HOW IS AIR QUALITY MEASURED?

Air quality is an important part of the health of the world, and there are many ways to measure it. Pollutant levels are measured by air quality sites in each country or region. Each country or region then sets up an air quality index and sorts the raw data into categories to make a detailed rating scale.

The Air Quality Index (AQI) is a popular way to measure air quality. It works like a thermometer that goes from 0 to 500 degrees. AQI takes numbers and turns them into a scale that describes the amount of pollution in the air.

This makes it easier for people of all ages to understand how dirty the air they breathe is. Based on pollution and health concerns, different countries and areas use different scales to report on the quality of the air. All over the world, dozens of local indexes are used.

There has been a lot of talk about air quality in recent years. Several parts of the northeastern United States experienced some of the worst air quality in almost 15 years last July.

Here are seven things about measuring air quality that you should know.

How is Air Quality Measured?

The Air Quality Index measures air quality

The air quality index also called a AQI, as we know it today, was made public in 1999. It has changed over the years, but the goal has always been the same: to give people a daily report that is easy to understand about the air they breathe.

AirNow.gov says that the AQI runs from 0 to 500 and has six colour-coded categories representing a different amount of health risk. Basically, a smaller number means that the air quality is better, and a bigger number means that the air quality is worse.

There are six major toxins in the air

Managers of air quality monitoring system keep an eye on particle pollution, ozone, carbon monoxide, sulphur dioxide, nitrogen dioxide, and lead. Of these, particle pollution and ozone make up the majority of air polluters.

There are many air quality monitoring systems which use with AQI to measure air quality, Likewise, AirNow.gov says that the reporting time for each pollution in the AQI is different. For example, the AQI for ozone is good for eight hours, but the AQI for particle pollution is good for 24 hours.

Lead is not mentioned in daily updates on air quality

Even though the Environmental Protection Agency checks for lead, it is not included in the daily AQI data. A representative for the EPA said that’s because the effects of lead pollution build up over time.

“The AQI focuses on health effects that could happen within a few hours or days,” the representative said in a written statement. “Health effects from airborne lead tend to build up over longer periods of time. Because of this, it is not possible to report daily on air quality and possible health effects from lead exposure.”

If the air quality is bad, there might be an air quality action day

An air quality action day, also called an air quality alert day, is declared when the AQI hits levels that are dangerous.

In the United States, there are many agencies that try to keep the air clean. Each of these agencies has its own way of talking about bad air days and uses a different AQI number to measure them.

WHAT IS AN AIR QUALITY ACTION DAY?

AirNow.gov says that most air quality action days happen when the AQI is predicted to be dangerous, or Code Red (AQI value of 151 to 200). In this case, everyone should limit their exposure to air pollution, especially people who are more likely to be hurt by the pollutant of the day.

At this link, AirNow.gov tells you several things you can do every day to help keep the air better.

Air quality data are collected by instruments on the ground and in space

The EPA says that air pollution levels are measured at more than 4,000 tracking stations, most of which are owned and run by state environmental agencies. These groups send the EPA’s Air Quality System database their hourly or daily measurements of how much pollution is in the air.

Also, satellites in orbit around the Earth gather information about the state of the air. For example, NOAA says that its GOES-R Series satellites keep an eye on particle pollution in the air.

The Joint Polar Satellite System (JPSS) also gathers information about the particles in our air. NOAA said these include smoke from wildfires, dust in the air during dust and sand storms, pollution from cities and factories, and ash from volcanoes that erupt. The JPSS satellites can also measure the amount of ozone near the ground.

The seasons change the quality of the air

When summer temperatures rise, the air quality in big towns generally gets worse, especially when it comes to ozone levels.

In the upper regions of the atmosphere, ozone is good because it saves us from the sun’s harmful ultraviolet rays.

The PSCAA says that ozone is at its worst on hot summer days when the hot sun ‘cooks’ daily emissions from cars, factories, paints, cleaners and petrol fumes.

But in some colder places, the air is still dirty in the winter. In these places, it’s not ozone that makes the air bad, but tiny particles, like wood smoke from a campfire. UCAR said that leaving cars running to cool or keep them warm also adds to the amount of pollution in the air.

“We can get very strong inversions in mountainous areas,” said Joost de Gouw, a chemistry professor at the University of Colorado Boulder and a fellow at the Cooperative Institute for Research in Environmental Sciences.

An inversion is a good way to keep pollutants close to the ground. “Therefore, in many places, like Salt Lake City, the air quality is the worst in the winter because the airspace is closed off.”

An inversion happens when the temperature rises with height, putting warmer air above colder air. Since cold air is more thick than warm air, it stays close to the top of the Earth.

Some places will ban fires because they are bad for the air quality when strong inversions happen in the winter.

The sources of pollution in the air have changed over time

Most people think that cars and factories are the main sources of air pollution, and this is true. Because there are more tiny particles in the air, wood smoke from wildfires or home stoves can also make the air quality worse.

Scientists say that because of stricter rules, the sources of air pollution have changed over time.

WHERE DO THE MOST POLLUTANTS IN THE AIR COME FROM?

“Twenty years ago, I would say that transportation and motor vehicles, power generation, and industry were the top three sources of air pollution,” de Gouw said.

But the Clean Air Act, which was passed in 1970 and changed in 1977 and 1990, has made these forms of pollution less harmful.