Stage Effects & Haze

What it is, what’s in it, and what it means for you

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If you’ve ever noticed a fine atmospheric mist drifting through the light beams during one of our shows, that’s theatrical haze. We occasionally hear from audience members who are concerned about it, so we wanted to take a moment to explain exactly what it is, what’s in it, and why we’re confident it’s safe for the vast majority of people — including most of those with respiratory conditions.

Why do we use haze?

Haze is a standard tool of professional theatre. Its purpose isn’t to create a dramatic “foggy” effect — it’s much more subtle than that. Haze fills the air with microscopic airborne droplets that make light beams visible. Without it, spotlights and moving lights cut through the air invisibly; with it, you see those shafts of light that give a production its atmosphere, depth, and visual drama.

Think of it like dust motes caught in a sunbeam — except far finer, clean, and carefully controlled. If you’ve ever watched a West End production and wondered how the lighting looks so cinematic, haze is almost certainly part of the answer.

What’s actually in it?

We use Le Maitre PureHaze fluid, one of the leading professional haze products in the industry. Unlike many atmospheric effects used in theatre, it contains just two ingredients:

A food-grade polyol — a naturally-derived sugar alcohol (the same broad family of compounds used in food manufacturing, pharmaceuticals, and cosmetics) — and demineralised water. That’s it. No solvents, no petroleum-derived compounds, no synthetic fragrances.

The fluid is classified under COSHH (Control of Substances Hazardous to Health) as having no significant hazard to people or the environment under normal conditions of use. It contains no substances with a Maximum Exposure Limit under UK health and safety regulations. It is also readily biodegradable.

Is it the safest haze on the market?

We believe it’s among the very safest available, and there’s a specific reason for that. Not all theatrical haze fluids are the same. Many cheaper or older systems use glycol-based fluids — triethylene glycol or propylene glycol — which have been the subject of occupational health research. Studies of entertainment industry workers with prolonged exposure to glycol-based haze have found associations with throat irritation, vocal effects, and in some cases reduced lung function over time.

Le Maitre specifically designed PureHaze as an alternative to glycol systems precisely because of these concerns. The sugar-based formula avoids glycols entirely. Le Maitre themselves note that “alternative systems using triethylene glycol based hazers have been found to cause respiratory, nasal, throat and vocal irritation” — something PureHaze was formulated to prevent.^[1]

Le Maitre has also participated in independent safety research commissioned by theatre industry bodies including ESTA (the Entertainment Services and Technology Association) and Environ International Corporation, the consultancy engaged by Actors’ Equity in the United States to study the health effects of theatrical smoke and haze on performers.^[2] Those studies concluded that as long as exposure remains within established limits — which it does, at normal theatrical usage levels — there should be no harm to health. Bear in mind that performers are onstage, in close proximity to haze equipment, for multiple shows a week over extended runs. An audience member seated in an auditorium for a two-hour show is exposed to a small fraction of what even those studies deem acceptable.

What about haze versus smoke?

It’s worth being clear about what haze is not. It is not smoke. Smoke involves combustion and produces particulate matter — the kind of airborne particles that do cause respiratory irritation and are rightfully a concern for people with breathing conditions. Haze is a fine water-based aerosol: tiny droplets suspended in air, not combustion particles. The difference matters enormously from a health perspective.

SDC no longer uses traditional pyrotechnics in our productions. When you see atmospheric effects on our stage, it is haze — not smoke, and not anything involving combustion.

I have asthma, COPD, or another respiratory condition — should I be concerned?

That said, we don’t want to dismiss anyone’s concerns, because we know that highly sensitive airways can react to a wide range of airborne substances — including things as innocuous as perfume, dusty curtains, or even cold air. If your respiratory condition is severe or you know that any airborne particle tends to affect you, that’s worth taking into account when planning your visit.

A few things that may help:

Seating position matters. Haze is concentrated on and near the stage. Seating further from the stage, particularly in the rear of the auditorium, will mean lower exposure. Our front-of-house team are happy to advise on seating if you let us know your concerns.

We control it carefully. Haze is not running constantly throughout a show. It’s used in specific moments for specific scenes, and our technical team manage levels with care. It is not pumped into the auditorium continuously.

You’re always welcome to get in touch in advance. If you have a known respiratory condition and you’re unsure whether attending a particular show is right for you, please contact us before booking. We can tell you how prominently haze features in that production and help you make an informed decision. We’d always rather have that conversation than have someone uncomfortable during a show.

In summary

The haze you see at SDC productions is a carefully chosen, food-grade, water-based product with an excellent safety profile — among the safest options available in professional theatre. It is not smoke. It is not a chemical fog. At the levels used in an auditorium, the overwhelming weight of independent research indicates it is safe for the vast majority of audiences, including those with common respiratory conditions.

We take our audiences’ wellbeing seriously, which is why we wanted to be open about exactly what we use and why. Theatre should be a joyful experience for everyone — and we hope this gives you the confidence to settle back, enjoy the show, and let the lighting do its job.