Dirty windows can harbor potentially dangerous pollutants behind protective layers of fatty acids from cooking emissions, which can linger for extended periods of time.
According to a recent study headed by University of Birmingham experts, the fatty acids found in cooking emissions are very persistent and difficult to break down in the environment.
Grimy windows could be harboring toxic pollutants
Kevin McCutcheon/Unsplash
That is, when they collide with a solid surface, such as a window, they form a self-organized thin film that accumulates over time and is only slowly broken down by other chemicals in the environment, as per ScienceDaily.
During this process, the film becomes rougher and attracts more water from the air's humidity.
Furthermore, harmful contaminants can become trapped behind this persistent crust and so shielded from degradation in the atmosphere.
According to senior author Dr. Christian Pfrang, the fatty acids in these films are not particularly dangerous in and of themselves, but since they are not broken down, they effectively shield any other contaminants that may be trapped behind.
The research, which appears on the front cover of Environmental Science: Atmospheres, was conducted in collaboration with specialists from the University of Bath, Diamond Light Source, ISIS Neutron and Muon Source, and the Institut Laue-Langevin in France.
The researchers worked on laboratory proxies, which are material samples produced in the lab to resemble "real world" materials.
These were spun into super-thin pollution sheets a few tens of nanometers thick.
The researchers studied the nano-scale composition of the films as well as changes in their surface patterns using neutrons and X-rays.
The researchers were also able to simulate the behavior of the films over time by adjusting the humidity and quantity of ozone - a critical pollutant both indoors and outdoors.
They discovered that the self-organized organization inside the films in repeating molecular sheets, known as the lamellar phase, made it impossible for smaller molecules, such as ozone, to access the reactive regions of the fatty acids within these structures.
When the films were formed and subjected to ozone, their surfaces were less smooth and more likely to absorb water, a result that has consequences for the creation and lifespan of aerosols in the atmosphere.
Around 2.4 billion people worldwide continue to cook using solid fuels (such as wood, agricultural waste, charcoal, coal, and dung) and kerosene on open flames and inefficient stoves, as per the WHO.
The vast majority of these people are impoverished and reside in low- and middle-income nations.
Access to cleaner cooking options differs significantly between urban and rural locations: in 2020, just 14% of individuals in metropolitan areas relied on polluting fuels and technology, compared to 52% of the worldwide rural population.
Household air pollution is caused by the use of inefficient and polluting fuels and technologies in and around the house, which emits a variety of health-damaging pollutants, including microscopic particles that enter the bloodstream after penetrating deep into the lungs.
Indoor smoking levels of fine particles can be 100 times higher than permitted in poorly ventilated buildings.
Women and children, who spend the most time around the household fireplace, are particularly vulnerable.
Reliance on polluting fuels and technology also necessitates a large amount of time spent cooking on inefficient equipment, as well as obtaining and preparing fuel.
Every year, 3.2 million people are killed prematurely as a result of diseases induced by home air pollution produced by the incomplete combustion of solid fuels and kerosene used for cooking.
Particulate matter and other contaminants in-home air pollution irritate the airways and lungs, decrease the immunological response, and diminish the blood's oxygen-carrying capacity.
Among the 3.2 million fatalities caused by home air pollution are:
32% are related to ischemic heart disease: exposure to home air pollution is responsible for 12% of all fatalities due to ischaemic heart disease, accounting for almost a million premature deaths per year.
23% are due to stroke: roughly 12% of all stroke fatalities can be related to daily exposure to domestic air pollution caused by the use of solid fuels and kerosene at home.
Lower respiratory infections account for 21% of all pneumonia fatalities in children under the age of five: exposure to home air pollution nearly doubles the incidence of childhood LRI and accounts for 44% of all pneumonia deaths in children under the age of five.
