Air pollution
Air pollutants are not always visible and come from a wide variety of sources.
"In recent years, practically the entire Spanish and European population has been
breathing polluted air, which does not meet the standards recommended by the World
Health Organization (WHO)," begins the report on Air quality in the Spanish State
during 2023 by Ecologistas en Acción, funded by the Ministry for the Ecological
Transition and the Demographic Challenge. Despite decades of progress, air quality in
most Western countries, such as Spain , is still poor .
The reasons for the recent decline in air quality remain unclear, the agency says, but
may be linked to a high number of wildfires , a warming climate and rising human
consumption patterns driven by population growth and a strong economy. The long-
term outlook is also unclear, even as politicians debate air pollution rules.
What is air pollution?
Air pollution is a mixture of particles and gases that can reach harmful concentrations
both outdoors and indoors. Its effects can range from increased risk of disease to
increased temperatures . Soot, smoke, mold, pollen, methane, and carbon dioxide are
just a few examples of common pollutants.
In the U.S., one measure of outdoor air pollution is the Air Quality Index, or AQI, an
index also measured in Spain , which rates air conditions across the country based on
concentrations of five major pollutants: ground-level ozone, particle pollution (or
particulate matter), carbon monoxide, sulfur dioxide, and nitrogen dioxide. Some of
these also contribute to indoor air pollution , along with radon, cigarette smoke,
volatile organic compounds (VOCs), formaldehyde, asbestos, and other substances.
A danger to global health
Poor air quality kills people. Worldwide, bad outdoor air caused an estimated 4.2
million premature deaths in 2016, about 90% of them in low- and middle-income
countries, according to the World Health Organization. Indoor smoke is a constant
threat to the health of the 3 billion people who cook and heat their homes by burning
biomass, kerosene and coal. Air pollution has been linked to higher rates of cancer,
heart disease, stroke and respiratory diseases such as asthma. In the United States,
nearly 134 million people – more than 40% of the population – are at risk of getting
sick and dying prematurely from air pollution, according to estimates by the American
Lung Association. And in Europe, although there has been a decline in the number of
premature deaths from air pollution, it remains the greatest environmental risk to
health.
While these effects arise from long-term exposure, air pollution can also cause short-
term problems , such as sneezing and coughing, eye irritation, headaches and dizziness.
Particles smaller than 10 micrometers (classified as PM10 and the even smaller PM2.5)
pose greater health risks because they can be breathed deep into the lungs and into
the bloodstream.
Air pollutants cause less direct health effects when they contribute to climate change .
Heat waves, extreme weather, disruptions in the food supply, and other effects related
to increased greenhouse gases can have negative impacts on human health. The Fourth
U.S. National Climate Assessment released in 2018 noted, for example, that a changing
climate “could expose more people in North America to ticks that carry Lyme disease
and mosquitoes that transmit viruses such as West Nile, chikungunya, dengue, and
Zika.”
(Related: How does air pollution affect our brain and other organs? )
Environmental impact
Although many living things emit carbon dioxide when they breathe, the gas is
considered a pollutant when associated with cars, airplanes, power plants, and other
human activities that involve burning fossil fuels like gasoline and natural gas. That's
because carbon dioxide is the most common greenhouse gas, which traps heat in the
atmosphere and contributes to climate change. Over the past 150 years, humans have
pumped enough carbon dioxide into the atmosphere to raise levels above those seen
for hundreds of thousands of years.
Other greenhouse gases include methane (from landfills, the natural gas industry and
gases emitted by livestock) and chlorofluorocarbons (CFCs), which were used in
refrigerants and aerosol propellants until they were banned in the late 1980s because
of their ozone- depleting effect .
(Related: A revolutionary law to reduce methane emissions and help climate change )
Another pollutant linked to climate change is sulfur dioxide, a component of smog .
Sulfur dioxide and related chemicals are best known for causing acid rain . But they also
reflect light when released into the atmosphere, blocking sunlight and creating a
cooling effect. Volcanic eruptions can spew large amounts of sulfur dioxide into the
atmosphere, sometimes causing cooling that lasts for years. In fact, volcanoes used to
be the primary source of atmospheric sulfur dioxide; today, it's people.
Airborne particles, depending on their chemical composition, can also have direct
effects other than climate change. They can alter or deplete nutrients in soil and
waterways, damage forests and crops, and deteriorate cultural icons such as
monuments and statues.
