferred.

London NO2 Concentration

London Asthma and Income

New York City NO2 Concentration

  1. Hannah Ritchie and Max Roser (2020) - "Air Pollution". Published online at Retrieved from: '' [Online Resource]
  2. World Health Organisation (2018) – “Ambient (Outdoor) Air Pollution.” Retrieved from: ‘’ [Online Resource]
  3. GBD 2017 Risk Factor Collaborators. "Global, regional, and national comparative risk assessment of 84 behavioural, environmental and occupational, and metabolic risks or clusters of risks for 195 countries and territories, 1990–2017: a systematic analysis for the Global Burden of Disease Study 2017." Lancet (London, England) 392.10159 (2018): 1923.
  4. Hajat, Anjum, Charlene Hsia, and Marie S. O’Neill. "Socioeconomic disparities and air pollution exposure: a global review." Current environmental health reports 2.4 (2015): 440-450.
  5. Bell, Michelle L., and Keita Ebisu. "Environmental inequality in exposures to airborne particulate matter components in the United States." Environmental health perspectives 120.12 (2012): 1699-1704.
  6. Union of Concerned Scientists (2019) – “Inequitable Exposure to Air Pollution from Vehicles in California.” Retrieved from: ‘’ [Online Resource]