Say the word smoke in Bali and you have about a minute before somebody points at the road. Look at the traffic. Look at the trucks. What's one cigarette next to that.
It's a fair point, and it gets treated as an opinion, which is why the argument never ends. It's a question with an answer, and here is how the answer was reached.
They put a car and three cigarettes in the same garage
Chiavenna, a small town in the mountains of northern Italy, chosen because the outdoor air there is usually clean. A private garage of 60 cubic metres, with a vented door so air kept moving through.
They shut the door, started a diesel car and left it idling for half an hour. Then they opened up for four hours to clear the place out. Then they lit three cigarettes and let them burn down over the same half hour, with the analyser three metres away at chest height.
In the hour after the engine started, fine particles averaged 31 micrograms per cubic metre. In the hour after the cigarettes were lit, 319.
There's a second number that gets quoted less and matters more. The engine at its worst roughly doubled that day's outdoor level. The three cigarettes hit fifteen times it, and then the air just stayed there. An hour and a half later the room was still above the outdoor limit, and that's where the record ends, because that's when they stopped measuring. Turn a key and an engine stops putting anything in the air. A cigarette put out ninety minutes earlier was still in that room.
Why that isn't as strange as it sounds
A truck is enormous. A cigarette is the size of your finger. The number sounds wrong until you say the obvious things out loud.
You are never standing where the exhaust is. Traffic smoke reaches you after it has already spread out into the whole outdoors. A cigarette burns a metre from your face, at table height, in the air you're already breathing, thinned by nothing at all.
Engines have also had thirty years of people trying to fix them. Filters, cleaner fuel, emissions rules, testing. A cigarette has had none of that, because there is nothing between it and the room.
And you know this already without an instrument. An hour in Denpasar traffic and your shirt comes home smelling of nothing much. Twenty minutes next to one person smoking and you carry it around all day.
The steelworkers made the same argument
A decade later the same research unit got a second run at it, in a study published in 2016, and this time the people making the traffic argument were not teenagers looking for a comeback.
The Marcegaglia steel factory in Ravenna employs more than 700 people, and in March 2014 it banned smoking in the outdoor areas across the site. Some of the workers pushed back with almost word for word what you'll hear in a Canggu café. They worked in a yard where heavy trucks load and unload steel all day. Banning one cigarette outdoors there wasn't going to change the air they were standing in.
You can see why they'd think that. So the researchers came out and tested it in front of them. They piped a truck's exhaust into a site office through the window and ran the engine for eight minutes with the door shut. Then they aired the office out, and someone who worked in that office and smoked in it every day came in and smoked two cigarettes over eight minutes.
Room | What was burning | Fine particles in the air |
|---|---|---|
60 m³ garage, Chiavenna | Diesel car, idling 30 minutes | 31 |
60 m³ garage, Chiavenna | Three cigarettes, 30 minutes | 319 |
36 m³ site office, Ravenna | Heavy truck, idling 8 minutes | 251 |
36 m³ site office, Ravenna | Two cigarettes, 8 minutes | 592 |
Micrograms per cubic metre. Chiavenna figures are hourly averages, Ravenna figures are averaged across two trucks with the background subtracted.
The results went to the whole workforce afterwards. Hard to argue with a number produced by your own truck, in your own site office, in front of you.
So which one is actually worse?
It depends what you're asking, and the two answers point opposite ways.
Across a city over a year, it's the traffic and it isn't close. Millions of engines running all day. A source apportionment study by Vital Strategies and the Bandung Institute of Technology, sampling across Jakarta in 2019, put as much as 57 per cent of the city's fine particles down to vehicle exhaust in the dry season. Nobody here is going to stand in Denpasar traffic and tell you the scooters are fine. When we say smoke, exhaust has always been part of what we mean.
In the air you are personally breathing, right now, at this table, it's the cigarette. Distance beats size. A bonfire on the next island doesn't bother you. A bonfire in your garden does.
One honest caveat, because a movement that overstates things is no use to anyone. Both experiments were closed rooms with a fixed amount of air, which is exactly why both columns look so alarming. Outdoors, the engine and the cigarette both vanish into a much bigger volume.
Here's what we think, and you're welcome to argue with it. The traffic argument is true, and it usually turns up as a way of ending the conversation rather than having one. Air doesn't run on credit. A dirty sky doesn't buy anyone a cigarette at the next table, it just means you're breathing both.
You didn't vote for the road, and it isn't going quiet this decade. The table next to yours is the one bit of that air anyone still gets a say in.
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World is already smoky enough.
Go Smokeless.
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