Air fil­ters to curb in­door pol­lu­tion tied to im­proved blood pres­sure

The Asian Age - - Science+ Health -

Lon­don, Sept. 15: Peo­ple ex­posed to even low lev­els of air pol­lu­tion are more likely to de­velop struc­tural changes in the heart that can be a pre­cur­sor to heart fail­ure, a UK study sug­gests.

While ex­po­sure to air pol­lu­tion has long been linked to an in­creased risk of heart at­tacks and strokes, less is known about how pol­lu­tants might al­ter the struc­ture and func­tion of the heart, the study team writes in Cir­cu­la­tion.

Re­searchers looked at data on ex­po­sure to traf­fi­cre­lated air pol­lu­tion and re­sults from heart MRIs for 3,920 adults who did not have car­dio­vas­cu­lar dis­ease. They found that pre­vi­ous ex­po­sure to tiny par­ti­cles known as PM2.5, which in­clude dust, dirt, soot and smoke, and to ni­tro­gen diox­ide, a poi­sonous gas in car ex­haust, were as­so­ci­ated with en­large­ment on both sides of the heart.

“Air pol­lu­tion ap­pears to be dam­ag­ing for car­dio­vas­cu­lar health even at a rel­a­tively low ex­po­sure level,” said lead study au­thor Nay Aung of Queen Mary Uni­ver­sity of Lon­don.

In­di­vid­u­als ex­posed to higher level of air pol­lu­tants were more likely to have larger car­diac ven­tri­cles ( main pump­ing cham­bers) af­ter ac­count­ing for po­ten­tial fac­tors that can in­de­pen­dently in­flu­ence the size of these cham­bers,

Se­niors liv­ing in hous­ing with poor in­door air qual­ity may have health­ier blood pres­sure when they use por­ta­ble air fil­ters than when they don't have these de­vices, a small ex­per­i­ment sug­gests.

Ex­po­sure to so- called PM2.5 — tiny par­ti­cles of dust, dirt, soot, and smoke — has long been linked to an in­creased risk of car­dio­vas­cu­lar dis­eases, re­searchers note in JAMA In­ter­nal Medicine. But less is known about whether por­ta­ble air fil­ters might help re­duce this risk.

The cur­rent study in­volved 40 non­smok­ers liv­ing in low- in­come hous­ing for se­niors in Detroit, Michi­gan. The res­i­dence was lo­cated

Aung said by email.

"This is im­por­tant be­cause these ob­served changes in the heart were sim­i­lar to the pat­terns seen in heart fail­ure de­vel­op­ment," Aung said.

To as­sess ex­po­sure to traf­fic fumes, re­searchers ex­am­ined data on av­er­age annual air pol­lu­tion lev­els at par­tic­i­pants' home ad­dresses at the start of the study.

Half of near ma­jor road­ways and in­dus­trial fa­cil­i­ties that re­lease fine par­tic­u­late mat­ter into the air.

Res­i­dents' blood pres­sure was mea­sured af­ter they used three dif­fer­ent types of por­ta­ble air fil­ters, each for three days at a time: a low- ef­fi­ciency air fil­ter; a high ef­fi­ciency par­tic­u­late ar­restance ( HEPA) fil­ter; and a sham fil­ter that didn't clean the air at all.

Com­pared to when they used the sham fil­ter, the se­niors' av­er­age ex­po­sure to PM2.5 in­doors was 31 per­cent lower with the low- ef­fi­ciency fil­ter and 53 per­cent lower with the HEPA fil­ter.

And with use of the air fil­ters, blood pres­sure lev­els in peo­ple with hy­per­ten­sion im­proved

were ex­posed to av­er­age annual con­cen­tra­tions of less than 9.9 mi­cro­grams of PM2.5 par­ti­cles per cu­bic me­ter of air ( ug/ m3) and 28.2 ug/ m3 of ni­tro­gen diox­ide.

For fine par­tic­u­late mat­ter, that's well within UK guide­lines lim­it­ing av­er­age ex­po­sure to no more than 25 ug/ m3 of PM2.5, although the World Health Or­ga­ni­za­tion ( WHO) has said there are no safe lim­its by an amount sim­i­lar to what might be achieved with life­style changes like in­creased ex­er­cise or re­duced salt con­sump­tion, said lead study au­thor Masako Mor­ishita of Michi­gan State Uni­ver­sity in East Lans­ing.

“A sim­ple in­ter­ven­tion us­ing in­ex­pen­sive in­door air fil­tra­tion units can help to lower both PM2.5 ex­po­sures and blood pres­sure lev­els,” Mor­ishita said by email. “Since hy­per­ten­sion is the lead­ing risk fac­tor for death world­wide, we be­lieve much larger tri­als are war­ranted to test whether fil­tra­tion units can play an im­por­tant role in help­ing to pre­vent car­dio­vas­cu­lar dis­eases world­wide.” for PM2.5 ex­po­sure, Aung and col­leagues note in Cir­cu­la­tion.

Re­searchers mea­sured par­tic­i­pants' heart struc­ture with MRIs a me­dian of 5.2 years af­ter as­sess­ing their air pol­lu­tion ex­po­sure.

For ev­ery ex­tra 1 ug/ m3 of PM2.5 and ev­ery ad­di­tional 10 ug/ m3 of ni­tro­gen diox­ide peo­ple were ex­posed to near their homes, their hearts were en­larged by ap­prox­i­mately 1 per­cent, the study found.

The type of en­large­ment seen in the study is a “well- rec­og­nized . . . adap­ta­tion herald­ing heart fail­ure de­vel­op­ment,” the au­thors note.

Heart fail­ure hap­pens when the heart mus­cle is too weak to pump enough blood through the body. Symp­toms can in­clude fa­tigue, weight gain from fluid re­ten­tion, short­ness of breath and cough­ing or wheez­ing. Med­i­ca­tions can help strengthen the heart and min­i­mize fluid buildup in the body.

The study wasn't a con­trolled ex­per­i­ment de­signed to prove whether or how air pol­lu­tion might di­rectly cause en­large­ment in the heart.

It's pos­si­ble that when peo­ple in­hale pol­luted air it causes in­flam­ma­tion in the lungs and blood ves­sels and fine par­tic­u­late mat­ter en­ters the blood­stream, said Ben­jamin Horne, di­rec­tor of car­dio­vas­cu­lar and ge­netic epi­demi­ol­ogy at In­ter­moun­tain Med­i­cal Cen­ter Heart In­sti­tute in Salt Lake City, Utah.

This can over­work the heart, Horne, who wasn't in­volved in the study, said by email.

“Even peo­ple who are free from car­dio­vas­cu­lar dis­ease may, over time, de­velop dis­eases due to chronic ex­po­sure to air pol­lu­tion,” Horne said.

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