I don’t understand how this is possible. The car engine is more efficient but the leaf blower would use a gallon or less of fuel that that amount of time as where the car would burn 30 to 40 times more that for the trip.
There’s many different types of pollution. One is CO2, for example. Other types are particulates, NOx compounds and so on.
Car engine systems and exhaust systems tend to release relatively small quantities of these other types of pollution, but a lot of CO2 and CO.
Leaf blowers tend to be fairly inefficient and have incomplete combustion, virtually no filters and no catalytic converter – so they release much less CO2 than cars, but much much more of the other pollutants.
When people say leaf blowers cause more pollution this is what they’re talking about. Note that many of these other compounds are more acutely hazardous to people and the local environment, while CO2 is obviously a fairly well noted hazard for the global environment.
Car engines have a catalytic converter, which reduces the amount if harmful pollutants released by the motor. Additionally, a leaf blower uses a two stroke engine while a car uses a four stroke engine. Two stroke engines, which are common configurations for small motors, combine the fuel and the oil together. This means some of the motor oil gets burned in the combustion process, causing the release of air pollutants.
In the specific instance you’re talking about, they were looking at “unburt hydrocarbons”, or essentially fuel/oils in the air.
Due to the nature of two-stroke engines, this is a inevitable result, but in four-stroke engines, it is nearly impossible. Thus, the levels are wildly higher with the leaf blower (vs the car).
The carbon monoxide and nitrogen oxide (the more common exhaust gas measures) were nothing unexpected (much more for the car).
The short answer is that they burn fuel much less efficiently and because they don’t have any of the fancy filters that cars have. Because they burn less efficiently they release more harmful byproducts like carbon monoxide.
Then, There is no catalytic converter on the leaf blower exhaust like a car has. So those bypeoducts are just release into the air. Unlike in a car where a lot of them are captured by the catalytic converter
If you burn fuel perfectly, then the only output you get is water and carbon dioxide, which are totally harmless to life (except as a greenhouse gas). But fuel never burns perfectly, and some engines are better than others at achieving it. It’s all the other stuff that gets created that is toxic – carbon monoxide, nitrous oxides, unburnt fuel, formaldehyde, benzine, and a million other harmful things that are produced in uncontrolled reactions.
Modern car engines are quite good at burning fuel properly, and the exhaust passes through something called a catalytic converter, which is designed to cause harmful substances to react into less harmful ones. As a result, car exhaust is relatively quite “clean” as long as it is working properly. In contrast, the small two-stroke engines used by things like leafblowers and lawnmowers are very very dirty, and launch all kinds of nasty stuff into the air.