2.5 micron particles have the most health impact for increased cancer and cardiovascular impacts. They are strongly correlated to increased air pollution deaths and hospitalizations.
Due to the arrival of pollutants from north, the PM2.5 density soared to 300 micrograms by 7am from the 120 micrograms recorded at 4am, and the figure continued to rise throughout the afternoon.
The World Health Organization’s safety guideline is 25 micrograms. Shanghai was over 15 times worse than the WHO limit for PM2.5 particles.
As for the larger PM10, its concentration kept growing overnight and hit about 500 micrograms at 4pm, triple the nation’s 150 microgram limit and 10 times the density considered safe by WHO of 50 micrograms.
The city’s average air quality index over 24 hours reached its peak at 6pm with a reading of 287, indicating heavy pollution, while Qingpu District recorded an AQI of 339, or severely polluted.
The Shanghai Meteorological Bureau issued a yellow haze alert at 7:41am for the lingering smog obscuring the city’s skyline. The haze cut visibility in most districts to just 3 kilometers.
During the “London Smog” incident in 1952, levels of PM reached concentrations of 4500 µg/m3. These levels of PM were linked with human disease and death. Shanghai reached 9% of the level of the London fog. The London fog had thousand keeling over and suffocating.
"Particulate matter," also known as particle pollution or PM, is a complex mixture of extremely small particles and liquid droplets. Particle pollution is made up of a number of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles.
The size of particles is directly linked to their potential for causing health problems. EPA is concerned about particles that are 10 micrometers in diameter or smaller because those are the particles that generally pass through the throat and nose and enter the lungs. Once inhaled, these particles can affect the heart and lungs and cause serious health effects. EPA groups particle pollution into two categories:
"Inhalable coarse particles," such as those found near roadways and dusty industries, are larger than 2.5 micrometers and smaller than 10 micrometers in diameter.
"Fine particles," such as those found in smoke and haze, are 2.5 micrometers in diameter and smaller. These particles can be directly emitted from sources such as forest fires, or they can form when gases emitted from power plants, industries and automobiles react in the air.
Particle pollution - especially fine particles - contains microscopic solids or liquid droplets that are so small that they can get deep into the lungs and cause serious health problems. Numerous scientific studies have linked particle pollution exposure to a variety of problems, including:
premature death in people with heart or lung disease,
nonfatal heart attacks,
decreased lung function, and
increased respiratory symptoms, such as irritation of the airways, coughing or difficulty breathing.
People with heart or lung diseases, children and older adults are the most likely to be affected by particle pollution exposure. However, even if you are healthy, you may experience temporary symptoms from exposure to elevated levels of particle pollution.
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