AIR POLLUTION: CAUSES, TYPES, SOLUTIONS, CONSEQUENCES - ENVIRONMENT - 2025

The pollution of the air occurs when the composition is altered, either incorporating new elements or by increasing the proportions of existing. By definition, any element present in the air that affects human health is a pollutant.

Most of the living beings that exist today are adapted to the current composition of the air and depend on it to live. Humans are particularly susceptible to changes in the composition of the air they breathe.

Air pollution in eastern China. Source: See page for author

The main components of air are oxygen (21%) and nitrogen (78%), in addition to argon, carbon dioxide and water vapor. By emitting additional CO2, the proportion of this in the air increases, which is toxic to humans.

Likewise, if solid particles suspended in the air are added, they penetrate the respiratory tract, affecting health. In addition, the air can be polluted by biological pathogens and many viral, bacterial and fungal diseases are transmitted by it.

With pollution, the quality of the air decreases and the respiration of living beings is affected, which can suffer different respiratory conditions from mild to even fatal. They can also cause or aggravate heart problems and even strokes.

Causes of air pollution

Air pollution can occur by natural causes or by human action (anthropic causes). Natural causes include gas and particle emissions from volcanic eruptions, swamp gases, and accumulations of gases in mines or caves.

Also, forest fires of natural origin give off polluting particles. Air pollution from viruses, bacteria, fungal spores, and pollen grains can be natural or affected by human activities.

Regarding anthropic causes, gas emissions from motor vehicle traffic and industrial activity stand out. Likewise the burning of fossil fuels for heating and fires of man-made origin (forest and waste).

Although there are natural and anthropic causes, we will focus on those of anthropic origin. This is because they are causing a recurring impact on air quality.

- Industrial processes

The various industrial processes emit different gases and particles into the atmosphere.

Emission of gases

For example, the paper industry emits dioxins as a result of chlorine-based paper bleaching processes. The petrochemical industry contributes CO2, nitrogen oxides and sulfur oxides among other compounds.

Air pollution from industrial emissions. Source: National Park Service

The companies that contribute the most to CO2, SO2 and mercury emissions are energy companies, due to the use of coal.

Paints and lacquers

Painting and lacquering of surfaces, both in construction, the automotive industry and other areas generates suspended particles. These particles of paints, varnishes and lacquers are in most cases toxic.

The textile industry

This is considered the second most polluting industry after the oil one. Textile manufacturing emits oil and acid mists, dust, fibers, solvent vapors and odors.

These contaminants are mainly produced during the garment finishing process.

- Automotive traffic

Large concentrations of vehicles in cities contribute various pollutants to the air, both gases and material particles. Automotive traffic is one of the biggest sources of CO2, but they also scatter carbon particles.

Diesel

Vehicles that use diesel fuel pollute an average of four times more than those that use gasoline. This type of vehicle emits hundreds of gaseous and solid substances into the air.

Air pollution from motor vehicles. Source: Ruben de Rijcke

These include CO2, carbon monoxide, sulfur dioxide, and nitrogen oxides. Likewise, they emit volatile organic compounds such as benzene and elemental carbon particles, sulfur sulfates, heavy metals and various organic particles are released.

- Burning of fossil fuels

Petroleum

The refining of oil to produce gasoline, diesel, lubricants, plastics and other derivatives releases a large amount of polluting gases and particles. Among the gases released are monoxide, carbon dioxide, nitrogen oxides, and sulfur dioxide.

Also, various types of material particles are generated, especially heavy metals.

Coal

In many countries, coal is the most used fuel for heating and this meant that 46.5 tons of CO2 equivalent were emitted by 2017. On the other hand, the burning of coal is the main source of SO2 and mercury released into the air.

- Domestic combustion

It is estimated that combustion in homes is responsible for 12% of global pollution by environmental fine particles (PM2.5). Wood or charcoal stoves generate smoke that, according to the World Health Organization, is responsible for 33% of respiratory diseases.

- Forest fires

Wildfires release millions of tons of greenhouse gases and acid rain into the atmosphere annually. On the other hand, they incorporate material particles of different diameters into the environment that pollute the air, affecting health.

- Agriculture and Livestock

Use of biocides

During the application of biocides, especially through the aerial spray system, large quantities of the product are carried away by air currents. Depending on the product in question, the effects can range from skin irritations to serious respiratory problems.

Sugarcane

The management of this crop involves controlled burning prior to harvest. This agricultural practice transforms the crop into a source of CO2 and fine particles to the atmosphere.

- Landfills

Garbage dumps, especially open dumps, are a source of air pollution. This occurs both by burning them and by the decomposition of waste.

Burning also affects another parameter of air pollution called “offensive odors”. The bad odors generated by garbage also affect the quality of life of the adjacent towns.

- Sick building syndrome

Many old or poorly maintained buildings generate various pollutants that affect the health of those who live or work there. These pollutants include lime, paint and cement particles from the walls and the presence of molds in air conditioning systems.

- Cigarette smoke

The smoke emitted by the burning of tobacco in cigarettes and cigars releases numerous substances into the environment, many of them indicated as carcinogenic. Passive exposure to these pollutants can cause pneumonia in children and 9.3% of cases of respiratory infections are related to this cause.

Consequences

Of the top 10 causes of environment-related deaths, chronic respiratory diseases rank fifth. For their part, respiratory infections are the seventh leading cause of death.

According to the UN, air pollution is a silent killer that affects 90% of the world's population. It is estimated that it causes the death of around 7 million people a year, where the most vulnerable are the elderly and children.

- Diseases

In 2016, more than 90% of the world's population lived in places where the air is not safe to breathe, according to the World Health Organization (WHO).

Inert agent diseases

Among the diseases generated are chronic obstructions, lung cancer, ischemic heart disease and strokes.

Allergies

The so-called aeroallergens are material particles suspended in the air that produce allergic reactions of the immune system. These allergens include dust, pollen grains, dust mites, and pet hair.

High concentrations of pollen grains in the air cause allergic reactions in susceptible people (pollinosis). Symptoms include conjunctivitis, rhinitis, nasal obstruction, sneezing, and hydrorrhea (nasal fluid).

In some places the so-called hay fever or spring fever related to this phenomenon are recurrent.

Pathogenic diseases

Various diseases caused by viruses, bacteria and fungi are transmitted through the air, especially in closed and poorly ventilated environments. One case is nosocomial pneumonia, caused by the Streptococcus pneumoniae bacteria that occurs in hospitals, being an important cause of mortality.

Legionellosis, caused by the bacterium Legionella pneumophila, is spread through water vapor in air conditioners. Depending on how it is expressed, this disease can range from a mild cough to severe, even fatal pneumonia.

Common flus are viral illnesses that are also transmitted through the air. On the other hand, Coccidioides immitis is a pathogenic fungus whose spores from the soil are spread on the dust and carried by the wind.

Likewise, the fungus Aspergillus fumigatus causes diseases in immunosuppressed patients and aspergillosis in bees.

- Work environment and decreased productivity

A work environment without air quality causes problems in workers, with the consequent loss of productivity. In areas such as textile manufacturing, carpentry, metallurgy and others, the risks related to particles in the air are high.

- Quality of life, social productivity and economic losses

All the foregoing leads to a decrease in the quality of life of the population. On the other hand, related respiratory diseases cause absenteeism from school and work, as well as large direct and indirect economic losses.

Types

There are three basic forms of air pollution which are chemical, physical and biological. In the first case, due to the emission of polluting gases or toxic substances (biocides and other chemical products). One of the main polluting gases is CO2, as well as O3 (tropospheric ozone), NOx, SO2 and others.

In physical terms, it is the incorporation into the air of material particles, either by combustion of materials or industrial processes. For example, the burning of fuel by motor vehicles or coal in thermoelectric plants disperses particles in the air.

On the other hand, in certain work environments the accumulation of suspended particles pollutes the air. For example the textile, metallurgical and wood industries are potentially risky in this regard.

As for biological contamination, viral diseases such as the common flu or bacterial diseases such as tuberculosis are transmitted through the air. In the same way, the air can carry spores of pathogenic fungi that cause serious lung diseases.

- Chemical contamination

Carbon monoxide and dioxide (CO and CO2)

Carbon monoxide (CO) has its main source in the incomplete combustion of vehicle engines. It is a very dangerous gas since when inhaled in high concentrations it replaces oxygen in the blood and can cause death.

The World Meteorological Organization pointed out that the global average concentration of CO2 went from 403.3 ppm in 2016 to 405.5 ppm in 2017. This last level represents 146% more than what existed in the pre-industrial era (before 1750).

Nitrogen oxides (NOx)

These gases are corrosive and act as catalysts forming mists when reacting with hydrocarbons in the presence of solar radiation. When they come into contact with moisture in the atmosphere, they form nitric acid which precipitates with the rain, forming acid rain.

In 2017 its atmospheric concentration was 329.9 ppm, which is 122% of its level in the pre-industrial era.

Sulfur dioxide (SO2)

It is a dense gas that is heavier than air and comes from burning fossil fuels. It comes mainly from motor vehicles, oil refineries and thermoelectric plants (coal).

This gas generates constituent particles of PM10 (particles of 10 µm or less) and PM2.5 (of 2.5 µm or less). When people are exposed to prolonged contact with this gas, it causes eye irritation, respiratory problems and bronchitis.

Ground-level ozone (O3) or ground level ozone

Tropospheric ozone is formed at ground level, unlike ozone that forms the so-called ozone layer. It originates as a result of photochemical reactions that occur in the presence of polluting gases (NOx and volatile organic hydrocarbons) and oxygen.

These gases come mainly from automotive traffic, but also from industrial activity. Ozone is a very oxidizing gas, so it has damaging effects on living tissues, causing serious illnesses.

Volatile Organic Compounds (VOCs)

Volatile Organic Compounds are chemical substances that contain carbon and that when reacting with nitrogen oxides, form O3. Some examples of VOCs are benzene, formaldehyde and solvents, such as toluene and xylene among others.

One of the most common is benzene, the main sources of which are tobacco smoke, automotive exhaust, and industrial emissions.

These compounds if they penetrate the circulatory system can seriously affect various organs and even promote cancer. Such is the case of benzene, which can cause damage to the bone marrow and lead to anemia.

In fact, the US Environmental Protection Agency lists VOCs as carcinogenic to humans.

Dioxins and furans

In combustion processes involving chlorine-based compounds, dioxins and furans are generated. They can be formed both in industrial processes, such as the manufacture of plastics or paper and in the burning of waste, particularly plastics.

Some natural phenomena, such as forest fires and volcanic eruptions, can also generate these compounds. Dioxins and furans are highly toxic and have been identified as carcinogens.

- Physical contamination

One of the most serious health risks associated with air pollution is the presence of particulate matter in suspension. The most dangerous are those smaller than 10 μm (0.01 mm) in diameter.

These particles can penetrate deep into the lung alveoli and often consist of hydrocarbons and toxic metals.

Particulate matter (PM)

These material particles are emitted into the environment both by combustion processes, as aerosol applications and various erosive industrial processes. Combustion engines (especially diesel) and solid fuel burning (especially coal) are two of the most important sources of particulate matter.

Air pollution from forest fires. Source: Nerval

Another source of these particles is smoke from burning fuels in the home for heating or cooking, incineration of solid waste and mining. In foundries and the textile industry, waste is generated in the form of suspended particles, affecting the working environment.

On the other hand, natural phenomena such as volcanic eruptions and sand storms saturate the air with physical pollutants.

Classification

For the evaluation of air quality, international organizations such as the World Health Organization define categories of particles. The classification is given according to the size in a range between 0.1 and 10 μm (0.0001 and 0.1 mm).

PM10 particles are those whose diameter is equal to or less than 10 μm (0.01 mm) in diameter. The so-called "fine particles" are PM2.5, that is, those with a diameter of 2.5 µm or smaller.

On the other hand, "ultrafine particles" or PM0.1 are those with diameters of 0.1 µm or less. The smaller the particles, the greater the ability to penetrate deep into the body and even enter the bloodstream.

The category of PST (Total Suspended Particles) is also considered, including the set of material particles regardless of their dimensions.

Heavy metals

Depending on the source, the particulate matter in suspension can contain different heavy metals, which are highly toxic. Among them titanium (Ti), vanadium (V), chromium (Cr), nickel (Ni) and lead (Pb).

Effects edit

In general, they cause respiratory problems and inflammatory processes, even causing conditions such as intravascular coagulation, anemia and even leukemia.

- Biological contamination

Airborne pathogens

There are various pathogenic organisms whose mode of transmission is by air such as viruses, bacteria and fungi. The most common viruses in this regard are flu viruses, which even have regular cycles depending on the seasons of the year.

Bacteria such as the tuberculosis bacillus are also transmitted through the air and are associated with poor diet. The latter due to the presence of a depressed immune system.

For their part, fungi are dispersed by spores that are easily transported through the air. Upon entering the respiratory system, these spores germinate and cause serious respiratory complications.

Pollen grains

The cycles of certain plant species, especially those of anemophilic pollination (by wind) generate large masses of pollen in suspension. In this, grasses are especially efficient, due to the large amount of pollen they produce and their large populations.

Pollen grains are allergenic for many people, that is, when they come into contact with the mucous membranes they trigger immune processes. This can cause fever, nasal congestion, and other reactions depending on susceptibility.

Solutions

To control air pollution it is necessary to take measures to reduce the emission of polluting gases and particles. This implies legal and technological measures such as the establishment of national and international legal provisions for the reduction of emissions.

A monitoring system is also important to assess air quality and detect important alterations in time. The main air pollutants permanently monitored are particulate matter less than 10 as well as CO2, O3 and pollen in the air.

It is also necessary to reduce dependence on fossil fuels and increase the use of clean energy (hydroelectric, solar, wind, geothermal).

Some Latin American cities have serious air pollution problems, for example Mexico City and Lima (Peru). While in Colombia, cities such as Bogotá and Cúcuta present worrying levels of suspended material particles.

In Venezuela, the main problem of air pollution is suspended material particles, especially PM10.

- Awareness and information

It is essential to raise awareness in the public regarding the causes, consequences and preventive measures against air pollution. This allows taking the appropriate personal precautions, as well as constituting the necessary social pressure to achieve government attention to the problem.

In most cases, people do not associate health problems with the quality of the air they breathe.

Timely information

A conscientious citizen also requires timely information regarding air quality. This warrants having a monitoring and follow-up network that provides constant public information.

- Legislation

It is essential to establish a legal system that contemplates the application of international standards and norms to avoid air pollution. Likewise, everything related to the work environment, where in some cases the risks are greater.

International agreement

Atmospheric processes can disperse pollutants beyond national borders. In this sense, it is essential that the problem of air pollution is addressed as a global issue and not exclusively a national one.

Although international agreements have been established to control certain types of emissions, this is still incipient and ineffective. Such is the case of the Kyoto Agreement on greenhouse gases, which has not met the established goals.

- Monitoring and control

Accompanying the legislation, a monitoring system for compliance is necessary. Similarly, a permanent control for the detection of infractions or accidents and the corresponding mitigation of damages.

Control system

Given the seriousness of the problem, the countries establish air quality surveillance systems. This involves a network of stations that take samples from it and evaluate the relevant parameters.

These include the gases present and their concentration (especially CO2 and O3) as well as particulate matter (including pollen).

In addition, it is necessary to correlate the meteorological variables, since they have a decisive influence on the behavior of pollutants in the air. Among these variables are precipitation, solar radiation, wind speed and direction.

- Technological applications

Waste management

The best way to reduce air pollution is by reducing the generation of waste. In this sense, the three Rs approach (reduce, reuse and recycle) contributes to less waste production.

On the other hand, in those cases where it is necessary to resort to burning waste, appropriate measures must be taken. For this, technology increasingly provides incineration systems with more efficient gas and particle filters.

Industrial process efficiency

Today, process reengineering and technological advancements allow greater efficiency in production processes to reduce contaminants.

Technological improvements for environmental purposes are not always profitable for companies, so tax incentives must be established.

Use of clean energy sources

One of the main sources of air pollution is the gases and material particles emitted by the burning of fossil fuels. Therefore, it is essential to replace these energy sources with clean renewable energies such as hydroelectric, solar, geothermal and wind.

Transport

In large cities one of the most impactful sources of air pollution is motor vehicles. In this sense, the technological level of the vehicle fleet is essential to reduce polluting gas emissions.

An alternative that has been advancing is the replacement of gasoline and diesel vehicles with electric vehicles. In some cities, this initiative is more advanced, such as Madrid and Santiago de Chile or in Germany where there is already an electric highway for trucks.

- Vegetation cover as environmental filters

Plants are natural air filters as they take in CO2 from the environment, fix carbon in their tissues, and release oxygen into the air. That is why maintaining forests and even expanding vegetation cover contributes to reducing air pollution.

Green roofs

In cities, in addition to wooded parks, an alternative is green roofs that help regulate the local climate by providing oxygen and purifying the air.

Air pollution in Mexico, Peru, Colombia, and Venezuela

- Mexico

In 2018, Mexico was located at number 33 in the list of the World Air Quality Report (includes 73 countries), being the third country in Latin America. This list is based on PM2.5 concentrations (µg / m³).

On the other hand, of the 15 cities with the highest air pollution in Latin America, five are in Mexico and the one with the highest pollution is Mexico City.

It is estimated that air pollution causes the premature death of between 40,000 and 50,000 people each year in Mexico.

Surveillance system

Although there are monitoring systems in 21 states of the country, only 16 report data in at least one station. With the exception of Mexico City, which has records since 1986, access to data in the other locations is limited.

Mexico City

Mexico City in 1992 earned the reputation of being the most air-polluted city in the world. The World Health Organization declared this city as the second in concentrations of nitrogen dioxide between 2002 and 2005.

Air pollution in Mexico City. Source: Menemix

However, due to some measures taken for 2018, it appears as the third in Latin America with the worst air quality (at the moderate level). However, the metropolitan areas of the Valley of Mexico continue to have serious pollution problems due to nitrogen dioxide and ozone.

- Peru

Surveillance system

The Lima metropolitan area has 10 automated sampling stations for the monitoring and control of air quality.

Material particles

In 2018, the World Air Quality Report indicated that Peru was the country with the highest air pollution in Latin America in PM2.5 and number 14 worldwide. In Lima in 2001-2011 an average of approximately 50 ug / m3 of PM2.5 was detected when the level recommended by the WHO is 10 ug / m3.

In 2019, Lima presents PM10 levels above 80 and 100 ug / m3 in some monitoring stations. These levels are considered excessively high by the standards of the World Health Organization.

Mining

In Peru, mining releases various toxic substances into the air, especially heavy metals. These include atmospheric arsenic, lead, cadmium, copper, zinc, and sulfur dioxide.

Samples have been carried out in the city of La Oroya that have confirmed the lead contamination of its entire population.

Other studies in various communities in the mining city of Cerro de Pasco showed heavy metal poisoning. 53% of children and approximately 9% of women had blood lead levels above 10 ug / dL.

Automotive pollution

Lima is considered one of the Latin American capitals with the most automotive pollution. In this city the measurements give levels above those allowed by the WHO for sulfur dioxide, nitrogen dioxide and suspended particles.

The main cause appears to be automobile traffic combined with the climatic conditions in the area. In 2018 World Air Quality Report places Lima as the second capital city with the worst air quality in Latin America (moderate level).

- Colombia

Surveillance system

This country has an Air Quality Surveillance System that includes 170 monitoring stations. The most relevant pollutants for the authorities of this country are PM10, SO2, NO4, O ·, PST and PM2.5, in order of attention.

Material particles

The main cause of air pollution in this country is the burning of fossil fuels. Colombia is ranked 50th in the 2018 World Air Quality Report, being the fifth in Latin America with the highest concentrations of PM2.5.

One of the most worrying pollutants are PM10, given its high concentrations and proven effect on the health of the sensitive population. In cities such as Bogotá and Cúcuta, PM10 concentrations exceeded the permitted limit in the evaluations carried out from 2007 to 2010.

Polluting gases

The levels of nitrogen oxides and sulfur remain within permissible ranges and ozone at ground level exceeds critical levels in urban areas. Tropospheric ozone is the second most worrying pollutant in Colombia.

- Venezuela

Surveillance system

The main air pollution indicators considered are PTS, PM10 and lead (Pb) concentrations. Monitoring is carried out in 22 stations in the cities of Caracas, Maracay, Valencia, Barquisimeto, San Cristóbal, Maracaibo and the Barcelona-Puerto La Cruz axis.

In addition, the Venezuelan Corporation of Guayana has 10 stations in the city of Puerto Ordaz, a center for the mining-metallurgical industry. As well as the state oil company PDVSA has 11 stations located in its refineries and cryogenic complexes.

Motor vehicles

Experts warn about the increase in air pollution in the main urban centers. This is mainly the result of emissions from automobiles and companies whose monitoring and control systems appear to have weakened.

Oil industry

In the oil and petrochemical industry, preventive or corrective maintenance plans do not work, which poses serious pollution problems. An example of this is the atmospheric pollutant emissions in the El Tablazo and Jose petrochemical complexes.

Urban pollution

The concentration of total suspended particles (PTS) for 2008 was a national urban average of 35 µg / m3. The national standard establishes the maximum PTS limit at 75 µg / m3, so these values ​​are within the acceptable parameters.

As for PM10, in 2009 they stood at 37 µg / m3, showing an increase for 2010 where they exceed 50 µg / m3. These values ​​are well above the maximum allowed limit of 20 µg / m3 established by the World Health Organization.

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