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Air pollutants: Volatile Organic Compounds

What are volatile organic compounds?

Volatile organic compounds, also known as VOCs, are organic chemical compounds with a high volatility under normal atmospheric temperature and pressure conditions. In other words, these organic compounds evaporate or sublimate easily at ordinary room temperature from materials and even organisms at low boiling points (according to experts definition, less than or equal to 250°C).

Any compound of carbon participating in atmospheric photochemical reactions is considered a VOC, excluding carbon monoxide, carbon dioxide, carbonic acid, metallic carbides (or carbonates) and ammonium carbonate.

volatile organic compounds

Volatile organic compounds list

VOCs are numerous, varied and ubiquitous, both human-made and naturally occurring. For instance, most commonly found VOCs are:

  • Acetone CH3(CO)CH3
  • Benzene C6H6
  • Ethylene glycol C2H6O2
  • Formaldehyde CH2O
  • Methylene chloride CH2Cl2
  • Perchloroethylene C2Cl4
  • Toluene C7H8
  • Xylene C8H10
  • Trichloroethylene C2HCl3

VOCs classification

According to the World Health Organization (WHO), volatile organic compounds are categorized in the following:

  • Very volatile organic compounds (VVOCs): with a boiling point range from 0 to 50-100°C. Some examples are propane, butane or methyl chloride.
  • Volatile organic compounds (VOCs): having boiling points between 50-100 and 240-260°C. Examples of VOCs are toluene, ethanol, acetone or hexanal.
  • Semi-volatile organic compounds (SVOCs): boiling point from 240-260 to 380-400°C, the most typical compounds are pesticides or fire retardants.  

Volatile organic compounds sources

VOCs can be generated both biologically and anthropogenically. While anthropogenic sources emit about 142 teragrams of carbon per year as VOCs, biological sources produce about 1150 teragrams.

Plants are major producers of volatile organic compounds, but the emissions depend on some factors, such as sunlight (that determines biosynthesis rates) and temperature (that determines volatilization and growth). Plants eject all these emissions using their leaves, specifically the stomata.

We have many products at home that release or “off-gas” VOCs. Some examples of anthropogenic sources are: carpets, adhesives, composite wood products, paints, varnishes, air fresheners, cleaning and disinfecting chemicals, newspapers, non-electric space heaters, photocopiers, smoking, cosmetics, refrigerants, pesticides, gasoline or exhaust from cars, among many others.

VOCs in paint

Paints and protective coating are human-made major sources of VOCs, a disturbing fact giving that over 12 billion litres of paints are produced every year.

Currently, the United States Environmental Protection Agency (EPA) has constrained VOC content on paints at 250 grams per liter for flat coatings and 380 g/l for other coatings (such as low-luster or semi gloss). However, some states have adopted toughest measures, for instance California, with a limit of 50 g/l for all finishes.

vocs in paint

However, how long do VOCs last after painting? It depends on several factors: if these are outdoors or indoors, temperature, paint’s concentration of VOC content, house airflow, volume of the room or space, etc. For these reasons, measurement methods for VOCs indoors are not accurate and have led to several misunderstanding and criticism, as not everybody knows you need an expert to properly analyze it.

Since it is difficult to know the real exposure of VOCs, it is recommended using no or low VOC paints. To be considered VOC-free (or zero-VOC), it cannot contain more than 5 g/l of VOCs. These eco paints are the best solutions to prevent air pollution from VOCs.

VOCs health and environmental effects

VOCs are also well-known carcinogens since these are found 2 to 5 times more indoors than outdoors, especially man-made VOCs that are the origin for some allergies and respiratory problems. Volatile organic compounds main health effects are:

  • Eye, nose and throat irritation
  • Headaches, loss of coordination and nauseas
  • Damage the liver, kidneys and the central nervous system.
  • Some organics can cause cancer in animals and some others are suspected or known to cause cancer in humans.

nose irritation

Since the inhalation of VOCs usually takes place indoors, short-term exposure can quickly drive to symptoms like conjunctival irritation, nose and throat discomfort, headache, allergic skin reaction, dyspnea, declines in serum cholinesterase levels, nausea, vomiting, nose bleeding, fatigue and dizziness.

VOCs are not considered criteria pollutants by themselves, but are an important part of Ozone’s creation, both tropospheric and ground-level. For this reason, these are not considered  criteria pollutants, as VOCs have not a direct impact on the environment.

However, VOCs indirectly produce smog by reactions between ozone (created by the combination with NOx, heat and sunlight) and other compounds, which can really damage the environment and threat humans lives.

What can you do to protect yourself?

Volatile organic compounds can be detected using VOC sensors. These electronic devices identify ppm concentrations based on interactions between the organic compounds and the sensor components. However, the sensitivity and selectivity of the device depends on the molecular structure of the VOC and its concentration.

air purifier

Other methods to protect yourself are devices such as air purifiers for VOCs. Moreover, to protect yourself from VOCs you can make changes in your alimentation routines, like organic gardening food and starting to eat healthy grown vegetables and fruits without usage of synthetic fertilizers, pesticides, herbicides, etc.

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Air pollutants: Sulfur Dioxide

What is sulfur dioxide?

Sulfur dioxide (sulphur dioxide in British English) is the greatest concern for the larger group of gaseous sulfur oxides (SOx). All standards and control measures for SO2 include all sulfur oxides, as sulfur dioxide is used as the indicator due to it has a major presence in the air.

Its chemical formula is SO2, it is invisible and has a nasty, pungent, irritating and sharp smell. Sulfur dioxide easily reacts with other substances to form harmful compounds, such as sulfuric acid, sulfurous acid and sulfate particles.

Sulfur dioxide is used in a big variety of situations, for example:

  • To produce acid sulfuric, through a method called contact process.
  • To preserve dried apricots, figs or other fruits.
  • Used as an antibiotic and antioxidant in winemaking.
  • To decolorize substances like swimming pool water, where the blue color of chlorine is removed.

Despite it is a toxic gas, sulfur dioxide is used in many more situations and it has a huge presence in our daily lives.

Sulfur dioxide sources

About 99% of sulfur dioxide emissions are produced by industrial activities, such as generation of electricity from coal, oil or gas. It is also produced in the burning of fossil fuels on industrial facilities, by the extraction of metal from ore or by vehicles such as cars, ships or locomotives that burn fuel.

Naturally, SO2 is formed by volcanic eruptions in active volcanoes. However, it is interesting to know there is a high presence of SO2 emissions on Venus, Mars and Jupiter, being one of the most significant gases in those atmospheres.

volcanic emissions

What are the health and environmental effects of sulfur dioxide pollution?

Sulfur dioxide, as well as the others sulfur oxides, have huge impact on the environment and dangerously affect humans, both quite similarly to what other criteria pollutants do.

How SO2 can affect humans health?

Sulfur dioxide is such a toxic gas that you can feel the firsts symptoms just 10 to 15 minutes after breathing it. Short-term exposure causes problems to the respiratory system, such as breathing difficulties, nose and throat irritating, coughing, wheezing and shortness of breath.

Sensitive groups such as elderly, children or asthmatics will notice strongest symptoms and effects. They are also more susceptible to develop diseases, in case they do not have them yet.

High concentrations of SO2 in the atmosphere commonly create other SOx, which react at the same time with other compounds to form small air pollution particles (PM). As a result, long-term exposure can seriously damage your lungs since particulate matter can penetrate deeply into our organisms.  

Since one of its uses is to preserve food, bad production process could provoke poisoning due to sulfur dioxide ingestion. Be careful when you buy it!

Which is sulfur dioxide pollution impact on environment?

This series of events and reactions from sulfur dioxide and other sulfur oxides to create particulate matter may drive to reduce the visibility in open spaces and produce haze. The deposition of these particles may damage stones, buildings, statues and monuments.

High concentrations of SOx can be harmful for vegetation foliage and growth, and can contribute to acid rain formation, which causes several issues on sensitive ecosystems.

plants problems because sulfur dioxide emissions

What is being done to reduce sulfur dioxide pollution?

Over the years, developed countries have reached some agreements to control pollution. Each country or state has its own implementation plan. For example, the Clean Air Act made by the U.S. Environmental Protection Agency (EPA) establishes National Ambient Air Quality Standards (NAAQS) for those criteria pollutants considered most harmful for health and the environment. Another example is the European Union Air Quality Directive by the European Environmental Agency, which also establishes some standards and tips to reduce air pollution, both indoors and outdoors.

Sulfur dioxide, thanks to its high toxicity and danger for humans and environment, is considered both a primary and secondary criteria pollutant. Maximum permitted or recommended levels for SO2 are:

  • It has not World Health Organization (WHO) guidelines in the last edition.
  • NAAQS: 75 ppb per hour and 0.5 ppm (1,300 μg/m³) every 3 hours (which cannot be exceeded more than once per year).
  • EU Air Quality Directive: 250 μg/m³ each hour and 125 μg/m³ daily, what cannot be exceeded more than 24 and 3 times per year respectively.
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Air pollutants: Particulate Matter

What is particulate matter?

Particle pollution, also called particulate matter (PM), atmospheric aerosol particles or suspended particulate matter (SPM), is defined as microscopic solid (almost always) or liquid materials floating in the air.

particulate matter

Types of particulate matter

Those airborne particles can be divided in suspended particulate matter, thoracic particles, respirable particles, inhalable coarse particles and soot. Inhalable coarse particles can also be classified depending on their size as:

  • Coarse Particles (PM10): aerodynamic diameter from 2.5 to 10 micrometers (µm). To give you an idea, its size is like 1/5 part from a human hair or 1/9 part from a fine beach sand particulate.
  • Fine Particles (PM2.5): 2.5 µm or smaller. For example, it is as little as 1 part from 20 of a human hair, so it is obvious that these particulates can only be seen with an electron microscope.
  • Ultra fine particles (UFPs): less than 100 nanometres (nm). Since they are far smaller, there is no regulation for this size class, even though these are considered to have more severe health impact than the others.

Sources and composition of particulate matter

The composition of particles depends on its origin and formation. Aerosols can occur naturally or artificially.

Aerosols

Most common natural aerosols are pollen or fog, although other natural sources can be volcanoes, sand storms, forest and grassland fires, living vegetation and sea spray.

Human activities such as the burning of fossil fuels, different industrial activities and power plants contribute to produce a significant amount of artificial aerosols. Haze, dust, smoke are just some examples, but there are many more particulate air pollutants.

Since there is a wide range of aerosols’ compositions, here you have summarized some examples:

  • Mineral dust: made of mineral oxides blown from Earth’s crust.
  • Sea salt: originated from sea spray and composed by sodium chloride.
  • Sulfuric acid and nitric acid: generated in the oxidation of primary gases such as sulfur and nitrogen oxides.
  • Organic Matter (OM): deriving from the oxidation of VOCs.

What are the health and environmental effects of particle pollution?

Their capacity to penetrate deeply into your lungs makes particulate matter one of the criteria pollutants to control in order to protect humans’ wellness and health. The smaller the particle is, the more harmful it can be for the organism. This is why particulate matter have different degrees according to its penetration capability into the cardiovascular system:

  • Inhalable particles: can penetrate into the bronchi and are filtered by the cilia.
  • Thoracic particles: can reach easily the bronchioles.
  • Respirable particles: if thoracic particles can even pass throw the alveoli until the bloodstream, then are considered respirable particles.

respiratory diseases

All those particles have effects on humans health, damaging your lungs and your circulatory system. The most common long-term health effects caused by the inhalation of particulate matter are: asthma, lung cancer, reduced lung function, respiratory diseases, cardiovascular diseases, premature delivery and birth defects (such as low birth weight and premature death).

Exposure to fine particles in the short-term can cause coughing, sneezing, runny nose, shortness of breath and eye, nose, throat and lung irritation.

Huge concentrations of particles in the air can lead to haze creation or difficulties in the photosynthesis functions of plants. Furthermore, depending on their composition they can react with other compounds to create other harmful gases for the environment or and the people.

How is particulate matter air pollution controlled?

Over the years, developed countries have reached some agreements to control pollution. Each country or state has its own implementation plan. For example, the Clean Air Act made by the U.S. Environmental Protection Agency (EPA) establishes National Ambient Air Quality Standards (NAAQS) for those criteria pollutants considered most harmful for health and the environment. Another example is the European Union Air Quality Directive by the European Environmental Agency, which also establishes some standards and tips to reduce air pollution, both indoors and outdoors.

Both sizes of particulate matter, PM10 and PM2.5, are classified as a primary and secondary criteria pollutants since it can be extremely harmful for all living beings. Maximum permitted or recommended levels for PM are:

  • In PM2.5:
    • World Health Organization (WHO) guidelines: 25 μg/m³ per day (which cannot be exceeded more than 3 days/year) and 10 μg/m³ per year.
    • NAAQS: maximum concentration of 35 μg/m³ daily and annual mean of 12 μg/m³.
    • EU Air Quality Directive: only monitoring annual concentration, which cannot be higher than 25 μg/m³.
  • In PM10:
    • World Health Organization (WHO) guidelines: 50 μg/m³ per day (which cannot be exceeded more than 3 days/year) and 20 μg/m³ per year.
    • NAAQS: 150 μg/m³ and can only be exceeded more than once per year on average over 3 years.
    • EU Air Quality Directive: cannot exceed more than 35 times annually the concentration of 50 μg/m³ every 24 hours. There is also a maximum of 40 μg/m³ per year.
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Air pollutants: Ozone

What is Ozone?

The Ozone, also known as trioxygen, is a molecule composed of three atoms of oxygen (with the chemical formula O3). It is protecting us from UV radiation through the Ozone Shield (or also Ozone Layer).

ozone layer protection

However, if the ozone is found on surface-level, it can become a harmful gas that can cause serious health issues when inhaled in high concentrations. For this reason, Ozone (O3) is divided into “Good Ozone” (Ozone Shield) and  “Bad Ozone” (Ground-Level Ozone).

“Good” vs “Bad” Ozone

Good Ozone: The ozone layer

Good Ozone is created naturally in the upper atmosphere (at 20 km to 30 km above Earth), reason why it is called stratospheric ozone. It forms the well-known ozone layer, which serves as the Earth’s shield to protect us from solar ultraviolet radiation. Moreover, it is considered one of the primary greenhouse gases in the atmosphere.

Since the beginning of the Industrial Revolution, the emissions of carbon dioxide to the atmosphere have substantially increased. These activities have partially destroyed this protection layer and leaded to the ozone layer depletion, commonly known as “the ozone hole”.

Bad Ozone: Ground-level ozone

Bad Ozone (also named ground-level ozone or tropospheric ozone) is a toxic gas composed of a combination of gases and sunlight. The ozone formation formula is: VOCs + NOx + Heat + Sunlight = O3.

It easily reacts with some hydrocarbons, being the main component for smog, which causes severe sickness or even death.

This ground-level ozone is considered a criteria air pollutant due to its toxicity to humans and the environment. In order to control it and protect population, several air pollution standards involving ozone have been established worldwide.  

Ozone does not only have effects on urban environments, as wind can make it travel long distances, affecting rural areas as well. Furthermore, Ozone can also be formed inside houses by electronic devices. For instance, there are many “air purifiers” which generate ozone as a way to destroy other harmful pollutants. Indoor air pollution can become so dangerous for humans’ health if it is not detected and solved on time. Ozone reacts with organic materials in the same way it does with other gases to create smog, altering the chemical compositions around us.

smog due to ozone

What are the health and environmental effects of ozone?

As it has been said, ground-level ozone can cause a variety of respiratory health effects. It affects on greater way sensitive groups such as elderly, children or people of all ages who have sensitive lungs. However, breathing high concentrations of ozone is very dangerous for everyone.

Short-term exposure can cause a variety of respiratory health effects, including chest pain, coughing, throat irritation, and airway inflammation. It also can reduce lung function and harm lung tissue or decrease the capacity to perform exercise by the shortness of breath. Moreover, ozone has been linked with premature mortality or worsening respiratory illnesses like bronchitis, asthma or emphysema.

On the other side, many studies have proven that long-term ozone exposure can provoke asthma, damage lung tissue for life and increase the risk of death from respiratory causes.

Ozone can significantly damage vegetations and ecosystems. During growing season, when these are more sensitive, it causes photosynthesis reduction, slowing plants’ growth and increasing the risk of disease, insects, heavy weather conditions or other pollutants’ effects. It can be also related with heat waves since plants absorb less ozone and its concentration rises.

heat wave

How is ozone pollution controlled?

Over the years, developed countries have reached some agreements to control pollution. Each country or state has its own implementation plan. For example, the Clean Air Act made by the U.S. Environmental Protection Agency (EPA) establishes National Ambient Air Quality Standards (NAAQS) for those criteria pollutants considered most harmful for health and the environment. Another example is the European Union Air Quality Directive by the European Environmental Agency, which also establishes some standards and tips to reduce air pollution, both indoors and outdoors.

Ozone, especially ground-level ozone, is considered both a primary and secondary criteria pollutant. As already mentioned, it can become a huge issue for the environment and for humans health. Maximum permitted or recommended levels for O3 are:

  • World Health Organization (WHO) guidelines: 0,070 ppm (140 μg/m³) for annual fourth-highest daily maximum 8-hour concentration, averaged over 3 years.
  • NAAQS: In addition to WHO guidelines, in USA ozone is also monitored each hour with a maximum concentration of 0.12 ppm (235 μg/m³).
  • EU Air Quality Directive: maximum daily 8-hour mean of 120 μg/m³, which cannot be exceeded more than 25 days over 3 years.
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Air pollutants: Nitrogen Dioxide

What’s nitrogen dioxide?

burning of fossil fuels

Nitrogen Dioxide is a chemical compound with the formula NO2, but it is usually defined as an indicator for a highly reactive gases group known as oxides of nitrogen or nitrogen oxides (NOx).

Its smell and color are the only properties of nitrogen dioxide perceptible for humans without any special equipment. NO2 has a biting and pungent odor and it is easily recognizable with a red-brown color at gas stage (over 21.2 °C) and yellow-brown looking at liquid’s (between 21.2 and -11.2 °C).

Nitrogen dioxide uses

Nitrogen dioxide is released in wide variety of situations and processes that involve nitrogen. Here are some examples:

  • Nitric acid manufacturing.
  • Nitrating agent in chemical explosives manufacturing.
  • Room temperature sterilization agent.
  • Oxidizing rockets fuel.
  • Polymerization inhibitor for acrylates.

Sources of nitrogen dioxide pollution

Nitrogen dioxide emissions to the atmosphere are processes that contribute to worsen the air quality, and this is the reason why it is considered criteria pollutant. Nitrogen oxides are produced by human activity 99% of the time, and produced naturally the other 1% during thunderstorms by electric discharge.

Outdoors, cars and combustion engines burning fossil fuels are the number one responsible for nitrogen dioxide emissions. Indoors, NO2 emissions are mainly produced by sources like cigarettes, butane, kerosene heaters and stoves.

traffic jam

Indirectly, nitrogen monoxide emissions also contribute to the formation of nitrogen dioxide since the first reacts with oxygen or ozone to produce the second.

Nitrogen dioxide health and environmental effects

As indicator of the NOx group, nitrogen dioxide is responsible for several health and environmental effects. NO2 reacts with other gases to create adverse meteorological conditions, such as acid rain or ground-level ozone, known for being a threat to humans and wildlife.

Health effects on humans

Nitrogen dioxide, as well as its NOx siblings, lead to respiratory problems when inhaled since they can penetrate deeply into sensitive lung tissue. Some symptoms are coughing, wheezing or difficulties to breathe.

However, these nitrogen oxides need to react with other compounds like ammonia, volatile organic compounds (VOCs) or common organic chemicals to become extremely harmful, causing then similar health effects than NO2.

Long-term exposure could carry the development of asthma, emphysema, bronchitis or other respiratory diseases and infections. It can also aggravate cardiovascular problems such as heart diseases. Moreover, in extreme conditions, breathing polluted air with high levels of nitrogen dioxide may even cause premature death.

Sensitive groups such as children, elderly or people with respiratory problems are more affected by the exposure to this pollutant. For these groups, it is recommended controlling NOx levels and emissions, especially for NO2 and NO, with devices such as nitrogen dioxide detectors (that can even be portables).

How does nitrogen dioxide pollution affect our planet?

Nitrogen dioxide’s main partner in the NOx group is nitric oxide or nitrogen monoxide (NO). As already said, both help in the development of environmental effects like smog, acid rain or tropospheric ozone.

Nitrogen dioxide or any others NOx react with water, oxygen and other chemicals in the atmosphere to form acid rain. Acid rain damages vegetation, buildings, water bodies and all the living beings on these environments.

Despite nitrogen is essential for plants nutrition, high levels of nitrogen dioxide or nitrogen monoxide may damage their lives. Nitrogen oxides in the atmosphere contribute to nutrient pollution in coastal waters and nitrate particles affect the visibility and create hazy air.

How is NO2 pollution controlled?

Over the years, developed countries have reached some agreements to control pollution. Each country or state has its own implementation plan. For example, the Clean Air Act made by the U.S. Environmental Protection Agency (EPA) establishes National Ambient Air Quality Standards (NAAQS) for those criteria pollutants considered most harmful for health and the environment. Another example is the European Union Air Quality Directive by the European Environmental Agency, which also establishes some standards and tips to reduce air pollution, both indoors and outdoors.

Nitrogen dioxide is considered both a primary and secondary criteria pollutant, as it can be extremely dangerous for the environment and the public safety. As mentioned, it acts as the indicator for the nitrogen oxides group, and the maximum permitted or recommended levels for NO2 are:

  • World Health Organization (WHO) guidelines: 200 μg/m³ and 40 μg/m³ for an average periods of 1 hour and 1 year, respectively.
  • NAAQS: 0,1 ppm of 1-hour daily maximum concentrations, averaged over 3 years, while annual mean cannot exceed 0,053 ppm (100 μg/m³).

EU Air Quality Directive: exactly the same as WHO guidelines, 200 μg/m³ for 1 hour (cannot be exceeded more than 18 times per year) and 40 μg/m³ annually.

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Air pollutants: Lead

What is lead pollution?

Lead (Pb) is a naturally occurring heavy metal that is found in the Earth’s crust. It is denser than most common materials, soft, malleable and has a low melting point. This capability to change easily the state from solid to liquid at atmospheric pressure is favouring its facility of being introduced as an air pollutant into the atmosphere.

lead

How does lead get into the air?

Major sources of lead in the air are mining, metal manufacturing and piston-engine aircraft operating on leaded aviation fuel. Other sources of lead air pollution are industrial productions, waste incineration, recycling, mobilization of previously buried lead, utilities and lead-acid battery manufacturers.

Peak of lead emissions to the atmosphere had place during Industrial Revolution and with the usage of leaded gasoline during the last decades of the 20th century. Nowadays, high lead emissions still have place, especially in developing countries where industrial emissions arising from coal burning prevail.

lead manufacture

What are the environmental and health effects of lead pollution?

Lead has not as much influence on the environment as other pollutants, but it can have a noticeable impact on plants. Lead accumulate on soils for a long time (hundreds or even thousands of years) and also can combine with other metals to inhibit photosynthesis. At high lead pollution levels, plants growth and survival may suffer adverse effects and can cause neurological problems to vertebrates.

Lead air pollution health effects on humans usually are neurological effects in children and cardiovascular effects (high blood pressure and heart disease, for example) in adults.

Lead exposure on humans can be very harmful, involving almost every organ and system in the human body. Once it is inhaled, lead is placed on the bloodstream and bones driving to a possible case of lead poisoning.  

cardiovascular problems

Lead poisoning: symptoms and treatment

Apart from air pollution, lead poisoning come from different sources, such as water, dust, food or consumer products. The effects it may cause to each individual depends on the levels and the time exposure to the pollutant.

Some lead poisoning symptoms or signs that could indicate you are in danger are: headache, intermittent abdominal pain, loss of appetite, nausea, diarrhea, constipation, memory loss, kidney failure, male reproductive problems, depression, weakness, pain or tingling in the extremities and muscles.

In children, lead poisoning is prone to cause similar symptoms: loss of appetite, abdominal pain, vomiting, weight loss, constipation, anemia, kidney failure, irritability, lethargy, learning disabilities and behavioral problems. Others such as slow development of normal childhood behaviors (like the usage of words and talking) and permanent neurological problems (like learning deficits and lowered IQ) are also commonly diagnosticated to this segment. During the pregnancy, breathing lead polluted air may increase the risk of premature birth or low birth weight.

According to the level of poisoning and what part of your organism is affected, treatments may change. We will have a look to lead poisoning treatments due to air pollution.

When lead levels are high on blood, lead intoxication can be treated with chelation therapy or treatment of iron, calcium and zinc deficiencies, as these are treatments related to lead absorption.

How is lead air pollution controlled?

Over the years, developed countries have reached some agreements to control pollution. Each country or state has its own implementation plan. For example, the Clean Air Act made by the U.S. Environmental Protection Agency (EPA) establishes National Ambient Air Quality Standards (NAAQS) for those criteria pollutants considered most harmful for health and the environment. Another example is the European Union Air Quality Directive by the European Environmental Agency, which also establishes some standards and tips to reduce air pollution, both indoors and outdoors.

Lead is considered both a primary and a secondary criteria pollutant due to its effects either on public health and the environment. Maximum permitted or recommended levels of lead in the air are:

  • Nothing is included in the World Health Organization (WHO) guidelines.
  • NAAQS: cannot exceed 0,15 μg/m³ for 3 months average.
  • EU Air Quality Directive: cannot exceed 0,5 μg/m³ over a year.
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Air pollutants: Carbon Monoxide

What is carbon monoxide?

Carbon Monoxide (CO) is an odorless, tasteless and colorless toxic gas, dangerous for humans and wildlife in higher concentrations than 35 ppm. Carbon monoxide composition is made of one carbon atom and one oxygen atom. It plays an important role in smog formation since it can react to create ground-level ozone.

carbon monoxide

What causes carbon monoxide?

Carbon monoxide is the result of an incomplete burning of organic matter. It is naturally produced in big amounts in the troposphere. Likewise, it can also be generated by volcanoes, forest fires, and other natural combustion processes.

burning organic matter

Man-made activities also emit tons of CO, in fact we are the main cause for CO emissions. For example, cars with internal combustion engines and without catalytic converters are huge generators of carbon monoxide. Even if they have catalytic converters, the first 90 seconds after turning on the engine will produce from 10.000 to 30.000 ppm of CO.

Other carbon monoxide human sources are heaters or cooking equipment that runs on carbon-based fuels. These fuels include furnaces, gas ovens, gas water heaters, gas room heaters, kerosene room heaters, charcoal BBQs, portable generators fireplaces, among a lot more.

gas heat

Carbon monoxide pollution health effects

You go to work and turn on your car’s engine inside your garage. The emissions of CO produced during the ignition will instantly pollute the air you are breathing indoors. Even with the door open, this polluted air will probably reach higher levels than 100 ppm and, as soon as the garage door is closed, it will scatter all over the building.

Indoors and outdoors, breathing high concentrations of CO reduces the amount of oxygen transported in the bloodstream. This can increase the probability of carbon monoxide poisoning in critical organs like the heart or the brain.

Carbon monoxide poisoning: symptoms, treatment and prevention

Carbon monoxide cannot be detected by humans naturally, and special equipment is used to measure it. However, there are a few symptoms that can help you identify carbon monoxide poisoning.

Symptoms are often described as similar to flu. Most common are weakness, headache, dizziness, confusion, chest pain, fatigue, nausea or even death. Long-term exposure to carbon monoxide can produce memory loss, feeling tired or movement problems. Continued and constant CO exposure over the time may cause chronic poisoning, making you feel the mentioned symptoms for life.

flu

Except from extreme cases, carbon monoxide poisoning can be solved just by moving to a non polluted area and breath, instantly pushing the pollutant out and substituting it by oxygen. However, if somebody needs treatment, he will use non-rebreather masks, which administer oxygen. In extreme cases the person can also be placed inside a hyperbaric oxygen chamber.

As mentioned, we cannot detect CO by ourselves without any special equipment. That is why it is important and recommended by governments to install carbon monoxide detectors or alarms at home, used to measure CO levels overtime. These warn in case concentrations are getting dangerous and may cause a public health issue, recommending to evacuate or air out the area.

Effects of carbon monoxide on environment

Carbon monoxide is different from other pollutants since it has not a direct impact on the environment and it can persist over a month in the atmosphere. Although considered a greenhouse gas, it contributes indirectly to climate change. Its presence affects concentrations of other greenhouse gases like methane, tropospheric ozone and carbon dioxide, creating particles and other harmful pollutants.

climate change

How is carbon monoxide pollution controlled?

Over the years, developed countries have reached some agreements to control pollution. Each country or state has its own implementation plan. For example, the Clean Air Act made by the U.S. Environmental Protection Agency (EPA) establishes National Ambient Air Quality Standards (NAAQS) for those criteria pollutants considered most harmful for health and the environment. Another example is the European Union Air Quality Directive by the European Environmental Agency, which also establishes some standards and tips to reduce air pollution, both indoors and outdoors.

Since CO is a primary criteria pollutant due to its effects on human health and public safety, maximum permitted or recommended levels for carbon monoxide are:

  • Nothing is included in the World Health Organization (WHO) guidelines.
  • NAAQS: 35 ppm (40 μg/m³) for 1 hour exposure and 9 ppm (10 μg/m³) for 8 hours.
  • EU Air Quality Directive: 10 mg/m³ for a maximum of  8 hour daily exposure.