Air Quality Index: Understanding The Good Range

The Air Quality Index (AQI) is a system that warns the public about dangerous levels of air pollution. It is a yardstick that 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 a value over 300 indicates hazardous air quality. The AQI tracks six categories of air pollution, including ozone (smog) and particle pollution from sources like smoke, power plants, and vehicle exhaust. It is important to stay informed about the AQI in your area to take necessary precautions, especially for individuals with asthma, lung diseases, diabetes, or cardiovascular disease.

AQI as a yardstick

The Air Quality Index (AQI) is a yardstick that measures air pollution levels on a scale of 0 to 500. An AQI value of 50 or below represents good air quality, with little to no potential risk to public health. Values over 300 indicate hazardous air quality, posing an immediate danger to the public. The AQI is an essential tool for the public and health officials to monitor and address air pollution levels and their potential health impacts.

The AQI is calculated based on the concentration of several key air pollutants, including ground-level ozone and particle pollution from sources such as smoke, power plants, vehicles, and wildfires. These pollutants are known to have significant health impacts, especially for individuals with respiratory conditions, the elderly, children, and those with pre-existing health conditions. By providing a numerical value and associated health risks, the AQI offers a clear and accessible way to communicate air quality information to the public.

The AQI is typically divided into six categories, each assigned a specific colour and health advisory. These categories range from "Good" or "Satisfactory" at the lower end of the scale to "Hazardous" or "Emergency" at the upper end. For example, an AQI value of 100 is generally considered the threshold between satisfactory and unhealthy air quality. Values above 100 indicate an increased risk to public health, with the potential for adverse effects on vulnerable individuals.

The specific health advisories associated with each AQI category provide important guidance to the public. For instance, on days with an AQI value in the "Unhealthy" range, individuals are advised to reduce outdoor activities, especially in high-traffic areas, and to take precautions to minimise their exposure to air pollution. Similarly, during "Hazardous" or "Emergency" conditions, everyone is advised to stay indoors as much as possible to limit their pollution intake.

The AQI is an invaluable tool for individuals, communities, and policymakers to assess and address air quality concerns. By providing a standardised metric, the AQI enables comparisons between different locations and over time. This information can inform policies and interventions to improve air quality and protect public health. Additionally, the AQI helps raise awareness about the impacts of air pollution, empowering individuals to take proactive measures to safeguard their health and well-being.

How AQI is calculated

The Air Quality Index (AQI) is a tool developed by the EPA to communicate information about outdoor air quality and health. The AQI is calculated by converting measured pollutant concentrations to a uniform index based on the health effects associated with a pollutant. The health benchmarks used for calculating the AQI are pollutant-specific and are established by the EPA through the National Ambient Air Quality Standards. The Clean Air Act requires the EPA to review these standards every five years.

The AQI is based on the concentrations of five pollutants: ozone, nitrogen dioxide, sulfur dioxide, PM2.5, and PM10. The breakpoints between index values are defined for each pollutant separately, and the overall index is defined as the maximum value of the index. The AQI is divided into six categories, each corresponding to a range of index values and a different level of health concern. The six categories are: Good, Moderate, Unhealthy for Sensitive Groups (USG), Unhealthy, Very Unhealthy, and Hazardous. An AQI value of 50 or below represents good air quality, while an AQI value over 300 represents hazardous air quality.

The final AQI value can be calculated either per hour or per 24 hours and is the maximum of these six scores. The score for each pollutant is non-linear, as is the final AQI score. The AQI was developed to provide a simple, uniform way to report daily air quality conditions. The pollutant with the highest AQI value determines the overall AQI for that hour.

AQI forecasts heavily depend on temperatures, precipitation, wind, and cloud cover. Weather affects pollution creation and transport from other areas. AQI forecasts enhance human health by helping residents avoid risks from air pollution.

How to protect your health

Air pollution can be extremely harmful to health, and it is important to take steps to protect yourself and your family. The Air Quality Index (AQI) is a valuable tool to help you make informed decisions about your activities and keep yourself safe. AQI values at or below 50 are considered good air quality and are safe for everyone to spend time outdoors without posing a risk to health. Values over 300 are considered hazardous.

• Limit outdoor time – The more time spent outdoors, the more pollution is inhaled, so limit your time outdoors to 30 minutes or less. If you must go outside, consider wearing a well-fitted N95 mask, which provides better protection than cloth or surgical masks.
• Keep windows closed – Keep your windows closed and set your air conditioning or heating system to re-circulate air instead of drawing it from the outside.
• Avoid high-traffic areas – Stay away from high-traffic areas, and do not exercise near those locations.
• Switch to indoor activities – Move your fitness activities indoors, such as running on a treadmill or walking in a mall.
• Avoid cooking – Cooking, especially frying or grilling, can increase indoor air pollution.
• Use an air filter – An air filter can help improve the air quality in your home by capturing pollutants and circulating clean air.
• Be cautious with children – Encourage children to play inside, and follow local recommendations and guidelines for children's outdoor activities.
• Be mindful of high-risk groups – High-risk groups, including children, adults over 65, pregnant women, and people with chronic heart or lung disease, should take extra precautions and follow their doctor's recommendations.

By following these steps, you can help protect your health and the health of your loved ones during periods of poor air quality.

Real-time air pollution data

The Air Quality Index (AQI) is a system used to warn the public when air pollution is dangerous. The AQI is a yardstick that runs from 0 to 500. The higher the AQI value, the greater the level of air pollution and the greater the health concern. For example, an AQI value of 50 or below represents good air quality, while a value over 300 indicates hazardous air quality. The AQI breaks air pollution levels into six categories, each of which has a name, an associated colour, and advice. Values at or below 100 are considered satisfactory for almost everyone, while values above 100 indicate unhealthy air quality.

Another source of real-time air pollution data is the AirNow Interactive Map, which includes data for the US, Canada, and Mexico. The map shows the current air quality for ozone or particulate matter (PM), whichever is highest. It also provides forecasts for the next 24 hours, which are available from 4 pm local time. The AirNow website also offers a mobile app and email alerts to help users stay informed about air quality.

The GAIA air quality monitor is another tool that provides real-time air pollution data. It uses laser particle sensors to measure PM2.5 and PM10 particle pollution, which is one of the most harmful types of air pollution. The monitor is easy to set up and requires only a WiFi access point and a USB-compatible power supply.

These sources of real-time air pollution data can help individuals protect their health by allowing them to adjust their plans and avoid long periods of outdoor activity when air quality is poor.

AQI and health advisories

The Air Quality Index (AQI) is a system used to warn the public about dangerous levels of air pollution. It is a nationally uniform, colour-coded index that reports on and forecasts daily air quality. The AQI is calculated on a scale from 0 to 500, with 0 indicating perfect air quality and 500 indicating extremely hazardous air quality that poses an immediate danger to the public. The higher the AQI value, the greater the level of pollution and the more serious the health concern.

Each AQI category is colour-coded to make it easy for people to quickly determine whether the air quality is safe. Values at or below 100 are generally considered safe for everyone. Values over 100 indicate that air quality is unhealthy and that the higher the number, the more people are at risk of health issues. An AQI value of over 300 is hazardous to everyone and people are advised to stay indoors as much as possible.

Health advisories are issued when air quality is forecast to be unhealthy. These advisories are most effective when they are widely available and easy to understand. Newspapers, radio, television, and websites report AQI levels and health advisories year-round. Evidence shows that air quality alerts are helpful, and that advice from healthcare professionals can be particularly powerful in encouraging people to change their behaviour. For example, during an "Action Day", mandatory restrictions may be put in place to limit indoor burning to certain devices, and people may be advised to reduce their driving and to avoid rigorous outdoor activity.

Specific health advisories are issued for sensitive groups, such as children, the elderly, people with asthma or other lung diseases, people with diabetes or cardiovascular disease, and pregnant women. These groups are advised to take extra precautions when air quality is poor, such as staying indoors, avoiding high-traffic areas, and reducing physical activity. Even healthy adults who exercise or work outdoors can be harmed by poor air quality, so it is important for everyone to be aware of the AQI and to take steps to protect their health when necessary.

Frequently asked questions