[News] Smoke cloud over North America: how the air quality index is measured and how it impacts health if it is considered unhealthy

[#Steeven.™]

Millions of people on the east coast of North America have had to wear masks due to the huge cloud of smoke moving through the region, caused by a chain of forest fires in Canada.

Data from the US Environmental Protection Agency's (EPA) Air Quality Index (AQI) shows that some cities across the country had the worst air quality in the world on Thursday morning .

Cities like Washington DC, Philadelphia, and New York had significantly worse air quality than highly polluted places like Lahore, Dhaka, and Hanoi.

Some areas of Canada also have excessive levels of air pollution. This was the case for Janvier, in Alberta, which registered an AQI of 338, above Washington DC's 293.

From an AQI of 51 onwards, air quality begins to be worrisome for human health.

The smoke has caused the cancellation of school outings and sporting events, and, on Capitol Hill, Pride celebrations planned by the White House have been called off.

Public health officials urged people to minimize their exposure to smoke as much as possible, since the air poses immediate and long-term health risks.

Some 111 million people were on alert this Thursday, at least in the US, according to the EPA.

Much of the cloud comes from Quebec, Canada, where hundreds of fires are burning.

A severe drought has made the current wildfire season historic, having started only a month ago.

How is air quality measured? What effects can smoke have on your body?

 

There's something in the air...
To a large extent, the air on our planet is made up of two gases that are vital for the development of life: nitrogen and oxygen.

To this great mass of O2 and N molecules, particles that are generated in all parts of the planet are added every day: either due to human causes, such as the burning of fossil fuels, or natural causes such as a forest fire or the explosion of a volcano

To measure those extra molecules, scientists use gauges that the US National Oceanic and Atmospheric Administration (NOAA) says are designed to identify five types of pollutants: tropospheric ozone, carbon monoxide, carbon dioxide, sulfur dioxide, nitrogen dioxide and airborne particles, known as aerosols.

Tropospheric ozone -in particular, surface ozone, that is, the one that exists on the Earth's surface- is molecularly identical to that found in the atmosphere (O3, that is, three oxygen molecules), and that protects us from the sun's harmful ultraviolet rays.

But on the surface, its effects on living things can be harmful.

 

Pollutants and their effects
Ozone is generated when sunlight reacts with certain chemicals (nitrogen dioxide or carbon monoxide) present in industrial or automotive emissions, NOAA explains.

In fact, according to the EPA, exposure to high levels of ozone would be related to the worsening (or even the origin) of diseases such as asthma.

"Ozone in the air we breathe can affect our health," the EPA says, "particularly on sunny days when ozone can reach harmful levels."

However, what we currently see off the northeast coast of Canada and the US are the effects of airborne particles, known as aerosols.

"These particles are small solid and liquid droplets suspended in the air," explains NOAA. "They can take flight at construction sites, forest fires, volcanoes, and some chemical reactions in the atmosphere."

The World Health Organization (WHO) associates aerosols with all kinds of respiratory diseases, and with the poor quality of health of certain po[CENSORED]tions.

"There is strong evidence of the negative impact on health associated with exposure to these contaminants," explains the WHO. "Most are sulfates, nitrates, ammonium, sodium chloride, coal, mineral dust, and water."

 

The scale

After measuring the presence of pollutants, scientists use a scale - with values ranging from 0 to 500 - to indicate air quality.

When the index number is within the range of 0 and 50, the air quality is considered "good."

Between 50 and 150, air quality is risky for people with health problems, such as respiratory or skin conditions, while numbers above 151 are considered "unhealthy" and the effects are noticeable in all po[CENSORED]tions, regardless no matter how susceptible a person is to contaminants.

In its recommendations on air pollution, the WHO highlights the importance of knowing air quality given its close relationship with health.

"The major sources of external pollution are beyond the control of individuals, and this requires concerted action among local, national and regional leaders working in the energy, transportation, waste management, urban planning and agriculture sectors."

 

https://www.bbc.com/mundo/noticias-65850714