▁c ough ing , ▁and ▁difficulty ▁breath ing ▁from ▁ac ute ▁expos ure ▁to ▁sympt oms ▁such ▁as ▁irregular ▁heart be at , ▁lung ▁cancer , ▁kid ney ▁disease , ▁chron ic ▁bron ch itis , ▁and ▁prem ature ▁death ▁in ▁individuals ▁who ▁suffer ▁from ▁pre - ex isting ▁card i ov asc ular ▁or ▁lung ▁dise ases ▁due ▁to ▁chron ic ▁expos ure . ▁The ▁sever ity ▁of ▁health ▁effects ▁generally ▁depends ▁upon ▁the ▁size ▁of ▁the ▁particles ▁as ▁well ▁as ▁the ▁health ▁status ▁of ▁the ▁individual ▁exposed ; ▁older ▁adult s , ▁children , ▁pre gn ant ▁women , ▁and ▁imm uno comp rom ised ▁populations ▁are ▁at ▁the ▁greatest ▁risk ▁for ▁ad verse ▁health ▁out comes . ▁Short - term ▁expos ure ▁to ▁partic ulate ▁poll ution ▁has ▁been ▁linked ▁to ▁ad verse ▁health ▁impact s . ▁ ▁As ▁a ▁result , ▁the ▁US ▁Environment al ▁Prote ction ▁Agency ▁( E PA ) ▁and ▁various ▁health ▁ag encies ▁around ▁the ▁world ▁have ▁established ▁th resh olds ▁for ▁concentr ations ▁of ▁PM 2 . 5 ▁and ▁PM 1 0 ▁that ▁are ▁determined ▁to ▁be ▁acceptable . ▁However , ▁there ▁is ▁no ▁known ▁safe ▁level ▁of ▁expos ure ▁and ▁thus , ▁any ▁expos ure ▁to ▁partic ulate ▁poll ution ▁is ▁likely ▁to ▁increase ▁an ▁individual ' s ▁risk ▁of ▁ad verse ▁health ▁effects . ▁In ▁European ▁countries , ▁air ▁quality ▁at ▁or ▁above ▁ 1 0 ▁micro gram s ▁per ▁cub ic ▁meter ▁of ▁air ▁( μ g / m 3 )