What Color Is Your Sky?

To mark the International Day of Clean Air for blue skies on September 7 and the International Day for the Preservation of the Ozone Layer on September 16, the 366 Hope Footprints Campaign will run What Color Is Your Sky? Campaign throughout September and October.

The International Day of Clean Air for blue skies highlights the importance of clean air and calls for greater global awareness and action to tackle air pollution. In 2026, it emphasizes the need to address air pollution and climate change together, calling for action that delivers cleaner air, healthier lives, and shared prosperity.^UNEP

The International Day for the Preservation of the Ozone Layer raises awareness of the importance of the ozone layer, which protects life on Earth from harmful ultraviolet radiation, and encourages continued global efforts to protect it. This year’s theme, Global Action for a Cooler Planet, highlights the importance of global action to advance sustainable cooling, improve energy efficiency, and reduce greenhouse gas emissions.^{UNEP Ozone Secretariat}

The Color of the Sky: Sky Blue

When you picture the sky on a bright, clear day, what color comes to mind?

For many of us, the answer is sky blue.

The color we call “sky blue” takes its name from the clear blue sky itself. Shouldn’t we do our part to keep our skies just as clear and blue?

Yet the clear skies we often take for granted do not stay that way on their own. The electricity we use, the cars we drive, and the energy and resources we consume each day all affect the climate and air quality—and can even dull the color of the sky.

Climate Change and Air Pollution: Changing Our Skies

Climate change and air pollution are closely connected. Greenhouse gases and air pollutants released by burning fossil fuels affect both the climate and air quality. At the same time, extreme heat, droughts, and wildfires intensified by climate change can further worsen air quality.

Air pollution may not always be visible, but it has serious effects on human health and ecosystems. Air pollutants released into the atmosphere can be carried by winds across borders, affecting air quality far from their source. The World Health Organization (WHO) identifies air pollution as one of the leading environmental risks to human health worldwide.^WHO It estimates that the combined effects of outdoor and household air pollution are associated with about 7 million premature deaths each year.

What happens to the color of the sky when air quality deteriorates? In recent years, rising concentrations of particulate matter, including PM10 and PM2.5, have worsened air quality, while extreme weather conditions can increase the risk of wildfires. When the air fills with these fine particles and harmful smoke, air quality can deteriorate across wide areas, leaving the sky hazy and dull.

The Ozone Layer: A Protective Shield in the Blue Sky

The ozone layer, located high in the stratosphere, acts as an important shield against harmful ultraviolet radiation. It absorbs much of the sun’s harmful ultraviolet radiation, helping protect humans, plants, animals, and other life on Earth. When chemicals once widely used in refrigerants and aerosols were found to damage the ozone layer, countries around the world joined forces to address the problem. In 1987, the Montreal Protocol on Substances that Deplete the Ozone Layer was adopted to phase out ozone-depleting substances.^UNEP 

However, ozone is not always beneficial. Stratospheric ozone high above the Earth is good ozone that protects life below. In contrast, when air pollutants from vehicle exhaust and industrial activities react in sunlight near the Earth’s surface, they can form ground-level ozone, or bad ozone. Ground-level ozone can harm human health and plants and, together with other air pollutants, contribute to photochemical smog.

Since the adoption of the Montreal Protocol, international efforts to phase out ozone-depleting substances have continued, and the ozone layer is gradually recovering. Ground-level ozone, however, continues to threaten human health and air quality. The year 2026 marks the 10th anniversary of the Kigali Amendment, which calls for the global phase-down of hydrofluorocarbons (HFCs)—potent greenhouse gases—and accelerates the transition to more energy-efficient and sustainable cooling solutions.^{UNEP Ozone Secretariat} This underscores the need to transition to sustainable cooling solutions that meet our cooling needs while helping protect the future of our planet.

Erase Your Carbon Footprint and Paint the Sky Blue

What can we do in our daily lives to help keep the sky clear and blue?

We can erase energy waste by using less electricity, erase car trips by driving less, and erase food waste by wasting less food. Each small choice helps conserve energy and resources, reduce carbon emissions, and keep our air clean.

Now, erase your carbon footprint—and paint the sky blue in its place.

What Color Is Your Sky?

Take a moment to look up at the sky.

What color was the sky you saw today?

“Thank you for another clear, blue sky.” “The sky really is sky blue.”

Write a message of support for our blue skies, and take a beautiful photo with the sky as your backdrop.

■ Erase Electricity & Elevator Use, Paint the Sky Blue

Unplug unused devices or turn off power strips.

Take the stairs instead of the elevator.

■ Erase Car Trips, Paint the Sky Blue

Use public transportation instead of driving.

Walk or bike for short distances.

■ Erase Food Waste, Paint the Sky Blue

Don’t leave leftovers.

Keep your refrigerator organized, make a list of what you have, and buy only what you need.