Air quality, haze and your photos

What haze takes away

Fine particles and moisture in the air scatter light, and the photo loses three things. In order of importance:

Contrast gets filled in. Scattered skylight leaks into the shadows and lifts them, so the frame looks as if it's under a layer of milk. That detail was never recorded. It isn't hiding in the file waiting to be pulled out.

Colour fades and shifts. Small particles scatter blue and violet more, so distant things go cool and blue. Larger particles or dust push the other way, towards yellow and orange. White balance in haze has no fixed direction. It depends on what's in the air that day.

Things look soft. The lens is fine. The low-frequency contrast has gone, and the eye reads that as blur. If nothing in the distance will look sharp however you focus, suspect the air first.

Distance is the real variable

What matters isn't the AQI number itself but how much air sits between you and the subject. At the same AQI, a portrait at twenty metres barely changes and a ridge eight kilometres away disappears. So long lenses suffer far more than wide ones, because long lenses are usually pointed at something far off.

Visibility and AQI are related but not convertible. High humidity makes the same particle load look worse. Go by actual visibility.

What you can change on the spot

1. Get closer. This works best. Halve the distance to the subject and you halve the air in between, and the contrast comes straight back.
2. Shoot into the light. Haze makes light visible. Shafts through trees at dawn and the glow of headlights on a bridge are things a clear day won't give you.
3. Use the layers. The fade from near to far is aerial perspective, as in Chinese landscape painting. Find a frame with clear foreground, middle and background outlines and let the tones carry the depth.
4. Go close, go small, shoot people. Macro, still life and street portraits are hardly affected, and the light is softer and more even.

A polariser cuts reflections from water and glass and deepens a blue sky a little, but it can't remove haze caused by particles. No filter will fix clarity.

How much editing can win back

Some of it. This order works best.

• Fix white balance first. Sample something that should be neutral grey, like concrete, tarmac or the shadow side of a cloud, then deal with contrast. The other way round, things get stranger the more you push.
• Go easy on dehaze. It's local contrast under another name, and it costs you shadow noise, oversaturation and banding in the sky. 15 to 30 is enough for most photos. Past 60 it usually looks dirty.
• Set the black point instead of adding contrast. Pull the blacks down until the darkest areas are truly black. The image clears up with fewer side effects.
• Work in zones. Add contrast and clarity only to the distant layer, and leave the foreground alone so the whole frame doesn't get crunchy.
• Keep some of the cast. Dense haze often turns distance cyan or dusty yellow, and forcing it back to neutral looks fake. Leaning into a cool or earthy grade often holds up better.
• Know when to stop. If the shadows on the far hills are already filled in, every algorithm just amplifies noise. Black and white is the more honest way out.

More important than the photo

When air quality is unhealthy, long stretches outdoors affect your breathing, more so for sensitive groups. Follow your local health advice, wear a proper mask if you need one, and cut the time outside.

In blowing sand or dust, avoid changing lenses outdoors. Back home, use a blower before you wipe, so you don't grind grit into the coating.