The World Health Organization says nine out of 10 people worldwide are breathing high levels of contaminants from both outdoor or ambient and household air pollution، as the Technical Timessaid. Outdoor air pollution alone killed approximately 4.2 million people in 2016. Household air pollution، meanwhile، killed an estimated 3.8 million people within the same period. Particulates in the contaminated air could penetrate deep into lungs and cardiovascular system. They can cause diseases such as stroke، heart disease، lung cancer، chronic pulmonary diseases، and respiratory infections including pneumonia. According to WHO، outdoor air pollution levels are lowest in high-income countries located in Europe، the Americas، and the Western Pacific. Nevertheless، the pollution in these countries has lowered the average life expectancy by anywhere between two and 24 months. The highest outdoor pollution levels were noted in Eastern Mediterranean Region and in Southeast Asia. The annual mean levels of pollutants in these countries have often exceeded more than five times the limit set in WHO's air quality guidelines. Meanwhile، more than 90 percent of deaths related to air pollution was seen in low-income and middle-income countries، particularly in Asia and Africa. It is followed by low-income and middle-income countries of the Eastern Mediterranean Region، Europe، and the Americas. Household air pollution is comprised of contaminants acquired from fuel and technology used during cooking such as the stove، heating، and lighting paraphernalia. WHO has particularly monitored the use of wood، charcoal، animal dung، coal، and kerosene as fuels for cooking. An estimated 3 billion people or more than 40 percent of the world's population still have no access to suitable cooking devices. This could mean that there are more than 3 billion people who are breathing toxic smoke while they cook food in their homes، says Tedros Adhanom Ghebreyesus، director general of WHO. The inaccessibility to sustainable cooking apparatus was apparent in sub-Saharan Africa. WHO noted that household air pollution is associated with increased mortality and morbidity from acute lower respiratory infections among children. As for adults، household air pollution has been linked to cardiovascular disease، chronic pulmonary disease، and lung cancer. WHO says that more than 1،000 cities were added to its ambient air quality database since 2016. To date، a total of 4،300 cities in 108 countries are now included in WHO's database.