United Nations Environment Programme

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Tool 3: Health effects

Pollutant emissions cause poor air quality and affect your health

Health impacts from air pollution vary in nature and severity, and can include everything from hospitalization and asthma attacks to premature deaths (See below).

From a global perspective, the World Health Organisation estimated in 2002 that over 800,000 people die prematurely due to air pollution. However, many more people suffer from other impacts, such as air pollution-related cancers, reduced child development, asthma attacks, and bronchitis. The pyramid in Figure 1 illustrates the relative number of people who suffer from the various health impacts. Tool 4 provides health impact estimates from a number of selected cities.

While some pollutants cause acute health effects, others cause chronic effects after long periods of exposure. The most common health impacts related to air quality are respiratory diseases and cardiovascular (heart and circulatory system) diseases. 

Figure 2. Health pyramid. Source: Mike Walsh

Acute impacts: Carbon monoxide (CO) is a well-known pollutant that can cause acute impacts. CO reduces the capacity of the blood to carry oxygen to the body’s tissues and organs, impairing organ function, which – with very high CO concentrations – can result in death. CO concentrations can increase to dangerous levels in conditions such as rooms with badly maintained gas heaters or in garages with inadequate ventilation systems. Ground-level ozone (or photochemical smog) can also have acute health impacts, especially for the elderly or people with poor lungs.

  • In 1952, London suffered from extremely high levels of ground-level ozone that was estimated to have caused 4,000 premature deaths within a five-day period.

Long-term impacts:The health impacts resulting from inhaling air with high concentrations of particles and ground-level ozone that affect most people are long-term. PM10 concentrations are commonly used as a proxy for all air pollutants when estimating long-term health impacts, as particulate matter has the most serious health consequences and many other pollutants also can be included in the measurement of PM concentrations (e.g. sulphates, HC and NOx). PM concentrations affect human health by causing breathing problems and asthma which, in the worst cases, can lead to premature death. The extent of illness depends upon the size and chemical composition of the particulate matter. Particles emitted by diesel motor vehicles are the most problematic because they contain a large percentage of fine particles (PM2.5).

  • In Europe alone, fine particles (PM2.5) are estimated to cause more then 386,000 deaths per year.

The animation below provides an explanation of the long-term impacts of particulate matter.

Health Effects

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