Health & Environment
Air Pollution and Health
During combustion each fuel gives off differing levels of toxic greenhouse gases and consequently they have different impacts on public health.
The table below shows that vehicles using LPG emit the lowest levels of greenhouse gases.
What Gases are produced by Vehicles?
Carbon Monoxide CO
CO, is a colorless, odorless gas that is formed as a result of incomplete combustion of fuel and is a component of motor vehicle exhaust. A study In the US shows that cars contribute about 56% of all CO emissions. CO reduces the ability of blood to carry oxygen and can cause headaches, respiratory problems and, at high enough concentrations, death.
Carbon Dioxide CO2
Whilst this is a non toxic gas it is a contributing factor to climate change and global warming.
Oxides of Nitrogen (NOx)
Include several gaseous compounds made of nitrogen and oxygen emitted by both spark-ignition and diesel vehicles. Oxides of Nitrogen are lung irritants and can increase susceptibility to 
respiratory illness (especially asthma) and pulmonary infection. In addition, NOx contributes to the formation of ground level ozone, which is a major constituent of photochemical smog. Smog severely irritates the mucous membranes of the nose and throat, which can lead to coughing and even choking. It also impairs normal functioning of the lungs and long-term exposure may cause permanent damage.
Volatile Organic Compounds (VOCs) or Hydrocarbons (HC)
Are gaseous organic chemical compounds derived from diesel, gasoline and most alternative fuels which also contribute to the formation of ground level ozone. As well as being emitted from the tailpipe of motor vehicles, these compounds are also released to the atmosphere in vehicles during refueling, through evaporation via leaks in fuel filler caps, hot engine parts or failures in a vehicle’s on-board vapour recovery systems. LPG and CNG systems, because they are pressure sealed, do not displace any vapour's during normal operation and only release very small quantities during refueling
Fine Particulate Matter (PM)
Is emitted by both diesel and spark ignition engines, though diesel sources tend to dominate. In 1998 the California Air Resources Board (CARB) determined diesel particulates to be a Toxic Air Contaminant. In 2002, after much research, the US EPA concluded that PM in diesel exhaust causes acute throat and bronchial irritation, poses a chronic respiratory hazard to humans, and is a likely carcinogen. Particles may also adsorb potentially health-threatening organic air toxic's found in engine exhaust.
The following graph illustrates the gaseous breakdown when comparing Petrol to LPG where LPG vehicles overall produce some 40-60% less greenhouse gases. (Based on overseas emission testing of vehicles that meet the stringent Euro 3 emissions regulations)
To illustrate the amount that this impacts the environment and our health well take a look at C02 levels produced by both Petrol and LPG. This varies from vehicle to vehicle and is affected by many things, the age/ condition of the vehicle, the condition of the catalytic converter, the ‘tune’ of the engine etc. for the practicality of this example we will look at the Co2 output of a typical 6 cylinder Australian produced Ford Falcon / Holden Commodore using an average of 17.8 litres per 100km on LPG and 13.5 litres per 100km on petrol.
To calculate the C02 output values you need to know two things for each fuel, (1) the mass of C02 produced for burning each litre of fuel (Kg of C02 per litre) and (2) the number of litres of fuel consumed over 100 kilometers under identical operating conditions. Multiply (1) by (2) and divide by 100 and you will calculate the amount of C02 gas produced per kilometer of travel for each fuel.
The Australian greenhouse office website states that the mass of C02 gas released from the exhaust pipe by the burning of one litre of fuel is as follows:
Petrol 2.3kg
LPG 1.5kg
Based on the calculations above the C02 emissions per kilometer are:
(1.5*17.8) /100 = 0.26 kg/km
(2.3*13.5) /100 = 0.3105 kg/100km for petrol vehicles
Traveling a distance of 25,000 km per year will not only save you $2487* per annum in your fuel bill but you will be saving the Environment 1262.5KG of C02 production, not to mention the other harmful greenhouse gasses such as NOx, HC etc. This information is illustrated below.
Are older vehicles fitted with LPG as environmentally friendly?
Based on the results of the Federal Governments own test programs which indicate that tail pipe C02 emissions produced by older cars (pre 1993) fitted with LPG are still some 14% lower than their petrol powered counterparts.
** Prices based on consumption data as per the NSW environmental Protection Authority’s vehicle emissions testing consumption rates (1996) and petrol priced @$125c/ Litre, LPG @38.9c/L. Fuel consumption of 13.5L/100km on petrol and 17.8L/100km on LPG traveling and annual distance of 25,000km.
Data extract from the report ‘LPG the clean transport alternative’ commissioned by ALPGA Sep 2003, written by Peter Anyon BSc Mech Eng. Click here to visit this report on the ALPGA website.
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Website last updated:
07-Jul-2010
