The number of COPD sufferers throughout the world is an estimated 210 million, according to the World Health Organization. Risk factors that increase a person’s chance of developing COPD include:

Smoking is the biggest risk factor for COPD. Besides tar, nicotine, and carbon monoxide, tobacco smoke contains more than 250 other toxic chemicals. Over time, inhaling these harmful substances can cause damage to the airways that gradually progresses over time and result in lung irritation, inflammation, and loss of elasticity. This may also damage the lung’s protection and filter system.

This can be defined as inhaling the smoke exhaled by a smoker or the sidestream smoke from the end of a burning cigarette, cigar, or pipe. Secondhand smoke can expose you to the same harmful chemicals, toxins, and carcinogens as smokers themselves. According to the surgeon general, secondhand smoke does cause premature death and disease in children and adults who don’t smoke. There is no risk-free level of secondhand smoke; the only protection is to seek out 100 percent smoke-free settings: Going into another room, opening a window, or turning on the air conditioner do not eliminate risk.

Exposure to pollutants in the air released from motor vehicles and factories, or secondary pollutants like ground level ozone (the main component of smog) have been shown in numerous studies to exacerbate airway diseases like COPD. Workplace exposure to coal mine dust, silica, and a host of other harmful occupational agents can aggravate COPD, as can household pollutants such as dust, paint, cooking fumes and insecticides.

Some rare genetic deficiencies may make people susceptible to COPD. One rare inherited enzyme condition called alpha-1 antitrypsin deficiency can cause COPD. This condition creates an imbalance of proteins that can result in damage to the lungs. If people with this condition also smoke, COPD can progress much faster.