To drive 1100 miles, the commenter above gave an extremely generous 25 gallons of gas (likely closer to 40 for a non-Prius).
One gallon of gas produces about 20 pounds of CO2, which is about 73% oxygen (from the atmosphere) by weight. The remaining 27% of the weight comes from carbon.
So, one gallon of gasoline provides 20*0.27=5.4lbs of carbon to the CO2 produced. Multiply by 25, and you're looking at over 135lbs of carbon alone coming from your source when 25 gallons of gas are burned.
Considering that the amount of weight carried around by the user of a leaf blower is on the low tens of pounds, and not hundreds, it seems ludicrous to presume that a leaf blower produces anywhere near the amount of CO2 in an hour as does a car driving 1100 miles.
Even without the oil - 2-stroke engines will run on straight petrol, albeit briefly - they still emit an obscene amount of unburnt fuel.
This is the table in the source:
+--------------------+-------------------+-------------+---------------+
| | Exhaust Emissions | New vehicle | Older vehicle |
+--------------------+-------------------+-------------+---------------+
| Hydrocarbons | 199.26 | 0.39 | 201.9 |
| Carbon Monoxide | 423.53 | 15.97 | 1310 |
| Particulate Matter | 6.43 | 0.13 | 0.78 |
| Fugitive Dust | 48.6-1031 | N/A | N/A |
+--------------------+-------------------+-------------+---------------+
> Another way to visualize the data is to compare emissions for a given amount of leaf blower operation to miles traveled by car. The Air Resources Board regularly publishes such emissions benchmarks. Thus, for the average 1999 leaf blower and car data presented in Table 9, we calculate that hydrocarbon emissions from one-half hour of leaf blower operation equal about 7,700 miles of driving, at 30 miles per hour average speed. The carbon monoxide emission benchmark is signficantly different. For carbon monoxide, one-half hour of leaf blower useage would be equivalent to about 440 miles of automobile travel at 30 miles per hour average speed.
So will old ones, if you run them on the right fuel.
My 25-year-old Range Rover has a 4.6 litre engine adapted to run on propane which is - under the right circumstances - a *negative* emission vehicle. It can have measurably less CO and HC in the exhaust than in the intake air (city air heavily contaminated with CO and HC for example from bus engines).
Perhaps this is true for certain types of air pollution, but there's no way it's true for carbon emissions. CO2 emitted has to be proportional to gasoline burned. And there's no way a leaf blower is consuming 25 gallons of gas per hour.