Scientists are a step closer to understanding what drives fine particles in the Earth's atmosphere after identifying new links between natural contaminants and human pollutants.
Fine particles are pollutants that can adversely affect human health when levels in the air are too high and can also affect the climate.
This breakthrough could lead to stronger and more accurate climate legislation and cleaner air for researchers to say. The international team, led by Manchester University and the Forschungszentrum Jülichhung in Germany, explored the impact of the secondary organic aerosol (SOA) in our atmosphere.
SOA contains very small particles and is produced in an atmosphere of natural and artificial emissions. They are made by complex interactions between sunlight and volatile organic compounds from trees, plants, cars or industrial emissions.
These tiny particles seriously affect the physical and mental health of people and are the main factor of premature deaths every year for about 5.5 million people around the world. The influence of these particles on the climate is also responsible for the greatest unfavorable uncertainty for human effects on the radiation balance affecting climate change.
The international team studied the formation of fine SOA particles from different pairs emitted from natural plants, and from artificial vapor mixtures and natural vapor responses in the laboratory. In all cases, they found that a smaller mass of particles was produced when the same amount of steam was reacting in the mixture than when reacting on its own.
The lead author, Professor Gordon McFiggans of the Manchester School of Earth and Environmental Sciences, explains: "It has long been known that when predicting a number of secondary pollutants such as ozone, we need to consider the whole vapor mixture.
"Our findings now show that we also need to know what the real atmosphere is in humans and naturally occurring trace compounds to quantify particle pollution."
The study is the first study of its kind that focuses on the effect of these complex vapor mixtures on the mass concentration of atmospheric particles.
Professor Thomas Mentel, co-author at FZJ, added: "With careful designing, we have been able to understand two different ways of reducing the amount of particulate matter in blends, and we have found that trace compounds not only compete for the reactant but also the products of these reactions can themselves react to prevent the formation of effective particles.
"By including this experimentally observed effect on the global air quality model, we have shown that the mass of fine particles can be significantly affected under real atmospheric conditions, not only in the laboratory."
This observational quantification of the interaction between vapors that can form particles provides a first glance at how pollutants will work in complex mixtures found in the real atmosphere.
Professor McFiggans concluded: "Our work provides an indicative plan to understand the future contribution of particles to air quality and climate by integrating these results and results from other experiments into numerical models, and we will be able to give the right advice to policymakers."