Air quality guidelines relate to four common air pollutants: particulate matter (PM), ozone (O₃), nitrogen dioxide (NO₂) and sulfur dioxide (SO₂).The WHO designates airborne particulates, a Group 1 carcinogen. The PM (inhalable coarse particles with a diameter between 2.5 µm and 10 µm, designated PM10 and PM_2.5) is the deadliest form of air pollution due to its ability to penetrate deep into the lungs and blood streams unfiltered, causing permanent DNA mutations, heart attacks, and premature death. WHO guideline limits for annual mean of PM_2.5　are 10 mg/m³. PM10 is primarily produced by mechanical processes such as construction activities, road dust re-suspension and wind, whereas the PM_2.5 originates primarily from combustion sources. An annual average concentration of 10 µg/m³ was chosen as the long-term guideline value for PM_2.5 by the WHO. These findings suggest that the health risks associated with short-term exposures to PM₁₀ produce an increase in mortality of around 0.5% for each 10 µg/m³ increment in the daily concentration. Therefore, a PM₁₀ concentration of 150 µg/m³ would be expected to translate into roughly a 5% increase in daily mortality.

Children are more vulnerable to air pollution because of their developing lungs. The number of alveoli increase from 24 million at birth to 257 million by 4 years. They breathe 50% more air per kg body weight. Studies from Poland have shown that an increase of 10 mg/m³　in PM₁₀　exposure was associated with a decrease in growth of FEV₁ of 84 mL/year. Besides the increased acute episodes of wheezing and respiratory infections, there is evidence of increased fetal loss, preterm deliveries and intrauterine growth retardation in prenatal exposure to air pollutants. In the great smog in 1952 in London, the infant mortality doubled.

An innovative experiment is being carried out in two South American cities to fight the spread of the Zika virus. Mosquitoes infected with the Wolbachia bacteria are to be released in large quantities in Rio De Janeiro in Brazil and Medellin in Colombia. These bacteria spread rapidly in the Aedes mosquito, and has the strange property of hindering the fertility of the host and rendering their offspring infertile. It also blocks the replication of the Zika and Chikungunya virus in the mosquito, and may also limit the spread of the Dengue virus. Experiments in Australia, Vietnam and Indonesia have found some measure of success. If successful, it will be a game changer in vector control and is being dubbed the biggest thing after DDT. (Nature 26 October 2016).