In recent years, smog, its effects, and its causes have become significant challenges in urban environmental management. This is especially true in major cities like Beijing, where air quality fluctuations directly affect citizens’ health and quality of life.
Beijing has experienced smog-free or lightly polluted weather over the past two weeks. However, air pollution remains a recurrent issue, highlighting its complexity and persistence. Scientific forecasting and effective pollution control measures have improved the atmospheric environment in some regions.
For example, temporary measures like alternating license plates and restricting high-pollution vehicles during major events significantly reduced airborne pollutants.
However, data from 2010 to 2014 shows that overall air quality improvement has been slow. This situation necessitates more systematic and long-term solutions. This article explores the causes of smog in China, its harmful effects, and proposes practical solutions to improve air quality and public health.
1. The Chemical Composition of Smog is Extremely Complex
Smog refers to fine particles formed from various pollutant emissions under specific atmospheric conditions. These emissions include gases and particulates such as CO, SO₂, NOₓ, NH₃, VOCs, and PM. Through a series of physical and chemical processes, these particles interact with water vapor, leading to atmospheric extinction phenomena.
The particulates involved in air pollution generally have diameters between 0.01 and 100 μm. PM2.5 refers to atmospheric particulates with an aerodynamic diameter of 2.5 micrometers or less. These are also known as fine particles.
PM2.5 has a complex composition that includes nearly all elements from the periodic table. It involves over 30,000 organic and inorganic compounds, including sulfates, nitrates, ammonium salts, organic compounds, elemental carbon, and heavy metals.
These “small particles” encompass a “big world.” PM2.5 primarily consists of secondary particles formed from the transformation of primary gas emissions. Direct emissions of PM2.5 are minimal.
2. Smog Significantly Impacts Climate, Environment, and Human Health
PM2.5 in smog has a substantial impact, with PM2.5 concentrations even leading to dust storms. Smog negatively affects climate, the environment, and health in the following ways:
- Climate Impact: Increased PM2.5 concentrations may contribute to the rise in extreme weather events. PM2.5 affects the atmospheric radiation balance, causing the ground to cool and the atmosphere to warm. This can severely influence regional and global climate change and potentially exacerbate atmospheric heating effects and extreme weather events.
- Environmental Impact: Fine particulate pollution is one of the world’s significant environmental issues. Since 1975, fine particle concentrations have been rising globally, except in Europe. Increased PM2.5 levels lead to urban acid rain and photochemical smog, reducing atmospheric visibility and hindering air, water, and land transportation.
- Health Impact: Smog has high humidity, which can directly transmit bacteria and viruses. PM2.5, also known as respirable particles, can enter human alveoli and even the bloodstream, directly causing cardiovascular diseases and other health issues.
PM2.5 has a large specific surface area, allowing it to accumulate various heavy metals and organic pollutants. Many of these substances are carcinogenic and genotoxic, posing significant health risks. PM2.5 pollution increases mortality rates among seriously ill and chronic patients, worsens respiratory and heart diseases, alters lung function and structure, and impacts the human immune system.
Studies have consistently shown a positive correlation between air pollution and respiratory disease mortality rates. In recent years, the incidence of lung cancer in Beijing has risen significantly, with an average of 104 new cases diagnosed daily in 2012.
Research in Guangzhou indicates a strong correlation between lung cancer mortality and smog, with a correlation coefficient of up to 0.97 when considering a seven-year lag period.
3. 90% of Smog Originates from Human Economic and Social Activities
Approximately 10% of smog comes from natural emissions. Nearly 90% originates from human activities linked to economic and social actions. Studies show that atmospheric pollutants include organic carbon, elemental carbon, sulfates, nitrates, ammonium salts, dust, and more.
Sulfates, nitrates, and ammonium salts form from chemical reactions involving primary emissions of sulfur dioxide (SO₂), nitrogen oxides (NOₓ), and ammonia (NH₃).
Volatile organic compounds include oil fumes from cooking, hydrocarbon particulates from vehicle exhaust, and nitrogen-enriched compounds from photochemical reactions. These react with large amounts of SO₂ and NOₓ, transforming into secondary organic aerosols. This process produces more toxic fine particulate pollutants.
These are the main components of the photochemical smog in Southern California, USA, in the mid-20th century.
These pollutants are closely related to human production and living activities. Analysis of PM2.5 emission sources in Beijing reveals that coal burning and motor vehicles are the primary contributors.
Research shows that in Beijing, coal burning accounts for 26% of annual PM2.5 emissions, motor vehicles 19%, catering 11%, and industry 10%. During severe smog in January, motor vehicle emissions contributed the most at 25%, followed by coal burning at 19% and external transport at 19%.
In the Beijing-Tianjin-Hebei region, the main sources of pollution are coal burning (34%), motor vehicles (16%), and industry (15%). Additionally, coal burning, chemical industries, and heavy metal smelting in Hebei and Tianjin are significant sources of heavy metal pollution.
The large number of motor vehicles in Beijing leads to increased atmospheric concentrations of NOₓ, which in turn causes simultaneous rises in nitrate levels. High daytime concentrations of NO₂ coincide with high nitrate levels.
However, the harm from motor vehicle NOₓ emissions in Beijing extends beyond the formation of inorganic nitrates, as they also produce a large amount of nitrogen-containing organic particulates. Nitrates formed during the day transform into carcinogenic nitrites at night under high concentrations of SO₂ and sulfates.
4. Smog Can Be Predicted, Warned, and Mitigated in Advance
Tracking and monitoring atmospheric pollutants show low levels during the Beijing Olympics. PM2.5 levels were below 50 μg/m³.
Measures like alternating license plates and restricting high-pollution vehicles can keep PM2.5 levels below 100 μg/m³. Without these restrictions, levels can reach up to 200 μg/m³.An analysis of January’s severe smog event showed that vehicle emissions and coal burning contributed over 100 μg/m³.
These sources accounted for half of the pollutant concentrations at that time.These situations demonstrate that stable conditions can lead to smog formation.
By considering external pollutants, air pollution can be mitigated. Strengthening local pollution control through advance forecasting and warnings is essential.
5. Prevention and Control Recommendations Based on the Causes of Smog Pollution
To effectively combat smog pollution, a multifaceted approach that combines political will, collaboration, and targeted strategies is essential.
Political Insight and Collaborative Approaches
Eradicating smog pollution demands political insight. It requires implementing regional joint prevention and control measures. This approach must break the existing management system where administrative units operate independently.
Successful Regional Models
Successful examples include the European Community’s management of acid rain and air pollution. In Southern California, collaborative measures are used to reduce photochemical air pollution.
Establishing Pollution Control Committees
Consider establishing regional ventures or committees focused on atmospheric pollution control. Designating specific areas as pilot project “special zones” for air pollution prevention and control could be beneficial.
Strengthening Legal Frameworks
Strengthen the rule of law in smog prevention and control. Relying solely on government departments, factories, enterprises, and resident groups to voluntarily maintain the atmospheric environment is insufficient. Gradually formulate and implement relevant laws and regulations to ensure long-term and stable pollution control.
Comprehensive Pollution Reduction Plans
Develop comprehensive plans to reduce all pollutants and enhance synergistic control measures. It is not enough to focus solely on reducing PM2.5; all pollutant gases and particulates must be addressed, including sulfur compounds and ammonia emissions.
Targeting Primary Gas Emissions
Emissions of carbon monoxide (CO), sulfur dioxide (SO₂), nitrogen oxides (NOₓ), volatile organic compounds (VOCs), and ammonia (NH₃) should be controlled at the source. In the power industry, simultaneously controlling SO₂, NOₓ, VOCs, and dust can help lower pollution control costs.
Joint Control of Multiple Pollutants
While PM10 concentrations have been declining annually, PM2.5 levels remain high. Therefore, regional air pollution control should prioritize the reduction of fine particulates and the joint control of multiple pollutants.
Enhancing Fuel Quality and Emission Standards
To address nitrogen oxide emissions in smog, improve fuel quality and enforce stricter emission standards. The mismatch between fuel quality and standards has become a primary cause of these emissions.
Implementing Stricter Vehicle Regulations
Large cities should actively promote the early implementation of stricter emission standards based on actual conditions. Effectively controlling the number of motor vehicles is essential.
Innovative Solutions for Emission Reduction
For example, modern container gantry cranes at shipping terminals trialing hydrogenated vegetable oil have reduced carbon emissions by 87%.
Industrial Structure Adjustment
Focus regional source control on industrial structure layout and adjustment. The proportion of the tertiary sector should be increased, while the proportion of high-energy-consuming secondary sectors should be reduced.
Industrial Layout Considerations
High-pollution enterprises should be relocated to downwind areas or high-altitude regions. This relocation facilitates the dispersion and deposition of primary pollutants. Strengthen environmental supervision measures and control the addition of new emission sources.
Scientific Approaches to Smog Control
Prioritize scientific approaches in addressing smog issues. Due to the complex sources and unclear formation principles of PM2.5 in China, outdated observation and analysis equipment hinder the development of effective plans.
Avoid blindly adopting foreign monitoring technologies or directly copying foreign control standards. Instead, accelerate basic research, increase scientific investment, and develop a comprehensive PM2.5 reduction and control plan based on scientific research results.
Importance of Public Participation
Public participation is essential in combating smog pollution. Public behavior is a crucial control factor for point source intensity. Improve the overall quality of citizens by considering pollution reduction in daily activities such as dining and commuting, as well as in major decisions like employment and housing.
Targeted Control of Point Source Emissions
Control point source emissions using targeted approaches. Begin with source control by significantly reducing primary gas emissions, focusing on gases such as SO₂, NOₓ, CO, NH₃, and VOCs before PM2.5 formation.
Emission Control Priorities
Prioritize controlling SO₂ emissions in industries, heating, and coal-fired power plants. Emphasize NOₓ control in motor vehicles, coal-fired power plants, and industries. Control CO emissions in motor vehicles, industries, and coal-fired power plants by implementing measures to prevent and reduce pollution.
Innovative Solutions for Energy Savings
Factories can adopt new single girder overhead cranes for energy savings. Using modern design theories can achieve lightweight designs that save energy, materials, and electricity. This technology can save 20,000 tons of coal equivalent annually and reduce carbon dioxide emissions by approximately 50,000 tons each year.
Focus on VOC Emissions
VOCs should primarily focus on motor vehicles, as well as sources like kitchens and dry cleaners, and industries.
Seasonal Emission Control Strategies
In northern cities, winter heating increases emissions of SO₂, NOₓ, CO, and PM compared to non-heating periods. Therefore, strengthen control of these pollutants during the heating season while ensuring VOCs are controlled year-round.
Conclusion
Smog severely impacts the ecological environment of cities. It also poses challenges to public health and socio-economic development. Analyzing the causes, harms, and solutions to smog shows that addressing this issue requires coordinated efforts. Temporary measures can improve air quality in the short term.
However, long-term air purification relies on systematic policy formulation and strict implementation. Governments should strengthen environmental regulations and their enforcement.
Enterprises need to adopt clean energy and green technologies. We need to enhance environmental awareness and participate in protection actions. In the future, continuous technological advancements will help improve societal environmental consciousness.
This progress can gradually alleviate smog, creating a healthier living environment. Let us leave blue skies and white clouds for future generations.
Frequently Asked Questions
What is smog?
Smog is a type of air pollution characterized by a mixture of smoke and fog. It typically consists of harmful particles and gases, including nitrogen oxides and volatile organic compounds, which can originate from vehicle emissions, industrial activities, and other human-made sources. Smog can significantly impair visibility and pose serious health risks to humans and ecosystems.
What causes urban air pollution?
Urban air pollution primarily arises from:
- Traffic Emissions: Vehicles contribute significantly to nitrogen oxides and particulate matter.
- Industrial Activities: Factories release a variety of pollutants, including heavy metals and volatile organic compounds.
- Energy Consumption: Residential and commercial energy use generates substantial air pollutants.
- Agricultural Practices: Farming activities release ammonia and other gases that contribute to air quality degradation.
What measures can be taken to reduce smog?
Effective strategies for reducing smog include:
- Implementing stricter vehicle emissions standards.
- Promoting public transportation and non-motorized transport options.
- Encouraging the use of cleaner energy sources.
- Enforcing regulations on industrial emissions.
- Raising public awareness about pollution sources and health impacts.
