Urban air pollution is a complex mix of gases and particulate matter that negatively affect communities living in and around urban areas. It’s most recognisable by that thick brown haze which blankets cities across the world, especially in summer, known as photochemical smog.
Nitrogen dioxide, ground-level ozone and particulate matter are the three main air pollutants in modern cities and the health effects of these are well-documented. These three, as well as carbon monoxide and sulfur dioxide, are known as ‘criteria pollutants’. Criteria pollutants are included in national air quality standards that define allowable concentrations of pollutants in ambient air.
Why measure nitrogen dioxide
Inhalation of nitrogen dioxide (NO2) can impair lung function and increase susceptibility to infection, particularly in children. It can also aggravate asthma. NO2 is not only a toxic gas but it is also a precursor to several harmful secondary air pollutants such as ozone and particulate matter. It also plays a role in the formation of acid rain and photochemical smog.
Why measure ozone?
In the upper atmosphere ‘good’ ozone (O3) protects life on Earth from the sun’s ultraviolet rays. At ground level ‘bad’ ozone is a criteria pollutant that is a significant health risk, especially for people with asthma. It also damages crops, trees and other vegetation and is a main component of smog.
Why measure particulate matter?
In 2013, the World Health Organisation (WHO) classified particulate matter (PM) as carcinogenic to humans, responsible for the deaths of 3.7 million people worldwide per year. PM10 (particles ≤ 10 microns) is a criteria pollutant and is a serious health risk because PM10 particles can penetrate the lungs. PM2.5 (particles ≤ 2.5 microns) is also a criteria pollutant which has even greater health impact due to risk of penetration deeper into the respiratory system. Research has linked particulate pollution to lung and heart disease, strokes, cancer, and reproductive harm.
Why measure carbon monoxide and sulfur dioxide?
Carbon monoxide (CO) is a toxic, odorless gas. If inhaled it will displace oxygen from the hemoglobin molecule in our blood and lead to severe disability or even death. Sulfur dioxide (SO2) is a toxic gas with a strong irritating smell. Inhaling sulfur dioxide has been associated with respiratory disease and difficulty breathing. It is also a precursor to acid rain and atmospheric particulates.