ZERO has been monitoring in detail the evolution of air quality in the cities of Lisbon and Porto, using the concentrations of nitrogen dioxide (NO2) measured at the air quality monitoring stations managed by the Regional Development and Coordination Commissions and whose Provisional data are made available by the Portuguese Environment Agency.
Nitrogen dioxide is an excellent indicator of pollution associated with human activity and has been used by several entities and universities worldwide to assess the impact of the drop in economic activity and mobility in air quality associated with restrictive measures imposed by air pollution control. covid-19 pandemic.
In cities, the measured nitrogen dioxide is mainly a direct consequence of the combustion processes that take place in vehicles, with greater responsibility for those who use diesel as a fuel that have higher emissions compared to gasoline vehicles.
Nitrogen dioxide in high concentrations causes effects ranging from irritation of the eyes and throat, to the affect of the respiratory tract, causing a decrease in respiratory capacity, chest pain, pulmonary edema and damage to the central nervous system and tissues.
The most sensitive groups such as children, asthmatics and individuals with chronic bronchitis are the most affected. This pollutant can also increase the reactivity to naturally occurring allergens.