* Carbon monoxide (CO): A colorless, odorless gas that can displace oxygen in the blood, leading to suffocation. It is highly toxic.
* Nitrogen oxides (NOx): A group of gases that contribute to smog, acid rain, and respiratory problems.
* Unburnt hydrocarbons (HC): These are essentially incompletely burned fuel molecules. They contribute to smog and can be harmful to human health.
* Sulfur dioxide (SO2): A colorless gas with a pungent odor that contributes to acid rain and respiratory problems.
* Particulate matter (PM): Tiny particles that can be inhaled deep into the lungs, causing respiratory problems and other health issues.
It's important to note that modern cars have catalytic converters that reduce the emission of these harmful gases. However, even with these devices, some emissions are still released into the environment.
Here's a breakdown of the harmful effects of each gas:
* Carbon monoxide: Blocks the oxygen-carrying capacity of red blood cells, leading to hypoxia (oxygen deprivation). Symptoms include headache, dizziness, nausea, and even death.
* Nitrogen oxides: Contribute to respiratory problems, particularly in people with asthma and other lung conditions. They also contribute to the formation of ground-level ozone, a major component of smog.
* Unburnt hydrocarbons: Can cause respiratory problems and contribute to smog formation.
* Sulfur dioxide: Can cause respiratory problems and contribute to acid rain, which can damage forests, lakes, and other ecosystems.
* Particulate matter: Can penetrate deep into the lungs and cause respiratory problems, cardiovascular disease, and even cancer.
The combustion of petrol in car engines also produces carbon dioxide (CO2), a greenhouse gas that contributes to global warming. While not directly poisonous, CO2 is a major environmental concern.
