What Is the Air Quality Index?

Smoggy air and smoky skies can have a serious impact on your health. In fact, nearly 120 million Americans live in places with unhealthy levels of ozone and particle pollution, two of the most common air pollutants in the country. Not to mention, the last couple of summers have made it clear that the increase in wildfire activity, driven in part by climate change, is having a growing impact on what we breathe in. One way to protect yourself is to refer to the Air Quality Index (AQI). Here’s what to know about it, and what actions you can take when things look bad.

The AQI is a scale that provides real-time information on the amount of pollution in the air. The U.S. Environmental Protection Agency (EPA) developed the index as a way of reporting air quality issues directly to the public.

You can access the AQI on AirNow, a collaborative program of several government agencies, including the EPA, the National Weather Service, and Centers for Disease Control and Prevention, among other partners. There’s also an app you can download. (Note: People can use other sources outside of AirNow to check local air quality. PurpleAir is one; the crowd-sourced platform gets its data from a global network of 8,000 environmental sensors, many of them mounted on private homes.)

The scale is split into six categories, each with a color and a number corresponding to the amount of pollution in the air and its potential impact on public health. An AQI number above 100 means that a pollutant has gone beyond the national standard for that pollutant, set by the EPA. The higher the number, the greater the health risk.

If the AQI value exceeds 100, state and local agencies will put out an air quality alert to warn those who are most sensitive to pollution impacts. If the value is above 300, alerts will notify everyone in the affected area to be careful in these conditions. (In the United States, there have been about 40 instances in the last decade when the AQI reading went above 500, mostly in the West due to wildfire smoke.)

• Carbon monoxide: An odorless, colorless gas that is released when something is burned, like gas from a stove. Other sources include wildfires and industrial facilities.
• Nitrogen dioxide: A reddish-brown, highly reactive gas coming primarily from the burning of fossil fuels, especially from vehicles and power plants.
• Ozone: A major part of the gnarly mix we call smog. This gas forms when two types of pollutants (nitrogen oxides and volatile organic compounds) react in the presence of sunlight.

• Particle pollution: Tiny airborne particles—PM2.5 and PM10—that are both emitted directly and formed in the atmosphere. Key sources include soot from cars, trucks, and power plants; dust from construction sites; and smoke from wildfires.
• Sulfur dioxide: A colorless gas that is emitted from the burning of fossil fuels in power plants and other industrial facilities.

The concentration of each of the five pollutants is measured hourly and/or daily—depending on the pollutant—via air monitors set up in about one-third of all counties in the country. An AQI value is calculated for each pollutant and whichever one has the highest value becomes the overall AQI for that period of time. For example, if the AQI value were 100 for ozone and 80 for particle pollution at noon in Manhattan, the number you’d see on AirNow for Manhattan would read as 100. Monitoring stations also use the data to forecast upcoming pollution levels and to provide AQI warnings regarding possible poor air quality the next day.

For some communities, the AQI value may not reflect true conditions, particularly when monitors are not located near the places where pollution is most potent, such as in a city’s industrial corridors. This is especially worrying for low-income communities and people of color, who are more likely to live near highways and polluting facilities. An inaccurate AQI reading would further put these populations at risk.

Another issue is with the national standards for the pollutants themselves, notes Emily Davis, a senior attorney for NRDC’s Climate & Clean Energy Program who worked on the 2021 lawsuit that challenged the EPA over air pollution standards for ozone. Davis has called the EPA’s underlying guidance on ozone pollution out-of-date as well as out of sync with what health science considers harmful. The EPA’s outside scientific advisors have recommended strengthening national standards for ozone from 70 parts per billion (ppb), the current standard set in 2015, to between 55–60 ppb. But in August, the EPA announced that it will not continue its reconsideration of Trump-era ozone standards and will instead start over, with a full review to be completed by the end of 2025.

For fine particulate matter (PM2.5), the EPA’s current national standards are set at an annual average level of 12 micrograms per cubic meter (mcg/m3) and a daily level of 35 mcg/m3. In January 2023, the EPA proposed changing the annual standard to 9 or 10 mcg/m3 but didn’t plan for any changes to the daily level. While the proposal would be an improvement on the decade-old standards being used right now, it’s still well above the level that the World Health Organization recommends in its recently revised air quality guidelines: 5 mcg/m3. Updated EPA standards are expected in late fall.

So while it is still very important to check the AQI, keep in mind that the system isn’t perfect. Bottom line:

SDGs, Targets, and Indicators Analysis

1. Which SDGs are addressed or connected to the issues highlighted in the article?

The following SDGs are addressed or connected to the issues highlighted in the article:

• SDG 3: Good Health and Well-being
• SDG 11: Sustainable Cities and Communities
• SDG 13: Climate Action

2. What specific targets under those SDGs can be identified based on the article’s content?

The specific targets under the identified SDGs are:

• SDG 3.9: By 2030, substantially reduce the number of deaths and illnesses from hazardous chemicals and air, water, and soil pollution and contamination.
• SDG 11.6: By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management.
• SDG 13.1: Strengthen resilience and adaptive capacity to climate-related hazards and natural disasters in all countries.

3. Are there any indicators mentioned or implied in the article that can be used to measure progress towards the identified targets?

The article mentions or implies the following indicators that can be used to measure progress towards the identified targets:

• Air Quality Index (AQI): The AQI is a scale that provides real-time information on the amount of pollution in the air.
• Concentration of major air pollutants: The article mentions carbon monoxide, nitrogen dioxide, ozone, particle pollution (PM2.5 and PM10), and sulfur dioxide as major air pollutants that are measured and regulated.
• National standards for air pollutants: The article discusses the current national standards for pollutants such as ozone and fine particulate matter (PM2.5) and the proposed changes to these standards.

Table: SDGs, Targets, and Indicators

Behold! This splendid article springs forth from the wellspring of knowledge, shaped by a wondrous proprietary AI technology that delved into a vast ocean of data, illuminating the path towards the Sustainable Development Goals. Remember that all rights are reserved by SDG Investors LLC, empowering us to champion progress together.

Source: nrdc.org

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