Despite the bright blue, sunny skies that much of Israel woke up to on Thursday morning, a fog of air pollution blanketed the country as a result of the previous night’s Lag Ba’omer bonfires.Although the pollution concentrations peaked between 10:30 p.m.Wednesday and 4:30 a.m. Thursday at most Environmental Protection Ministry monitoring stations, the smell of burnt materials still lingered throughout the morning.Recording dramatic increases in the concentration of particles that can pass to the human respiratory tract, the stations showed particularly problematic levels of PM2.5 – fine particulate matter with a diameter of 2.5 microns or less.On a normal day, the ministry explained, the concentration levels of PM2.5 amount to only about 50 percent of those of PM10 – particles with a diameter of 10 microns or less. However, as a result of the bonfires, concentrations of PM2.5 rose to about 75%-85% of those of PM10, ministry data said.Among the monitoring stations with the greatest concentrations of PM10 were those in Jerusalem’s Shmuel Hanavi neighborhood, Givatayim and the central moshav of Yad Rambam, according to the ministry.The Jerusalem neighborhood showed 348 micrograms per cubic meter, 5.8 times the city’s normal values, while Givatayim had 269 micrograms per cubic meter, 4.5 times the typical daily values, and Yad Rambam received 249 micrograms per cubic meter, 3.1 times its typical daily values. High levels of PM10 were also experienced in the south-central moshav of Nir Galim, with 224 micrograms per cubic meter, 3.7 times the typical daily values for the area. Not far behind were also Yavne, Rehovot, Petah Tikva and the northern neighborhoods of Tel Aviv.As far as PM2.5 is concerned, extremely high levels were recorded in both Jerusalem’s Shmuel Hanavi neighborhood and Bnei Brak near Route 4, the ministry said.While stations in the Jerusalem neighborhood measured 313 micrograms per cubic meter, 10.4 times the normal daily values, those in Bnei Brak found 304 micrograms per cubic meter – 10.1 times the normal daily values for the area.High levels of PM10 were also encountered in northern Ashdod, with 264 micrograms per cubic meter, 8.8 times typical daily values; in Rishon Lezion, with 253 micrograms per cubic meter, 8.4 times normal daily values; and in the southern moshav Nir Yisrael, with 250 micrograms per cubic meter, 8.3 times the levels of a typical day there.While a greater amount of research is available today regarding the environmental impacts of PM10, scientists believe that the much finer PM2.5 is more dangerous to human health.The ministry lists typical daily values of PM10 as 60 micrograms per cubic meter, and of PM2.5 as 30 micrograms per cubic meter, on average throughout the country.Concentrations of respirable particles in much of the Dan region’s stations were relatively low this year, as a result of the reduction of open spaces available for bonfires in this central area, the ministry said.In comparison to last year’s data on Lag Ba’omer, however, air pollution levels soared this year. Last year, the highest level of PM10 was recorded in Beersheba, with 146 micrograms per cubic meter, 2.4 times the city’s normal values. For PM2.5 last year, the highest concentration was in Nir Yisrael, with 242 micrograms per cubic meter – 8.1 times the typical values for the area.“It is important to note that particle concentrations that were measured are influenced by, among other things, the positioning of the bonfires relative to the monitoring stations and meteorological conditions, such as wind direction and speed and conditions of atmospheric turbulence,” a statement from the ministry said.