Life,  Tech

Air Pollution is a Global Problem with Serious Consequences

  Air quality has always been the focus of everyone’s attention. The World Health Organization (WHO) 2021 edition of the “Global Air Quality Guidelines” (the latest version) recommends that the PM2.5 safety standard is an annual (long-term exposure) average concentration of 5 micrograms per cubic meter, and a 24-hour (short-term exposure) average concentration of 15 micrograms per cubic meter.
  Recently, scientists from Monash University in Australia published the results of a study showing that in today’s world, almost no piece of land and space is “pure land”. A study of fine particulate matter (mainly PM2.5) in the daily environment conducted by researchers shows that only 0.18% of the world’s land area and 0.001% of the population live under the PM2.5 safety standard recommended by WHO .
  The research team used traditional air quality monitoring systems, satellite-based weather and air pollution detectors, statistical and machine learning methods to accurately assess the concentration of PM2.5 in various regions of the world. The number of days with higher quality increased, but the number of days with lower air quality increased in South Asia, Australia and New Zealand, and South America and the Caribbean, with the “overwhelming majority” of the world’s areas of non-attainment air quality.
  As of 2019, although the global PM2.5 concentration has decreased slightly, if calculated in daily concentration, more than 70% of the days in the world still have a PM2.5 concentration above 15 micrograms per cubic meter, and in South and East Asia, PM2. .5 More than 90% of days with concentrations above 15 micrograms per cubic meter. Globally, from 2000 to 2019, the average annual concentration of PM2.5 was 32.8 micrograms per cubic meter, much higher than the 5 micrograms per cubic meter recommended by the WHO.
  The regions with the highest annual average concentration of PM2.5 are East Asia, South Asia and North Africa. In addition, the PM2.5 concentrations were higher in winter (December, January, and February) in Northeast China and northern India, and summer (June-August) in eastern North America.
  WHO believes that reducing people’s exposure to particulate matter is a top priority, because PM2.5 and PM10 can penetrate deep into the lungs and even enter the blood. The assessment of WHO is that air pollution can cause comprehensive damage to people. In addition to common lung and cardiovascular diseases (such as lung cancer, high blood pressure, heart disease and stroke, etc.), air pollution can also affect all human organs, causing Diabetes, dementia, mental decline, neonatal diseases and other problems. Globally, more than 7 million people die prematurely every year due to air pollution. As early as 2013, WHO classified PM2.5 as a carcinogen. For maintaining health and preventing diseases, there is no so-called health threshold for pollutants, and all pollutants are harmful to the human body.
  Even with the standard of 2005 (the annual average concentration of PM2.5 is 10 micrograms per cubic meter), more than 90% of the world’s population lives in air that does not meet the standard. Premature deaths from air pollution are concentrated in low- and middle-income countries.
  Having a relatively clean earth is not only beneficial to human health, but also to the survival of other living things. Cleaner air also increases crop yields to meet the food needs of people and livestock. Nitrogen oxides are an important component of air pollution, and a recent study showed that limiting emissions of nitrogen oxides such as nitrogen dioxide can improve crop yields. Cutting nitrogen dioxide emissions to 5 percent of current levels could boost crop yields in China by 28 percent.
  Nitrogen oxides are plant toxins that directly damage plant cells, and they are also a key element in the formation of other pollutants, such as ozone, that can also cause damage to plants. Previous studies have found that the “greenness of crops” observed by satellites is closely related to crop growth and yield. Therefore, the researchers analyzed satellite images of crops in the United States, China, India, Western Europe, and South America from 2018 to 2020, and analyzed these The greenness of satellite imagery of crops in 5 countries and regions is rated. This rating was then compared to nitrogen dioxide levels in satellite data for each region. Using computer simulations, the team estimated what would happen to crop yields in each region if nitrogen dioxide emissions were reduced to 5 percent of current levels. Some estimates show a 28% increase in winter crop production in China and a 17% increase in summer crop production; Western Europe’s winter and summer crop production increased by nearly 10% each; India’s winter crop production increased by 6% and summer crop production increased by 8%.
  If the water is clear, there will be no fish. Some people have different opinions on the latest version of the “Global Air Quality Guidelines” and think that the standards are too strict. Air quality standards, such as PM2.5 concentration, can be discussed.
  So on February 1 this year, the World Meteorological Organization (WMO) said governments and the international scientific community were seriously considering a UN-led plan to tackle climate change by fundamentally improving how atmospheric pollutants are measured around the globe. . At present, there is no comprehensive and timely international exchange process for surface and space-based greenhouse gas observation data.
  WMO must first conduct more scientific and accurate measurements of global air pollution to confirm the extent of global air pollution. This task is mainly accomplished through a network of ground measuring stations initiated by WMO, which is expected to be realized within the next 5 years. Scientists will then be able to verify the accuracy of air quality data flagged by satellites or aircraft.
  WMO also pointed out that humans should bear the main responsibility for global air pollution. In the past, it has been thought that the large-scale atmospheric circulation in the Middle East combined with desert dust and atmospheric dust contributes to air pollution. A recent study found that more than 90% of the fine particulate matter in the air pollutants in the Middle East may come from human activities, further confirming the conclusion of WMO. The study challenges previous consensus in the air pollution research community that natural gas sols, such as desert dust, are the primary cause of poor air quality in the region.
  For the study, the researchers analyzed observational data collected by a research ship that sailed around the Arabian Peninsula in 2017 and combined it with atmospheric modeling. Researchers estimate that more than 90 percent of harmful fine particulate matter in the Middle East comes from human activities, such as the burning of fossil fuels and the oil industry. The concentration of particulate matter in the Middle East has been higher than the WHO standard, and the excess mortality caused by pollution exposure in the northwestern region of the Middle East is 5.9%, and the indicator is 15.9% in the southeastern region of the Middle East; Germany, the two countries with better air quality, had this indicator at 3.0% and 3.7% respectively. The health of citizens in many countries in the Middle East has been seriously affected by air pollution.
  The WHO admits that currently very few countries or regions in the world can limit the concentration of PM2.5 to an annual average concentration of 5 micrograms per cubic meter. However, WHO proposes that as long as more electric vehicles are put on the road, air pollution and greenhouse gas emissions will be reduced. Several related studies have also reached similar conclusions, and the main way to reduce the level of nitrogen oxide pollution is to change the global energy and transportation system. To make the earth’s air cleaner and make all the earth’s inhabitants healthier requires the joint efforts of all human beings.

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