Air Quality Index: Pollutants That Affect Our Air

The Air Quality Index (AQI) is a system used to warn the public about dangerous levels of air pollution. The AQI is an indicator of how polluted the air currently is or how polluted it is forecast to become. The AQI tracks six major air pollutants, including ozone (smog) and particle pollution (PM2.5 and PM10), which are known to be harmful to human health. The higher the AQI value, the greater the level of air pollution and the greater the health concern. Therefore, when the AQI is high, people are generally advised to reduce physical activity outdoors or even stay indoors.

Particle pollution

Fine and coarse particles differ in their sources, composition, and health effects. While it is hypothesized that specific components may be responsible for particle pollution-related health issues, the evidence is not sufficient to differentiate these sources. Overall, the evidence indicates that many particle pollution components are linked to increased mortality, cardiovascular disease, respiratory disease, and lung cancer. Both short-term acute exposure to high levels and long-term chronic exposure to low levels of particle pollution can be harmful. Fine particles can penetrate deeply into the respiratory tract, reaching the lungs and causing irritation, coughing, sneezing, and shortness of breath. They can also worsen existing medical conditions and increase the risk of heart attacks.

Ozone

Tropospheric ozone is not directly emitted into the atmosphere but is formed by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOCs). These chemical reactions occur when pollutants from cars, power plants, industrial boilers, refineries, and chemical plants react in the presence of sunlight. Ground-level ozone is particularly dangerous on hot, sunny days in urban areas, but it can also reach high levels during colder months. Furthermore, wind can carry ozone over long distances, leading to elevated levels even in rural regions.

The health impacts of ozone pollution are significant. Even short-term exposure can cause greater obstruction of airways, as seen in a study of lifeguards working in Galveston. Certain groups are especially vulnerable to the effects of ozone, including individuals with pre-existing medical conditions such as lung diseases (e.g., asthma), metabolic disorders, and nervous system issues. Research also suggests that women may be at a higher respiratory health risk. Long-term exposure to ozone pollution has been linked to increased respiratory illnesses, metabolic disorders, reproductive issues, and increased mortality related to respiratory and cardiovascular problems.

It is important for individuals to be aware of ozone levels and take necessary precautions to protect their health. Staying informed about air quality forecasts and taking steps to reduce air pollution can help mitigate the harmful effects of ozone on human health and the environment.

Nitrogen dioxide

The Air Quality Index (AQI) is a system used to warn the public about dangerous levels of air pollution. The AQI runs from 0 to 500, with higher values indicating greater levels of air pollution and health risks. An AQI value of 50 or below represents good air quality, while a value over 300 indicates hazardous air quality. The AQI tracks six major air pollutants, including nitrogen dioxide (NO2), a gaseous pollutant composed of nitrogen and oxygen.

NO2 is a significant contributor to particle pollution and the chemical reactions that produce ozone (O3). It is often found in higher concentrations in large urban regions and near heavily travelled roadways. The highest levels of NO2 are typically observed during rush hours in cities. Additionally, NO2 can form indoors when fuels like wood or gas are burned.

To address the issue of NO2 pollution, the EPA establishes an AQI for nitrogen dioxide and provides year-round forecasts, including maps that show how pollution levels change. This information helps individuals take necessary precautions to protect themselves and their families from unhealthy levels of air pollution, especially those who are more vulnerable to its effects, such as children, the elderly, and people with pre-existing medical conditions.

Sulfur dioxide

The Air Quality Index (AQI) is a system used to warn the public when air pollution is dangerous. The AQI tracks six categories of air pollution, including ozone (smog) and particle pollution (from smoke, power plants, factories, vehicle exhaust, etc.). The AQI value runs from 0 to 500, with higher values indicating greater levels of air pollution and health concerns. An AQI value of 50 or below represents good air quality, while an AQI value of over 300 represents hazardous air quality.

SO2 is a harmful pollutant that can have significant health and environmental impacts. When emitted into the air, SO2 can react with other compounds to form small particles that contribute to particulate matter (PM) pollution. These particles can penetrate deeply into the lungs and, in sufficient quantities, can cause health problems, particularly for individuals with respiratory conditions or compromised immune systems. Additionally, high concentrations of SO2 and other sulfur oxides can contribute to acid rain, which can harm sensitive ecosystems, damage foliage, and decrease plant growth.

To address the negative effects of SO2 pollution, the United States Environmental Protection Agency (EPA) has established national ambient air quality standards for SO2. These standards aim to protect against exposure to sulfur oxides (SOx) and reduce people's exposure to harmful gases. EPA's rules to reduce SO2 emissions help state and local governments meet the Agency's national air quality standards. Control measures that decrease SO2 emissions can also reduce the formation of particulate sulfur pollutants and other harmful compounds.

By monitoring SO2 levels through the AQI and implementing measures to reduce emissions, communities can protect public health and mitigate the environmental impacts associated with this harmful air pollutant. It is important for individuals to stay informed about their local AQI levels and take necessary precautions to safeguard their health during periods of high air pollution.

PM2.5 and PM10

The Air Quality Index (AQI) is a system used to warn the public when air pollution is dangerous. The AQI runs from 0 to 500, with higher values indicating greater levels of air pollution and health risks. An AQI value of 50 or below represents good air quality, while a value of over 300 indicates hazardous air quality. The AQI tracks six major air pollutants, including ozone (smog) and particle pollution.

PM10 refers to inhalable particles with diameters of 10 micrometres or less. These particles can be inhaled into the lungs and can induce adverse health effects, especially in the upper region of the lung. Sources of PM10 include dust from construction sites, landfills, agriculture, wildfires, industrial activities, wind-blown dust, pollen, and bacterial fragments.

PM2.5 refers to fine inhalable particles with diameters of 2.5 micrometres or less. These particles are small enough to travel into the deeper parts of the lung and can cause serious health issues. PM2.5 is often a result of emissions from the combustion of gasoline, oil, diesel fuel, or wood, as well as industrial processes and vehicle exhaust.

Both PM2.5 and PM10 have been associated with adverse health effects, particularly in infants, children, and older adults with pre-existing heart or lung diseases. Short-term exposure to PM2.5 has been linked to increased hospital admissions for heart and lung issues, while long-term exposure has been associated with premature death and reduced lung function growth in children. Exposure to PM10 has been linked to the worsening of respiratory diseases, including asthma and chronic obstructive pulmonary disease (COPD).

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