For years a secret killer has been attacking us, posing a threat to our health and causing lung cancer. According to recent research, the very air we breathe is working against us.

Before the International Agency for Research on Cancer declared that air pollution was a carcinogen, major components – such as the burning of fossil fuels – that factor into producing air pollution have been considered harmful and capable of causing cancer.

However, air pollution itself had never been deemed a carcinogen. Even the risk of developing lung cancer through air pollution is higher than the risks posed by smoking cigarettes, or even being exposed to ultraviolet radiation, because its sources are extremely common. In light of these new dangers, things as ordinary as the use of cars, buses, and power plants can lead to air pollution.

“We consider this to be the most important environmental carcinogen, more so than passive smoking,” said Kurt Straif, head of the IARC department that evaluates cancer-causing substances.

What air pollution does is that it takes a combination of harmful substances, including gases, which can later dump small, cancer-causing particles into the lungs. Because it is such a silent killer, it can be more worrisome. It has also been proven that pollution can increase the chances of having respiratory and heart diseases.

It would be ideal to have clean air, but the reality is that it is hard to maintain a clean environment when so many people don’t worry enough to preserve it.

“There are effective ways to reduce air pollution and, given the scale of the exposure affecting people worldwide, this report should send a strong signal to the international community to take action without further delay,” said Christopher Wild, director of the IARC.

There are small steps that people can take to help preserve clean air, such as driving smaller or electrical cars which release fewer fumes. However, that is something that needs to be controlled on a much bigger scale. Straif suggests that government officials take it upon themselves to improve the air we breathe.

The U.S. isn’t the only country that is under these conditions; China and India are currently the most polluted metropolises in the world. However, China is taking steps to lower pollution because it has been hurting their inflow of tourists.

Because it has been deemed the most dangerous carcinogen, it is necessary that action be taken in order to prevent the spread of pollution.