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How did ozone become a deadly enemy? Understand the reasons behind U.S. air standards!
Ozone, once considered a natural barrier to protect us, has gradually become a deadly enemy in the air. The air quality standards in the United States are promulgated by the Environmental Protection Agency to protect public health and environmental safety. Behind these standards, how many unknown stories and efforts are there? This article will provide you with an in-depth understanding of the background and effects of ozone and other major pollutants.
Introduction to the U.S. National Ambient Air Quality Standards (NAAQS)
The U.S. Environmental Protection Agency (EPA) formulated the National Ambient Air Quality Standards (NAAQS) in accordance with the Clean Air Act to limit the concentration of six pollutants in the air, including ozone (O3), particulate matter ( PM2.5 and PM10), lead (Pb), carbon monoxide (CO), sulfur oxides (SOx) and nitrogen oxides (NOx). These pollutants mainly come from activities such as industry, transportation and energy production, causing serious impacts on the environment and health.
Background and Development
Under the Clean Air Act, the EPA must regularly review standards for these pollutants to ensure they reflect the latest scientific research. The effects of ozone were first discovered in the 1950s, when its harmful effects on crops were known. Over time, EPA's standards are revised as new evidence accumulates.
The impact of ozone on health cannot be underestimated, especially for sensitive groups such as children and the elderly.
The two-sided nature of ozone
Ozone helps absorb the sun's ultraviolet rays when it is high in the sky, but once it is at the ground level, it becomes a harmful pollutant. Ground-level ozone is formed from the reaction of nitrogen oxides (NOx) and volatile organic compounds (VOCs). The main sources of these compounds include activities such as emitting vehicles, factories and coal-fired power plants.
The impact of particulate matter (PM2.5 and PM10)
Particles in the air are divided into PM2.5 and PM10 according to their size, both of which pose a threat to health. PM2.5 is extremely small and can penetrate deep into the lungs and even enter the blood circulation system, causing cardiovascular diseases and respiratory problems. Since 1996, the EPA has continuously updated its particulate matter standards to reflect new research and health effects.
The dangers of lead
Since lead was listed as a standard pollutant in the 1970s, the understanding of its impact has continued to update. Major sources of lead exposure are not limited to the air, but also include water and soil, prompting the EPA to focus on reducing overall exposure to lead in the environment.
Carbon monoxide (CO) and sulfur oxides (SOx)
Carbon monoxide is mainly caused by vehicle emissions. The EPA first established its standards in 1971 and maintained the existing standards in 2011. Sulfur oxides are closely related to the burning of fossil fuels, and the EPA continues to review these standards in order to more effectively protect public health.
Monitoring and adjustment of nitrogen oxides (NOx)
NOx is a major factor in the formation of surface ozone. The EPA re-evaluated the NOx standards in 2010 and proposed strengthened monitoring requirements. This series of adjustments is aimed at reducing the impact of industrial and transportation emissions on air quality.
These standards are not only to protect health, but also to protect our environment, crops and ecosystems.
Conclusion
The United States’ air quality standard NAAQS is a comprehensive policy measure designed to protect public health and environmental safety. However, with the advancement of technology and in-depth research, these standards still need to be continuously reviewed and revised. Ozone has transformed from a natural barrier that protects us into a deadly enemy, reflecting the impact of human activities on the environment and associated health risks. Faced with the ever-changing air quality challenges, can all sectors of society work together to find a way out and continue to improve air quality to protect future health?
