What is smog?
Smog is an air pollution phenomenon that can be defined as the combination of various gases with dust and water vapor. In other words, smog is a yellowish or blackish fog composed of nitrogen oxides, sulphur oxides, ozone, smoke and dirt particles. This kind of visible air pollution was originally named in the early 20th century as a mixture of the words smoke and fog.
Types of smog
Depending on its origin and composition, there are 3 types of smog:
- Volcanic smog is composed by oxygen, moisture, sunlight, particles and gases released from a volcano eruption. This type of smog is commonly seen in the Hawaiian Islands, as the Kilauea volcano has been erupting every day since 1983.
- Photochemical smog is the most popular kind of smog nowadays. It is formed by nitrogen oxide, hydrocarbons and sunlight.
- Sulfurous smog is originated when a high concentration of sulfur oxides are released into the atmosphere. It is also known as “London smog”, place where it is prevalent.
What causes smog?
Smog is formed when gases (for instance, ground-level ozone) and airborne particles react in the air with heat and sunlight.
Some of these pollution gases, called precursors, drive to ground-level ozone and particle formation, thanks to a sequence of photochemical reactions. Precursors gases are: volatile organic compounds (VOC), sulphur dioxide (SO2) and nitrogen oxides (NOx).
Apart from vehicles exhaust systems and its combustion of fossil fuels, smog-creation gases are also produced by coal fires and volcano eruptions.
However, smog usually appears in dense traffic situations and with optimal weather conditions to chemically react: high temperatures, calm winds and sunshine.
How smog affects the environment and humans health?
Since smog is composed by very tiny particles and gases, it can penetrate deeply into our bodies, specifically into the lungs of both animals and humans. A lot of species and green life are killed by smog due to the few adaptability to breathe purely in such toxic environments.
Smog exposure can drive to respiration problems such as breathing passages, decrease lungs working capacity, shortness of breath, pain when inhaling deeply, wheezing and coughing. Other respiratory issues or illnesses also related to smog are pneumonia, cold, chest pain, inflammation in lungs tissues or even premature death due to cancer or unknown respiratory diseases.
Eye and nose irritation are usual symptoms of smog exposure, drying out the protective throat and nose membranes and interfering with the body’s ability to fight infection and possible illness.
Furthermore, some studies have proven it also can drive to increase alzheimer probability, low birth weight or other birth risks. Hospital admissions and respiratory deaths often increase during periods when ozone levels are high. Moreover, smog can cause visibility problems for drivers and thus increase the danger of having a car accident.
Sensitive groups can suffer more intense symptoms and effects, this is why it is recommended for them to avoid any kind of exposure. This group at greater risks is formed by elderly, children and people with respiratory or heart problems, such as asthma, bronchitis or emphysema.
Levels of unhealthy exposure
Ozone is the most risky air pollutant in smog. According to the U.S. Environmental Protection Agency (EPA) and its Air Quality Index, 8 hour average ozone concentrations can be classified as:
- Unhealthy for sensitive groups: 85 to 104 ppbv
- Unhealthy: 105 to 124 ppbv
- Very unhealthy: 125 to 404 ppbv
On the other hand, smog can cause harmful effects to the vegetation and the environment as well, denying plant growth, damaging forests, crops and vegetables, such as soybeans, wheat, tomatoes, peanuts and cotton.
What you can do to prevent smog?
When smog appears, you can only protect yourself with a face mask or staying indoors. To avoid these situations you can embrace some practices in order to prevent smog formation:
- Change your car habits:
- Drive less to cut down emissions.
- Maintain your car to make it work properly.
- Fuel up in cooler temperatures.
- Purchase a hybrid or electric vehicle.
- Change your consumption habits:
- Avoid high VOC products, not only for smog prevention but also to have a good air quality indoors.
- Avoid gas-powered yard equipment.
- Buy local to reduce transport emissions.
- Be energy efficient in your home.
- Taking a stand:
- Don’t support organizations that have poor environmental practices.
- Promote your stance and what are you doing to solve the problem with your closest family and friends and even in Social Media.
- Contact local politicians and business leaders.
Areas affected by smog
Smog is not only taking place in particular places, it can be formed wherever pollutants are emitted and in other areas where pollution has been transported by wind flowing.
However, there are some cities or places where smog is usual and can become a real nightmare for inhabitants:
- Delhi, India
- Beijing, China
- London and other areas in the United Kingdom
- Mexico City, Mexico
- Santiago, Chile
- Tehran, Iran
- Los Angeles and the San Joaquin Valley, United States
- Ulaanbaatar, Mongolia
- Southeast, Asia
The Great Smog of London 1952
Otherwise, the worst case of urban smog happened in London from Friday 5 to Tuesday 9 of December 1952. It was called the Great Smog of London (and the Great Smog of 1952 as well) and it caused more than 4.000 deaths and 100.000 illnesses during that period, most involving respiratory problems. Furthermore, recent studies have proven that over 6.000 people more passed away on the following months.
Among a lot of reasons, it was originated because of low temperatures during that winter, fact that made Londoners burn more coal to warm themselves. Later an anticyclone settled over a windless London, which caused a temperature inversion and favoured smog to be formed and persistent over the city.
What is a smog check?
Smog Check inspections are designed to identify vehicles with excess emissions. For instance, in California (United States), there is a Smog Check Program that has become very popular and it is an important part of the improvements made to control air pollution.
Despite other countries do not have smog tests or stations by themselves, “smog emissions” are checked every time your car gets its circulation license and inspection sheet.