What Color Is Air?

Air is generally transparent and colorless. This means it doesn't absorb or reflect specific wavelengths of visible light, unlike objects that appear colored. As University of Alberta physicist John Davis explains, if air had a color, it would mean it absorbed or canceled out a portion of the visible light spectrum (e.g., grass is green because it absorbs blue and yellow light).

While air itself is colorless, cultural and symbolic associations often assign it a color.

• Purple: Some individuals associate air with purple, likely due to its connection to the sky and mystical representations. (Reddit thread)
• Yellow: In certain occult Western symbolism, yellow represents air. (Reddit thread)
• Faint Blue: Large volumes of air, like the atmosphere, can appear faintly blue due to Rayleigh scattering of sunlight. (Physics Stack Exchange)

The Color of Air in Specific Contexts

It's important to note that the color associated with "air" can vary drastically depending on the context:

• Air Quality Indicators: Air quality indices (AQI) don't directly assign a color to the air itself, but use colors to represent different levels of air pollution. These colors represent the risk associated with air quality, not the inherent color of the air. (AirNow.gov)
• Vehicle Decals: Clean air vehicle decals utilize different colors yearly for identification purposes. Again, these colors are for identification, not reflection of air's color. (California Air Resources Board)
• Compressed Air Lines: Color-coded air lines in machinery are used for identification of different air systems (e.g., brake systems), not to represent the air's color. (TruckersReport.com)

Conclusion

In its pure form, air is colorless and transparent. However, various contexts and symbolic associations may attribute different colors to it.