Olive Trees Combat Air Pollution, New Research Shows

VegPM, a Tuscan research project, proves that certain tree species can combat air pollution from particulate matter (PM) and improve air quality in urban environments.
Shanghai
By Francesca Gorini
Jan. 17, 2023 15:10 UTC

Olives are among the tree species that can best con­tribute to clean­ing the air, accord­ing to the results of VegPM, a research project coor­di­nated by the University of Florence. This project aimed to iden­tify the most suit­able indige­nous plants for com­bat­ing air pol­lu­tion caused by par­tic­u­late mat­ter (PM).

Launched in 2020 and sup­ported with 180.000 euros by the Cassa di Risparmio di Lucca Foundation, the VegPM project gath­ered data from four Italian munic­i­pal­i­ties in Tuscany affected by high lev­els of fine par­ti­cles: Lucca, Porcari, Capannori and Altopascio. In addi­tion to olive trees, the research team revealed that Laurel (Laurus nobilis), Privet (Ligustrum), Oleander (Nerium ole­an­der), Magnolia (Magnolia gran­di­flora) and Cherry lau­rel (Prunus lau­ro­cera­sus) could also improve air qual­ity.

Particulate mat­ter is a mix­ture of solid and liq­uid par­ti­cles – organic and inor­ganic. These par­ti­cles are dis­persed in the air and are highly dan­ger­ous for human health. Road traf­fic is the pri­mary PM source, but heat­ing sys­tems, waste man­age­ment and agri­cul­ture can also cause an excess of PM.

Particles are com­monly clas­si­fied by their diam­e­ter into three cat­e­gories: coarse” (PM10), fine” (PM2.5) and ultra­fine” (PM0.2). The size of the par­ti­cles deter­mines how they affect the res­pi­ra­tory sys­tem and enter the blood­stream.

See Also:Health News

Prolonged expo­sure to PM10, in par­tic­u­lar, can cause severe effects, such as car­dio­vas­cu­lar and res­pi­ra­tory dis­com­fort, chronic aller­gies, and even pre­ma­ture mor­tal­ity in chil­dren. Epidemiological stud­ies have also shown that the prox­im­ity of busy roads is asso­ci­ated with chronic res­pi­ra­tory dis­eases in chil­dren and the elderly. In an urban envi­ron­ment, these harm­ful effects can be inten­si­fied by dan­ger­ous heavy met­als caused by expo­sure to oils, tires, fuel, metal­lic paints and waste.

Therefore, devel­op­ing prac­ti­cal mit­i­ga­tion actions is one of the most crit­i­cal chal­lenges for local gov­ern­ments. Many munic­i­pal­i­ties have looked into design­ing effec­tive urban forests.” These require appro­pri­ate plant species to be planted along road­ways or near highly pol­luted areas. For this new strat­egy to work, the plants cho­sen should respond to water stress and con­tain CO2 lev­els.

The VegPM project makes the entire area encom­pass­ing Lucca, Porcari, Capannori and Altopascio – about 100 km² – the inno­v­a­tive urban green model test­ing loca­tion. Lucca, Porcari, Capannori and Altopascio have the high­est con­cen­tra­tions of PM10, nitro­gen diox­ide and ozone in all of Tuscany, accord­ing to the yearly regional air qual­ity map released by Arpat.

Some plant species can act as nat­ural fil­ters of par­tic­u­late mat­ter by inter­cept­ing and retain­ing par­ti­cles on their leaf sur­faces: Our goal was to iden­tify, test and select the most promis­ing among the native species of our cli­matic niche in order make them ideal can­di­dates for under­tak­ing local actions to sig­nif­i­cantly reduce air pol­lu­tion,” says project coor­di­na­tor Federico Martinelli, asso­ciate pro­fes­sor of Genetics at the Department of Biology of the University of Florence.

As a first step, we made an exten­sive screen­ing of the avail­able species capa­ble of adsorbing/trapping more PM, heavy met­als and ozone: We com­bined patho­phys­i­o­log­i­cal stud­ies with mol­e­c­u­lar analy­sis and geno­typ­ing tech­niques made avail­able by the sequenc­ing equip­ment avail­able in the Department of Biology of the University of Florence, so to under­stand the mol­e­c­u­lar mech­a­nisms that under­lie the mod­u­la­tion of pos­i­tive char­ac­ter­is­tics. Then, in 2021, in coop­er­a­tion with the National Research Council of Italy, we launched the exper­i­men­tal part of the project by set­ting up a net­work of six­teen con­trol units through­out the area, capa­ble of mon­i­tor­ing the main air pol­lu­tants and col­lect­ing both quan­ti­ta­tive and qual­i­ta­tive data. By inte­grat­ing the val­ues recorded by the mon­i­tor­ing cen­ters with the par­tic­u­late accu­mu­lated in the leaves of each species ana­lyzed, we were able to rank the species with the high­est PM depo­si­tion val­ues.”

Researchers picked sep­a­rate leaf sam­ples for every tree. The depo­si­tion val­ues of each PM frac­tion were com­pared and ana­lyzed against the aver­age par­tic­u­late mat­ter lev­els recorded through­out the year. Using this process, researchers could rank each species accord­ing to their abil­ity to accu­mu­late fine and ultra­fine par­ti­cles. They found that olive trees, in par­tic­u­lar, demon­strate a high accu­mu­la­tion capac­ity.

This fea­ture, along with their abil­ity to tol­er­ate stresses such as drought and salin­ity, makes them one of the most promis­ing can­di­dates. In urban con­text, their pres­ence is even more impor­tant because they nat­u­rally absorb car­bon diox­ide and release oxy­gen, essen­tial for the life of every human being.”

Given the exper­i­men­tal results of the VegPM project, the researchers hope that more research will be under­taken and show the abil­ity of cer­tain trees to negate the harm­ful effects of liv­ing in an urban envi­ron­ment.

For now, our stud­ies have focused only on exist­ing plants. But what would it hap­pen on new, planted plants? Would the PM con­cen­tra­tion decrease more? I hope this ques­tion could stim­u­late a fol­low-up of the project,” Martinelli adds.



Advertisement

Related Articles

Feedback / Suggestions