the road to Belgrade, which has more than 23,000 inhabitants, and Dračevo, which has almost 20,000 inhabitants. Other large settlements are north of the city, such as Radišani, with 9,000 inhabitants, whereas smaller villages can be found on Mount Vodno or in Saraj municipality, which is the most rural of the ten municipalities that form the City of Skopje. Some localities outside the city limits are also becoming outer suburbs, particularly in Ilinden and Petrovec municipality. They benefit from the presence of major roads, railways and the airport, in Petrovec. Pollution Air pollution is a serious problem in Skopje, especially in winter. Concentrations of certain types of particulate matter (PM2 and PM10) are regularly over twelve times the WHO recommended maximum levels. In winter, smoke regularly obscures vision and can lead to problems for drivers. Together with India and Bosnia and Herzegovina, North Macedonia is one of the most polluted places in the world. Skopje's high levels of pollution are caused by a combination of smoke from houses, emissions from the industry, from buses and other forms of public transport, as well as from cars, and a lack of interest in caring for the environment. Central heating is often not affordable, and so households often burn firewood, as well as used car tyres, various plastic garbage, petroleum and other possible flammable waste, which emits toxic chemicals harmful to the population, especially to children and the elderly. The city's smog has reduced its air quality and affected the health of many of its citizens, many of which have died from pollution-related illnesses. An application called AirCare ('MojVozduh') has been launched by local eco activist Gorjan Jovanovski to help citizens track pollution levels. It uses a Traffic light system, with purple for heavily polluted air, red for high levels detected, amber for moderate levels detected, and green for when the air is safe to inhale. The application relies on both government and volunteer sensors to track hourly air pollution. Unfortunately, government sensors are frequently inoperable and malfunctioning, causing the need for more low-cost, but less accurate, volunteer sensors to be put up by citizens. Faults on government sensors are especially frequent when the pollution is measured is extremely high, according to the AQILHC (Air Quality Index Levels of Health Concern). On 29 November 2019, a march, organized by the Skopje Smog Alarm activist community, attracted thousands of people who opposed the government's