# NO 2 

# Pr imary NAAQS – Ov erview of

F inal Ru lemaking

1 Br iefing fo r OM B De cember 16 , 20 09 Of fice of Air an d Ra diation Of fice of Air Qu ality Pl anning an d St andards

# Ba ckground

• Cu rrent N O 2 

### NAAQS: An nual st andard , le vel is5 3 pp b, al l areas of U .S. are in attainment
• Ex isting NO 2 

### mo nitors (a bout 40 0 to tal) are pr imarily si ted tom easure area -wide co ncentrations
• NO co ncentrations ca n be3 0 - 100% hi gher ne ar ro ads th an aw ay from th e ro ad

2 

### • NO 2 

### co ncentrations ca n be3 0 - 100% hi gher ne ar ro ads th an aw ay from th e ro ad
• In dividuals wh o sp end ti me on o r ne ar ma jor ro adways (residence, sc hools, co mmuting) ca n ex perience sh ort- term NO 2 

### ex posures hi gher th an me asured byc urrent ne twork
• Sc hedule fo r on going re view

– De cember 16 , 20 09: Se nd draft of rule to OM B fo r in teragency re view

– Ja nuary 22 , 20 10: Co

urt sc hedule re quires si gnature of final ru le

# Ke

y Co nclusions from th e IS A an d RE A
• Th e ev idence re lating sh ort- term (m inutes toh ours) NO 2 ex pos ures to re spiratory mo rbidity wa s ju dged tobe su fficient to in fer a li ke ly causal re lationship

• Th is co nclusion iss upported bye pidemiologic an d ex perimental ev idence
• Ep idemiologic st udies (1 - to24 - hours)

– Ge nerally re port po sitive as sociations wi th re spiratory mo rbidity en dpoints, wi th a nu mber statistically si gnificant

3 – Ge nerally re port po sitive as sociations wi th re spiratory mo rbidity en dpoints, wi th a nu mber statistically si gnificant • Ma ny of

these st udies we re co nducted in a reas wi th NO 2 co ncentrations be low th ose al lowed by the cu rrent NAAQS

– Ev idence fo r re spiratory ef fects isconsistent (a ssociations re ported in n umerous lo cations wi th va ri ety of me thodological ap proaches) an d co herent (respiratory he alth ou tcomes are lo gically li nked to gether)

– NO 2 ef

fect es timates ge nerally re main ro bust in m ulti - pollutant mo dels • Ex perimental st udies (3 0 - minutes to3- hours)

– Hu man cl inical an d an imal toxicological st udies su pport th e pl ausibility of the li nk between NO 2 an d re spiratory mo rbidity re ported in e pidemiologic st udies

– Provide ev idence fo r ef

fects of N O 2 on l ung ho st de fense an d im munity, ai rway in flammation, ai rway re sponse

– A me ta - analysis of

h uman cl inical st udies re ported th at sm all bu t si gnificant in creases in n onspecific ai rway hy perresponsiveness we re ob served at 0 .1 pp b NO 2 fo r 60 - min ex posures in as thmatics.

# Ov erview of Fi nal NO 2 

# NA

AQS

• Ad ministrator ju dges th at cu rrent an nual st andard al one isn ot re qu isite to protect pu blic he alth wi th an a dequate ma rgin of safety, ba sed on

– Ep id emiologic ev idence fo r NO 2 - associated re spiratory ef fects in l ocations wh ere an nual average NO 2 co ncentrations we re be low th e le vel of the cu rrent an nual NO 2

4 an nual average NO 2 co ncentrations we re be low th e le vel of the cu rrent an nual NO 2 NA AQS

– Su pported by RE

A an alyses : Po licy as sessment ch apter concluded th at ri sks es timated tob e as sociated wi th ai r qu ality adjusted up ward to si mulate ju st me eting th e cu rrent st andard ca n re asonably beconcluded to bei mportant from ap ublic he alth pe rspective

– CASAC co ncurs wi th EP A s ju dgment th at th e cu rrent NA AQS do esn ot protect th e pu blic

# Ov erview of Fi

nal NO 2 

# NA

AQS (C ontinued)

• Le vel of n ew 1 - hour

standard: 10

pb

– Ba se d on bo th hu man cl inical an d ep idemiologic st udies, cons idered wi thin th e context of available in formation on the NO 2 co ncentration gradient around ro ads • Cl inical st udies: Th

e Ad ministrator co ncludes th at th e NO 2 - induced in creases in a irway re sponsiveness re ported fo r ex posures to NO 2 co ncentrations at o r ab ove 10 0 pp b co uld be ad verse fo r so me as thmatics; h owever, sh e al so no tes th at im portant un certainties ex ist wi th re gard tothe extent to wh ich th e re ported ef fects are ad verse

– Th erefore, sh e co ncludes th at a standard le ve l no hi gher th an 10 0 pp b isa ppropriate tor eflect a

5 – Th erefore, sh e co ncludes th at a standard le ve l no hi gher th an 10 0 pp b isa ppropriate tor eflect a ca utious ap proach toconsidering th e un certainty as sociated wi th th e NO 2 - induced in crease in a irway re sponsiveness, bu t th at th is un ce rtainty al sos upports se tting a standard le ve l no lower th an 10 0 pp b • Ep id emiologic st udies: Ba sed on av ailable in formation on the NO 2 co ncentration gradient around ro ads, a st andard le vel of 1 00 pp b fo r a standard re flecting th e ma ximum al lowable NO 2 co ncentration an ywhere in the area wo uld beexpected tom aintain area -wide NO 2 co ncentrations be low th ose me asured in lo cations wh ere ke y U. S. e pidemiologic st udies ha ve re ported as sociations wi th re spiratory - related em ergency de partment vi sits an d ho spital ad missions

– A group of

5 key U. S. ep idemiologic st udies provide ev idence fo r as sociations be tween NO 2 an d re spiratory - related em ergency de partment vi sits an d ho spital ad missions in l ocations wh ere 98 th pe rcentile 1 - hour da ily ma ximum NO 2 co ncentrations me asured at a rea -wide mo nitors ra nged from 8 5 to94 pp b

# Ov erview of Fi

nal NO 2 

# NA

AQS (C ontinued)

• Form: 98

th 

### percentile of

the 3 - year average of

the an nual di stribution of

1 - hour da ily ma ximum NO 2 

### co ncentrations
• Mo nitoring ne twork: To

m easure ma ximum NO 2 

### co ncentrations, a 2 - tiered NO 2 

### mo nitoring ne twork wi ll bee stablished, i ncluding bo th ne ar- road an d area -wide mo nitors

– Ne ar- road mo nitors wi ll be re quired wi thin 50 m eters of the ro ads ex pected tocause th e ma ximum NO co ncentrations in a n area (considering traffic vo lume, fl eet mi x, ro ad

6 ma ximum NO 2 co ncentrations in a n area (considering traffic vo lume, fl eet mi x, ro ad de sign, etc.)

– 167 n ear- road mo nitors in 1 43 areasa nd 52 a rea -wide mo nitors • 1 ne ar- road mo nitor in C

ore Ba sed Statistical Areas (C BSAs) wi th 35 0,000 or

m ore pe ople • A se cond ne ar- road mo nitor in C BS As wi th 2. 5 mi llion pe ople or m ore ORa ny CBSA th at ha s on e or m ore ro ad se gments wi th 25 0,000 An nual Av erage Da ily Tr affic (AADT ) co unts • 1 area -wide mo nitor in C

BS As wi th 1 mi llion or

m ore pe ople

– Ad ditional mo nitors ma y be re quired, att he di scretion of t he Re gional Ad ministrator, fo r example, if m aximum co ncentrations are ex pected to oc cur in l ocations ot her than ne ar a major r oad (e .g., mu ltiple sm aller ro ads an d/ or st ationary so urces)