Air pollution/sources of air pollution and health effects
Air pollution/sources of air pollution
Air pollution represents environmental risk to health. By decreasing levels of air pollution, countries can reduce the burden of disease caused by stroke, heart disease, lung cancer, and respiratory, chronic or acute diseases, including asthma.
The short and long term cardiovascular and respiratory health of the population is inversely proportional to the level of air pollution.
The WHO Air Quality Guidelines evaluate the effects of air pollution on health and provide threshold values beyond which it is harmful.
In 2016, 91% of the world’s population lived in areas where WHO’s air quality guidelines were not respected.
In 2016, there were an estimated 4.2 million premature deaths worldwide caused by ambient (outdoor) air pollution in urban, peri-urban and rural areas.
Some 91% of these premature deaths occurred in low- and middle-income countries, with the largest number recorded in the WHO Regions of South-East Asia and the Western Pacific.
Some of the major sources of urban air pollution could be reduced by policies and investments for greener transport, but also for housing, electricity generation and energy-efficient industries. optimized waste management in municipalities.
In addition to outdoor air pollution, domestic smoke poses a serious health risk to about 3 billion people who cook, heat and light their homes with biomass, fuel and coal fuels. .
Indoor and outdoor air pollution is a major environmental health problem affecting low, middle and high income countries alike.
In 2016, there were an estimated 4.2 million premature deaths worldwide caused by ambient (outdoor) air pollution in urban and rural areas; this mortality is due to exposure to particles with a diameter of 2.5 microns or less (PM2.5), which cause cardiovascular and respiratory diseases, and cancers.
People living in low- and middle-income countries pay a disproportionate toll on outdoor air pollution: 91% (of the 4.2 million premature deaths that are due to it) occur in these countries, the Regions of the Southeast Asia and the Western Pacific bear the heaviest burden.
The latest estimates of the burden of disease show the important role played by air pollution in cardiovascular diseases and deaths. There is growing evidence of links between ambient air pollution and cardiovascular risk, including studies in highly polluted areas.
WHO estimates that approximately 58% of premature deaths from outdoor air pollution resulted in 2016 from ischemic heart disease and stroke, 18% from chronic obstructive pulmonary disease or acute lower respiratory tract infections, while the remaining 6% is attributable to lung cancer.
The findings of an evaluation carried out in 2013 by the International Agency for Research on Cancer (IARC) of WHO showed that outdoor air pollution was carcinogenic, with particulate matter being the most closely associated pollutant increased incidence of cancers, especially lung. A link has also been established between air pollution and the increase in the number of cancers of the urinary tract / bladder.
To protect public health, it is essential to combat all the risk factors for noncommunicable diseases, including air pollution.
Most sources of outdoor air pollution are totally beyond the control of individuals and require concerted action at local, national and regional level by officials from the transport, energy, waste management, water and waste management sectors. town planning and agriculture.
There are many examples of policies that have succeeded in reducing air pollution in the areas of transport, urban planning, power generation and industry:
industry: promote clean technologies that limit smokestack emissions; and improved management of urban and agricultural waste, including the opening of methane capture sites from waste (for use as biogas) as an alternative to incineration;
energy: ensuring access to clean and affordable solutions for cooking, heating and lighting;
Fine particulate matter (PM2.5)
10 μg / m3 annual average
25 μg / m3 average over 24 hours
Coarse Particulate Matter (PM10)
20 μg / m3 annual average
50 μg / m3 average over 24 hours
In addition to the recommended values, the guidelines establish intermediate targets for PM10 and PM2.5, with a view to promoting a gradual transition to reduced concentrations.
If they were affected, it is likely that these targets would result in significant reductions in the risk of acute and chronic conditions due to air pollution. The values advocated in the guidelines, however, are the objective to be achieved.
Suspended particulates produce effects on health that can be observed at levels of exposure to which a large number of people are subjected in urban and rural areas of developed and developing countries; however, exposure levels are often significantly higher in fast-growing cities than in previously developed cities of comparable size.
According to the WHO Air Quality Guidelines, lowering the annual PM2.5 PM2.5 particulate matter concentration of 35 μg / m3, a level commonly recorded in many developing cities, at 10 μg / m3, is level advocated by WHO, could reduce the mortality rate of air pollution by about 15%. Nevertheless, even in the European Union, where a large number of cities observe the limits recommended by the Organization, it is estimated that the average life expectancy is reduced by 8.6 months because of the exposure of the population to fine particles from human activity.
In low- and middle-income countries, exposure to indoor pollutants released from domestic use of polluting fuels in open fires or traditional stoves increases the risk of acute respiratory infection. cardiovascular disease, chronic obstructive pulmonary disease and lung cancer in adults.
Important health risks are associated with exposure to fine particles, but also to ozone (O3), nitrogen dioxide (NO2) and sulfur dioxide (SO2). As is the case for particulates, concentrations of these molecules are generally higher in urban areas of low- and middle-income countries. Ozone is one of the leading risk factors for asthma-related morbidity and mortality, with nitrogen dioxide and sulfur dioxide affecting asthma, bronchial disease, pulmonary inflammation and impairment of lung function.
100 μg / m3 average over 8 hours
On the basis of recent links between daily mortality and airborne ozone, the ozone threshold recommended in the WHO Air Quality Guidelines has been lowered compared to previous editions which amounted to 120 μg / m3.
Definition and main sources
Ozone from the protective layer in the upper atmosphere should not be confused with that found at ground level, which is one of the main constituents of photochemical smog. In this case, the ozone is formed under the effect of photochemical reactions (that is to say in the presence of solar radiation) between various pollutants, such as nitrogen oxides (NOx) emitted by the vehicles and the industry and volatile organic compounds (VOCs), emitted by vehicles, solvents and industry. Peaks of concentration are observed during periods of sunny weather.
At too high concentrations, ozone has marked effects on human health. Respiratory problems, the onset of asthma attacks, a decrease in lung function and the appearance of respiratory diseases are observed.
Nitrogen dioxide (NO2)
40 μg / m3 annual average
200 μg / m3 hourly average
The current WHO guideline value of 40 μg / m3 (annual average) has been set to protect the public from the health effects of NO2 gas.
Definition and main sources
In the air, NO2 has the following effects:
At concentrations exceeding 200 μg / m3 over short periods of time, it is a toxic gas that causes significant inflammation of the respiratory tract.
It is the main agent responsible for the formation of nitrate aerosols, which represent a significant proportion of PM2.5 and ozone, in the presence of ultraviolet rays.
Anthropogenic emissions of NO2 come mainly from combustion (heating, electricity generation, engines of motor vehicles and boats).
Epidemiological studies have shown that bronchitic symptoms in children with asthma