Health impacts of air pollution

Ozone (O₃) is a powerful and aggressive gas. High levels of ozone corrode materials, buildings and living tissue. It reduces plants’ ability to conduct photosynthesis and hinders their uptake of carbon dioxide. It also impairs plant reproduction and growth, resulting in lower crop yields and reduced forest growth. In the human body, it causes inflammation in the lungs and the bronchia.

Once exposed to O₃, our bodies try to prevent it from entering our lungs. This reflex reduces the amount of oxygen we inhale. Inhaling less oxygen makes our hearts work harder. So for people already suffering from cardiovascular diseases or respiratory diseases like asthma, high-ozone episodes can be debilitating and even fatal. it can also lead to premature mortality. O₃ is also a greenhouse gas contributing to warming of the atmosphere.

Multiple human clinical studies, epidemiological studies and toxicological studies support a causal relationship between short-term exposure to airborne SO₂ and respiratory morbidity. The observed health effects have included respiratory symptoms, airway inflammation and increased emergency department visits and hospitalisations for all respiratory causes

NO₂ is the harmful component of NO_X and causes adverse effects on health: it can affect the liver, lung, spleen and blood. It can also aggravate lung diseases leading to respiratory symptoms and increased susceptibility to respiratory infection.

As with SO₂, NO_X contributes to acid deposition but also to eutrophication of soil and water. 

PM can cause or aggravate cardiovascular and lung diseases, heart attacks and arrhythmias. Exposure can harm people of all ages, but people with existing heart and respiratory problems are particularly at risk. It can also affect the central nervous system and the reproductive system, and can cause cancer. One outcome of exposure to PM can be premature death.

PM also acts as a greenhouse gas, mainly cooling the Earth's climate, although certain types of PM contribute to atmospheric warming. PM in the atmosphere can also alter rainfall patterns and affect the surface albedo properties of snow (the extent to which snow reflects light).