Air Quality Measurement: Understanding The Process And Parameters

Air quality is a measure of the amount and type of pollutants in the air. These pollutants can include particulate matter and gaseous pollutants, such as nitrogen oxides, ozone, sulfur oxides, and carbon monoxide. Poor air quality can have detrimental effects on human health, with 99% of the global population breathing air that exceeds the World Health Organization's guideline limits for air pollution. To measure air quality, organizations like the U.S. Environmental Protection Agency (EPA) and NASA use the Air Quality Index (AQI), which provides a numerical value and category to indicate the level of air pollution in a given region. This value is calculated by measuring the concentration of various pollutants, often using a combination of ground-based instruments and satellite technology.

The Air Quality Index (AQI)

The six categories are:

• Green (0-50) - Good: Air pollution is of little to no risk.
• Yellow (51-100) - Moderate: Air quality is acceptable, but some may be at risk, especially those with heightened sensitivity to air pollution.
• Orange (101-150) - Unhealthy for Sensitive Groups: People with sensitivities may experience negative health effects, but the general public is less likely to be affected.
• Red (151-200) - Unhealthy: The general public may experience health effects, and those with sensitivities may experience more serious effects.
• Purple (201-300) - Very Unhealthy: Health warnings of emergency conditions concerning the entire population.
• Maroon (301-500) - Hazardous: Health alert and emergency conditions for the entire population.

The AQI is calculated using data from air quality monitors, which are outfitted with sensors designed to detect specific pollutants. Some use lasers to scan particulate matter density, while others rely on satellite imaging. The data is then processed by air quality databases, which may weigh the data differently based on reliability and the type of pollution measured.

The AQI is an essential tool for understanding the health effects of air pollution and taking necessary precautions to protect public health.

Ground and satellite monitoring

Satellite monitoring plays a crucial role in filling the gaps left by ground monitoring. Satellites can provide a more comprehensive view of air quality by covering larger areas and detecting pollutants that may be missed by ground monitors. This is especially useful for identifying air pollution hotspots, studying health effects, and tracking long-term air pollution trends. For example, NASA's Moderate Resolution Imaging Spectroradiometer (MODIS) can detect fires and hotspots on the ground, indicating potential sources of air pollution.

One challenge with satellite monitoring is that it may not accurately represent pollution levels on the ground. Satellites measure pollutants in the entire atmosphere, so the pollution observed could be kilometres above the Earth's surface. To address this, ground measurements are necessary to "ground truth" or calibrate satellite-based estimates. By comparing ground measurements with satellite data, we can determine if the pollution observed by satellites is high in the atmosphere or close to the ground where it directly affects the air we breathe.

Both ground and satellite monitoring play important roles in understanding air quality. Ground monitoring provides detailed information about specific locations, while satellite monitoring offers a broader perspective and the ability to detect long-range transport of pollutants. By combining these two methods, scientists can gain a more comprehensive understanding of air quality and its potential impacts on human health and the environment. Additionally, advancements in satellite technology and remote sensing techniques are enhancing our ability to track air pollution concentrations and associated health risks.

Health impacts of poor air quality

Poor air quality has a range of adverse health impacts. Air pollution is a mix of hazardous substances from both human-made and natural sources. These include vehicle emissions, fuel oils, natural gas, manufacturing by-products, power generation, and chemical fumes. When inhaled, these pollutants can enter the bloodstream and contribute to coughing, itchy eyes, and cause or worsen many breathing and lung diseases, leading to hospitalizations.

In the short term, exposure to air pollution can cause wheezing, coughing, and shortness of breath. It can also trigger asthma attacks and acute bronchitis, and increase the risk of respiratory infections. Additionally, short-term exposure to higher levels of outdoor air pollution is associated with reduced lung function, cardiac problems, and abnormal heartbeats.

Over time, breathing in fine particles in the air increases the chances of developing chronic obstructive lung disease (COPD), chronic bronchitis, cardiovascular disease, or lung cancer. It is also linked to a higher risk of developing several neurological disorders, including Parkinson's disease, Alzheimer's disease, and other dementias. Poor air quality is a major cause of premature death and disease, with certain population groups being more vulnerable to its adverse effects.

Children, pregnant women, older adults, and individuals with pre-existing heart and lung diseases are more susceptible to the health impacts of air pollution. People in low-income communities and minority populations are disproportionately exposed to air pollution and are more vulnerable due to factors such as proximity to industrial sources, underlying health issues, poor nutrition, and stress. Additionally, certain agricultural practices, such as burning crop remnants, can negatively impact children's respiratory health.

The health impacts of air pollution vary depending on age, location, underlying health conditions, and socioeconomic factors. It is essential to prioritize emission reduction activities, air monitoring, and other efforts to improve air quality and protect public health, especially for vulnerable populations.

The role of governments and organisations

Governments and organisations play a crucial role in monitoring and improving air quality. Air pollution is a pressing global issue, with the World Health Organization (WHO) reporting that 99% of the global population breathes air that exceeds recommended pollution limits. This has significant health implications, with polluted air contributing to approximately seven million premature deaths annually.

To address this crisis, governments and organisations must strengthen their air quality monitoring and regulation efforts. This involves deploying air quality sensors and monitors that can measure various pollutants, including particulate matter (PM2.5 and PM10), ground-level ozone, nitrogen dioxide, sulfur dioxide, and carbon monoxide. These sensors can be ground-based or satellite-based, with satellites like NOAA's GOES-R Series and the Joint Polar Satellite System (JPSS) providing particle pollution measurements.

In addition to monitoring, governments play a vital role in establishing and enforcing air quality standards and regulations. For example, the United States Environmental Protection Agency (EPA) has developed the Air Quality Index (AQI) as a tool to communicate about outdoor air quality and health. The AQI has six colour-coded categories, ranging from "Good" to "Hazardous," that correspond to different levels of health concern. This helps people quickly assess the air quality in their communities and take necessary precautions.

Organisations like NASA also contribute to air quality monitoring through initiatives such as the Tropospheric Emissions: Monitoring of Pollution (TEMPO) mission, which measures air quality and pollution over North America. NASA's Land, Atmosphere Near-real-time Capability for Earth Observations (LANCE) tool provides air quality forecasters with timely data. Additionally, NASA's Trace Gas Group (TGGR) has developed low-cost air quality sensors to capture data in California, Colorado, and Mongolia.

Furthermore, governments and organisations can collaborate to develop innovative solutions. For instance, the United Nations Environment Programme (UNEP), in partnership with IQAir, created the first real-time air pollution exposure calculator in 2021. This calculator combines global readings from over 6,000 locations worldwide to assess population exposure to air pollution. Such initiatives highlight the importance of collaboration in tackling the complex issue of air quality measurement and improvement.

Addressing air pollution

Air quality is a growing concern for people worldwide. According to the World Health Organization, 99% of the global population breathes unclean air, and air pollution causes 6.7 million premature deaths annually. Poor air quality has detrimental effects on the respiratory health of children and increases the potential for short-term respiratory infections, which can hinder educational opportunities. It can also cause low birth weight, early onset high blood pressure, and an increased risk of autism.

To address the air pollution crisis, governments must take urgent action to strengthen air quality regulation and monitoring capacity. This includes creating policies and passing laws that restrict air pollution, such as the Clean Air Act, which paved the way for numerous efforts to improve air quality in the United States. Most industrialized countries have laws and regulations about air quality, and these regulations are helping to reduce toxic air pollutants and improve health. However, the effects of air pollution are still apparent, and more action is needed to improve air quality and slow climate warming on a national and global scale.

At the individual and community levels, there are several actions that can be taken to reduce air pollution. These include:

• Limiting backyard fires in cities, as smoke from these fires can cause unhealthy conditions, especially for those with asthma or other lung conditions.
• Planting and caring for trees, as trees filter pollutants, absorb carbon dioxide, and release oxygen into the atmosphere.
• Switching to electric or hand-powered lawn equipment, as gas-powered small engines often lack pollution control devices.
• Directing local businesses, city offices, and school districts towards programs that can help them reduce air pollution and become more sustainable, such as the Small Business Environmental Assistance Program in Minnesota.
• Educating residents on best practices for reducing air pollution and providing incentives for beneficial behaviors.

Additionally, policies supporting cleaner transport, energy-efficient homes, improved power generation, better waste management, and access to clean household energy can help reduce outdoor air pollution. Shifting to clean modes of power generation, prioritizing rapid urban transit, and increasing the use of low-emissions vehicles and fuels are also important steps to address air pollution.

Frequently asked questions