Air Pollution

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مسشل۳) -) Geverd 

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) Pvbutcct ۱ ۰ ‏موم وه راومه یمود وه و ولو و‎ ۱ ar , whick adversely ders the ‏لاس هه بط رمرم‎ he kedls, he oowPon, or the Pood chat, or by teterPertey wit the property udues oF people. © poltedt vac be sold (large or sub-wolevuar), quid or yas . ٩ ‏لسن هم( عم رو‎ or wohropoyeus source (or bots). he estioded that why opoyeds sources have chong the ‏ماه‎ ‎OP dob ur by bese tot 0.00%. owever, tis widely wepied trot puedo ‏موی له و‎ cod hove o ‏تلو‎ averse ePPevt oo he code, epospstew und species vo the phocet. ‎these oe utd rok, vz70e to te luwer ukvospkere, ord‏ و طسق ‎Photochewiod scovy.‏ 

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Copied: dey atmasphere by volume aw pts pia ane Gas ‏هد‎ ‎Niuean (NG) 780.840 ppm (7AM) Oxven(O:) 200.460 ppv (2199696) 9:30 pen (040%) 35 po Nam (Ne 1818 ppm Haum(He) 524 ppm Matene(CH) 25 pw ‏یی‎ LM ppv Tying (055 ppm ‘Noticed in abovedry atmexphae ‏عست جر‎ ‏ات سوت‎ SS Sieon Atmospheric Water Vapor. ‘Minar components of air iste above ince: BOS ‏سرون‎ ‎xeon 000 pm ‘wane 0010 007 perm BRU 902 py ‎mw‏ 001 صقن ‎eaten ‏#كت نهد‎ 

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0.001818% 

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Global atmospheric concentration of CO2 lion (ppm) 1870 1680 1890 1900 1910 1920 19% 1840 1950 1960 1970 1980 1990 2000 Rin @) Sous T ier Seip, Maus oa Obs, Hove, ats ct cerca (SI ‏هه مه ما هطاحا هه هآ‎ 

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(ppm) Atmospheric Carbon Dioxide from Law Dome Ice Cores 340 320 300 280 1 1 1 1 1 1 1 1 L 1 1000 1200 1400 1600 1800 2000 Year (AD) 

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2000 1990 1980 Year 1970 1960 370 360 350 340 330 320 310 300 290 280 1950 C02 Concentration ppm 

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Cautionary Statements None required. None required. Persons with existing heart or respiratory ailments should reduce physical exertion and ‘outdoor activity General population should reduce vigorous outdoor activity Elderly and persons with existing heart or lung disease should stay indoors and reduce physical activity. General population should avoid vigorous outdoor activity Elderly and persons with existing diseases should stay Indoors and avoid physical exertion. General Health Effects None for the ‘general population. Few or none for the general population. Mild aggravation of symptoms among Susceptible people, with iritation symptoms in the healthy population. Significant ‘aggravation of symptoms and decreased exercise tolerance in| persons with heart or lung disease; widespread symptoms in the healthy population. Early onset of certain diseases in ‘addition to significant ‘aggravation of ‘symptoms and Psi Descriptor Good Moderate Unhealthfu Very Unhealthul Hazardous Index Value upto 50 50 to 100 100 to 200 200 to 300 over 300 

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۲۸8۶ 72 ‏روم‎ VALUES AND AIR QUALITY DESCRIPTORS PSI value Descriptor 0-50 Good 51-100 Moderate 101-199 Unhealthful 200-299 Very unhealthful =300 Hazardous TABLE 7.3 POLLUTANT STANDARDS INDEX (PSI) BREAKPOINTS 24-h TSP 24-hr SO, TSP x SO, gin? g/m? 10° (ug/m?)? 0 0 = 75 80 = 260 365 7 375 800 65 625 1600 261 8-hr CO mg/m? 0 5 10 17 34 1 0 ۰ Heim? 0 118 235 400 800 Index 0 50 100 200 300 Source: 40 CFR (Code of Federal Regulations) 58, 1982. 

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Table 2. Carboxihemoglobin levels resulting from steady-state exposure to increasing concentrations of CO in ambient air CO in COHb in Signs and symptoms atmosphere blood (%) (ppm) 10 2 ‘Asymptomatic 70 10 No appreciable effect, except shortness of breath on vigorous exertion; possible tightness across the forehead; dilation of cutaneous blood vessels. 120 20 Shortness of breath on moderate exertion; occasional headache with throbbing in temples 220 30 Decide headache; irritable; easily fatigued; judgment disturbed; possible dizziness; dimness of vision. 350 - 520 40-50 Headache, confusion; collapse; fainting on exertion 800 - 1220 60-70 Unconsciousness; intermittent convulsion; respiratory failure, death if exposure is long continued 1950 80 Rapidly fatal Source: Winter and Miller (1076), Elanhom and Barceloux, 1908 (Ref. 6) 

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14 co ppm 12 400 ‏و‎ 0 ‏و‎ 8 6 4 2 9 ppm CO ‏وس سسا‎ th lt ‏ال‎ ‎0 1 2 3 4 5 6 7 8 9 10 Exposure time (hr) Figure 7.4 Percent COHb plotted from (7.1) for sedentary activity. 35 ppm CO is the federal I-hr standard; 9 ppm is the 8-hr standard. 100 ppm is nat uncommon in heavy traffic. 

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‎GPRevts oP Otroyed Oxides‏ مور ‎Ghorttersn exposure ot wweder tra 9 pure per ‎Courediraices fess thos S pp coc iio hop. Cowrdindices os bow us ©.0 pp couse tua iritaion ord ‏وال بووین‎ decreuses to buoy Puociios to ostiuics. ‎boepiersa lower level exposures con destroy fucy tissue, lead to ewphysews. ‎ ‎aioe‏ هن و( ‎be especidly secsiive to the‏ موه رون مان ‎oxides.‏ 

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Otker ۳۳ ۱ tive veyeivd of vero powerdvd. @PPRevis tackide: — Cruustay ewes to Poll. — Reductay yous rue. ٠ Deteriorute Rubrics und Pade dyes. 9 Conde wetds (due to oiree gules Porced * Reduce visblip. 

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Oter @PReve (Coukned) * Onxtdes oP uiroyes, to he preseuce oP Sunidhi, ‏او مد ون‎ wits kydroourboes, ۳ photockhewicd oxidads pr sxr7y. * Ob, QOOx ts 4 precursor ty ute previpitaicd, ‏مار‎ say oP Pect bots tenresirid cad aquatiz 52251151575. 

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GuPuor Dioxide Ore-Pur perced oP pohuica retted sur oxide ewissious are ta the Porow oP suPur doxtde (GO,), 3 kewy, colorless yor vis ac odor tke o struck wuts. Dh yos vowbiees eosty wil wer vapor, Porsotacy wervsvb oP sWPunns wid (0,), uovbress, Dh bquid wap thea cowbiee wih oxyyed to the ur, Porseiey the eve wore ‏یخی وروی له رم‎ ‏60و ناك) لد‎ (١ 

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.عبت ماس - ‎(WG) gos‏ آدج مجحب حسطع ريراك ۶ Oote: The wot oP GO, relewed Prow cod Pred Power phous depeads oa tee suPur coded oP ool, oD P% ow O% by werh. Aik uP ur vod soweives pods us work uw O% suPur by wet. 1a Tada, suPur pooted ty quite low. 

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Welk ‏ت۳۳‎ oP GuPur Oxtdes * Gur donde wt ody kes 0 bad odor, ‏لا‎ coo ito the respirdipry sysiew. ۰ Gxposert to high pouvedruives Por skort periods oF ‏اوه من روط‎ the brooch cad teoreuse wurmes Alow, sohtay breathtay dPPicult. * Ohidres, the eer, those wi chrodr bray deur, an wikvulics ue espechiy susceptible to hese ‏و(‎ 

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GuPur dioxide ‏وه موی‎ ٠ ‏وا رزوی‎ the frog ocd fhrod of pooedrdives 

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GuPur doxtde toads ty have wore tone oP Peis ‏لنپ راهم عبت ارت‎ sold wervepb, und paticdkies ure uso presed. (1s he pot, tous oP ‏تمه‎ ‎deuhs vocured ig aeus where GO, cowedrdiows exceeded | pa oro Pew wwouk breuhers, e.y., people Why ore exervisiay or who have heud ookbs. Dheve ef Pevs tack: ‎problews, suk os episodes oP browhits requirtay hosptdtzaios‏ وبا ‎wwevrited wi lbwverevel od pouwedirdioe.‏ ‎respirciory ‎yeverd popvktiza.) ‎Cubevive spwptws, suck os headaches ood couse, to he ubseoe oF ‏ی هط مس‎ dur to bapterw expose. 

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GuPur vatdes GPRevts va Place Gur ‏یز رای مر‎ won phot species und vorteties, bots ive vod pultvoted. Gower oP the wot srusiive plaice tachide vious powwerckdy vdueble pues, leyuves, red ocd black voks, white usk, dPoPa aad blackberry. The ePPevts tochide: Otsible tajury to the wost secsiive phos of exposures ws bw ‏جد‎ ‎0:09 ‏فصا © ۳ موم‎ Otsible tajury to swonp viker phoot pes oP tiercvedite secetivily ot exposures oP O.OO ppew Por 0 hows. مدصي ‎Prow low levels, tra very Pew spevies‏ لالج هوق ‎dePtect sols.‏ له و 

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Otker ۳۳ * ‏موی‎ to SUP donde powrdruios were te Dorrsivs oF wets, provubly through the Porcvuiod pF wits. (GO, ‏و و‎ to whic depvsiivs.) GuPur oxides way dev dawg sioce und wosvoryp, po, vorivus Pers, puper, feuker, vod eleviricd 777۳17 * ‏لش تا تایه موه 60 لوص صا‎ visibly. ‏۳و بای رنه لول‎ whick & derived Pro ‏و نا وروی مرو یلو‎ 0 oF he ۱ ‏هم مت ی رز سم‎ 

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Weeds GPPRevts vP O2vur ۰ ‏ورین‎ we su powerPl respirdiory imac of the Poured to covet ‏مات لت اه‎ 

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World's Primary Air Pollutants—Thetr Sources and Effeets on Human Health ee Known or suspected effect Fuel-rich and Reduces the oxygen- stoichiometric carrying capacity of the combustion mainly blood by combining from motor vehicles with haemoglobin, thus deprives tissues of O> High-temperature Cause eye, throat, and combustion mainly lung irritation. Primary from motor vehicies pollutants that produce photochemical smog and acid rain, destroy ozone at the stratosphere Coal, and fossil Breathing difficulties burning . Coal combustion, ore Causes eye, throat, and smelters, petroleum lung irritation, Primary refineries, and diesel pollutants that engines produce acid rain Natural source Unnoticeable Lightning and bacterial activity in soils Forest fires, wind erosion, and volcanic eruptions Volcanic eruptions and decay Pollutant Carbon monoxide (CO) Nitrogen oxides (NO) and (NOp) Particulates Sulfur dioxide (SO) 

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Ozone Lightning and Product of ‘Causes eye, throat, and 00 photochemical photochemical Jung irritation, impairs. reactions in the reactions in * Jung function troposphere photochemical smog Carbon dioxide Animal respiration, Fossil-fuel and wood Partly responsible for the (C02) decay, and release combustion atmospheric greenhouse from oceans effect Hydrocarbons Biological processes Incomplete Primary pollutants that other than combustion and * produce photochemical methane (VOCs), volatiles smog ic., volatile organic compounds. 0 Methane Anaerobic decay, Natural-gas leak and Partly responsible for the (CHa) chewing animals combustion atmospheric greenhouse (cows, sheep. ete.), effect and oil wells Chlorofluorocarbons None Used as solvent, Destroy ozone at the (CFCs) aerosol propellant, streicsphere, thus and refrigzrent reduce the ozone UV protective layer em ae 

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Tage 3.2. Sources and Sinks of Primary Carbon Compousds in the Atmosphere Typical Concentration Life time Sinks Background Polluted 350 ppmv 350 ۷ Sy ocean <SOppbv 150-200 ppbv 1-2 m Oxidation to CO, 1650 pytv 21800 ppv = 10y Oxidation to 00 soils few ppb variable variable Photochemical teactions ‏هید هیر اه‎ ۱۷ — Wet and Dry deposition 0.2 pg m-* ‏وراد‎ ۱۷۶ Wetand Diy deposition Majorsources —-C produced (Ty) Ocean, biosphere 78x 108 fossil Fuels Biomass burning 660 transportation photochemistry Animals, decaying 610 Vegetation, wetlands vegetation Anthropogenic variable Secondary ‘small photochemistry Biomass burning small Anthropogenic Comipound Carbon dioxide (co) Carbon monoxide (co) Methane (chy) Nonmiethane hydrocarbons (NMHC) Particulate ‘organic Carbon (roc) Elemental Carbon (E Data from Warncck (1988), Smiil (1955), Roulie et (1982), 

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‎Sources and Sinks of Major Nitrogen Compounds in the Atmosphere‏ 34 تفر ‎Concentrations Lifetime Sinks ‎ ‎Compound Major N Produced ‎sources (Tey) Background Pelleted Ammonia Animals, Soil, 4 0.1 ppbv >6 ppbv 6d Conversion (NH) biomass burning to NH, Ammonium Conversion 65 005 ‏“شير كا< “سوير‎ Sd Wet and Dry (NHy+) from NHy deposition nitrous oxide Soil 4 310 ppbv 10y stratospheric (N20) photochemistry Nitric oxide (NO) and Fossil fuels, 48 100 prev <100 ppby ‏ل2>‎ oxidation to Nitrogen dioxide (NOs) lightning, HNO, =NO, biomass burning, NO; ‎soil, Oxidation Photodis- ‎of NO to NO2 sociation Nitrate Secondary 0 OS pgm? — S10 pe ‏سس‎ 54 Wet and Dry ۸0«( from NOe deposition ‎Data from Warneck (1983), Logan (1993), Smil (1585), ‎ ‎ ‎ 

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Sources and Sinks of Primary Sulphur Compounds in the Troposphere Major SProduced Typical Concentration Lifetime Sinks Sources (Tgy) “Background” Polluted Soils, Coastal 4a 500 pty = 44 years Photochemistry marshes, (slow), Oceans Biomass burnigg Stratosphere Oceans. Soils 1.6 1530 pty 100-200 ppt 12days_ Photochemistry 1 produces S02 Ocean algal 22:56 <I0ppty 100مماك‎ 0.6 days. Deposition to ocean, decomposition Osidation to S02 Bacterial variable 30-100 ppty* 330-810 piv. 4.44lays_ Photochemical reduction, reactions Soils and wetlands Anthropogenic, 103-2490 pptv >Sppby 24 days Wet and dry volcanoes, deposition, Oxidation of HS Oxidation to SO,*- Sea spray 138 OL peSm-? >25ygSm-* b week Wetant dry Oxidation from SO deposition tropical soil and tidal fats, TABLE 3.5, Carbonyl Sulphide (COS) Carbon Disulphide (CSy) Dimethyl Sulphide, DMS ((CH,)2S) Hydrogen Sulphide (HRS) Sulphur Dioxide (802) Sulphate (S0,-) > 1000 pp! ‘Sources: Moller (1984a, b), Warneck (1988). 

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1 ,اهنا )1984( 2500 10000 nocturnal low winds fracturing of tank accident ‘methylisooyani 1۲۸0 6.4, Air Pollution Disas:ers Londen (1952) 4000 > 20000 elderly at first anticyclonic inversion and fog river plain domestic coal burning S03 and smoke Poza Rice, Meaico (1950) 2 320 all ages nocturnal inversion, low winds coastal sulphur recoverye accident كول Donora, Pennsylvania (1984) 15 $900 elderly anticyclonic inversion and fog river valley steel and zine manufacture SO; and smoke Meuse Valiey, Belgium, (1930) Mortality and morbidity deaths © ill 6000 "Age groups ofected ‏راغ‎ ‎Weather ‎anticyclonic ‎inversion ‎and fog Geographical setting river valley Sources steel and zine manufacture Pollutants S03 and smoke وس ‎a‏ ما 

Air Pollution General Definition Air pollution may be defined as the presence in the air (outdoor atmosphere) of one or more contaminants or combinations thereof in such quantities and of such durations as may be or tend to be injurious to human, animal or plant life, or property, or which unreasonably interferes with the comfortable enjoyment of life or property or conduct of business. Air Pollutant It is a substance or effect dwelling temporarily or permanently in the air , which adversely alters the environment by interfering with the health, the comfort, or the food chain, or by interfering with the property values of people. A pollutant can be solid (large or sub-molecular), liquid or gas . It may originate from a natural or anthropogenic source (or both). It is estimated that anthropogenic sources have changed the composition of global air by less than 0.01%. However, it is widely accepted that even a small change can have a significant adverse effect on the climate, ecosystem and species on the planet. Examples of these are acid rain, ozone in the lower atmosphere, and photochemical smog. Composition of dry atmosphere, by volume ppmv: parts per million by volume Gas Volume Nitrogen (N2) 780,840 ppmv (78.084%) Oxygen (O2) 209,460 ppmv (20.946%) Argon (Ar) 9,340 ppmv (0.9340%) Carbon dioxide 375 ppmv (CO2) Neon (Ne) 18.18 ppmv Helium (He) 5.24 ppmv Methane (CH4) 1.745 ppmv Krypton (Kr) 1.14 ppmv Hydrogen (H2) 0.55 ppmv Not included in above dry atmosphere: Water vapor typically 1% (highly variable) Mean Atmospheric Water Vapor. Source for figures above: NASA. Carbon dioxide and methane updated (to 1998) by IPCC TAR table 6.1 [1]. The NASA total was 17 ppmv over 100%, and CO2 was increased here by 15 ppmv. To normalize, N2 should be reduced by about 25 ppmv and O2 by about 7 ppmv. Minor components of air not listed above include: Gas Volume nitrous 0.5 ppmv oxide xenon 0.09 ppmv ozone 0.0 to 0.07 ppmv nitrogen 0.02 ppmv dioxide iodine 0.01 ppmv carbon trace monoxide Na t i o n a l Amb i en t Ai r Qu a l i t y St a n d a rd s Po l l u t a n t Pri m a ry St d s. Av e rag i n g Ti m es Carbon Mo noxid e 9ppm (10 3 mg /m ) 35p p m 3 (40mg/m ) 1.5µg /m 3 8-h ou r1 0.053ppm 3 (100µg/m ) 3 50µg /m Ann ua l (Ari t hmet ic Mean) 2 Ann ua l (Ari t h. Mean) 1 24-ho u r 3 Ann ua l (Ari t h. Mean) 4 24-ho u r 8-h ou r5 Le ad Nit rog en Dio xi d e Part icu lat e Mat t e r (PM10) 3 Part icu lat e Mat t e r (PM2.5) 150u g/m 3 15.0µg /m 3 Ozo ne Sulfur Oxid es 1 65u g /m 0.08p pm 0.03p pm 0.14p pm ------- 1 Sec o n d ary St d s. Non e 1-h ou r Non e Qua rt e rl y Avera ge Same a s Primary Same a s Primary Same a s Primary Same a s Primary Same a s Primary Ann ua l (Ari t h. Mea n ) ------1 24-ho u r ------3-h ou r1 0.5p p m 3 (1300ug/m ) Not t o b e exceed ed more t ha n o nce per year. 2 To at t ai n t h is st an d ard , t h e 3-ye ar a vera ge of t h e we i g ht e d an nu a l mean PM10 concen t rat i o n at each mo nit o r wit hi n a n are a mu st no t e xceed 50ug /m 3. 3 To at t ai n t h is st an d ard , t h e 3-ye ar a vera ge of t h e we i g ht e d an nu a l mean PM2.5 co ncent rat io n s 3 from si ngle or mult ip le commun it y-orie nt ed mo ni t ors must n o t e xce ed 15.0u g/m . 4 To at t ai n t h is st an d ard , t h e 3-ye ar a vera ge of t h e 98th p erce nt i le o f 24-h our con cent ra t i on s at 3 each p o pu la t io n -o ri en t ed moni t or wi t h i n an are a must n ot excee d 65u g /m . 5 To at t ai n t h is st an d ard , t h e 3-ye ar a vera ge of t he fo u rt h -h ig he st d a i l y maximum 8-hour a vera ge o zo ne co nce nt rat i o n s measure d at e ach monit or wit hi n an area o ve r ea ch year must n ot excee d 0.08ppm. I ndex Value PSI Descriptor General Cautionary Statements Health Effects Up to 50 Good None for the general population. None required. 50 to 100 Moderate Few or none for the general population. None required. 100 to 200 Unhealthful Mild aggravation of symptoms among susceptible people, with irritation symptoms in the healthy population. Persons with existing heart or respiratory ailments should reduce physical exertion and outdoor activity. General population should reduce vigorous outdoor activity. 200 to 300 Very Unhealthful Significant aggravation of symptoms and decreased exercise tolerance in persons with heart or lung disease; widespread symptoms in the healthy population. Elderly and persons with existing heart or lung disease should stay indoors and reduce physical activity. General population should avoid vigorous outdoor activity. Over 300 Hazardous Early onset of certain diseases in addition to significant aggravation of symptoms and Elderly and persons with existing diseases should stay indoors and avoid physical exertion. Health Effects of Nitrogen Oxides • Short-term exposure at concentrations greater than 3 parts per million (ppm) can measurably decrease lung function. • Concentrations less than 3 ppm can irritate lungs. • Concentrations as low as 0.1 ppm cause lung irritation and measurable decreases in lung function in asthmatics. • Long-term lower level exposures can destroy lung tissue, leading to emphysema. • Children may also be especially sensitive to the effects of nitrogen oxides. Other Effects • Seriously injure vegetation at certain concentrations. Effects include: – Bleaching or killing plant tissue. – Causing leaves to fall. – Reducing growth rate. • Deteriorate fabrics and fade dyes. • Corrode metals (due to nitrate salts formed from nitrogen oxides). • Reduce visibility. Other Effects (Continued) • Oxides of nitrogen, in the presence of sunlight, can also react with hydrocarbons, forming photochemical oxidants or smog. • Also, NOx is a precursor to acidic precipitation, which may affect both terrestrial and aquatic ecosystems. Sulfur Dioxide Ninety-five percent of pollution related sulfur oxide emissions are in the form of sulfur dioxide (SO2), a heavy, colorless gas with an odor like a struck match. This gas combines easily with water vapor, forming aerosols of sulfurous acid (H2SO3), a colorless, mildly corrosive liquid. This liquid may then combine with oxygen in the air, forming the even more irritating and corrosive sulfuric acid (H2SO4). Other sulfur-containing compounds • Hydrogen sulfide (H2S) gas - rotten eggs. • Mercaptans - skunk spray or decayed garbage. (Added in trace amounts to natural gas, providing a leakdetecting warning odor.) Note: The amount of SO2 released from coal fired power plants depends on the sulfur content of coal, normally 0.7% to 2% by weight. High sulfur coal sometimes contains as much as 6% sulfur by weight. In India, sulfur content is quite low. Health Effects of Sulfur Oxides • Sulfur dioxide not only has a bad odor, it can irritate the respiratory system. • Exposure to high concentrations for short periods of time can constrict the bronchi and increase mucous flow, making breathing difficult. • Children, the elderly, those with chronic lung disease, and asthmatics are especially susceptible to these effects. Sulfur dioxide can also: • Immediately irritate the lung and throat at concentrations greater than 6 parts per million (ppm) in many people. • Impair the respiratory system's defenses against foreign particles and bacteria, when exposed to concentrations less than 6 ppm for longer time periods. • Apparently enhance the harmful effects of ozone. (Combinations of the two gases at concentrations occasionally found in the ambient air appear to increase airway resistance to breathing.) • Sulfur dioxide tends to have more toxic effects when acidic pollutants, liquid or solid aerosols, and particulates are also present. (In the past, thousands of excess deaths occurred in areas where SO2 concentrations exceeded 1 ppm for a few days and other pollutants were also high.) Effects are more pronounced among mouth breathers, e.g., people who are exercising or who have head colds. These effects include: • Health problems, such as episodes of bronchitis requiring hospitalization associated with lower-level acid concentrations. • Self-reported respiratory conditions, such as chronic cough and difficult breathing, associated with acid aerosol concentrations. (Asthmatic individuals are especially susceptible to these effects. The elderly and those with chronic respiratory conditions may also be affected at lower concentrations than the general population.) • Increased respiratory tract infections, associated with longer term, lower-level exposures to SO2 and acid aerosols. • Subjective symptoms, such as headaches and nausea, in the absence of pathological abnormalities, due to long-term exposure. Sulfur oxides Effects on Plants • Sulfur dioxide easily injures many plant species and varieties, both native and cultivated. Some of the most sensitive plants include various commercially valuable pines, legumes, red and black oaks, white ash, alfalfa and blackberry. The effects include: • Visible injury to the most sensitive plants at exposures as low as 0.12 ppm for 8 hours. • Visible injury to many other plant types of intermediate sensitivity at exposures of 0.30 ppm for 8 hours. • Positive benefits from low levels, in a very few species growing on sulfur deficient soils. Other Effects • Increases in sulfur dioxide concentrations accelerate the corrosion of metals, probably through the formation of acids. (SO2 is a major precursor to acidic deposition.) Sulfur oxides may also damage stone and masonry, paint, various fibers, paper, leather, and electrical components. • Increased SO2 also contributes to impaired visibility. Particulate sulfate, much of which is derived from sulfur dioxide emissions, is a major component of the complex total suspended particulate mixture. Health Effects of Ozone • Ozone acts as a powerful respiratory irritant at the levels frequently found in most of the nation's urban areas during summer months. • Ozone exposure may lead to: – Shortness of breath. – Chest pain when inhaling deeply. – Wheezing and coughing. Long-term, repeated exposure to high levels of ozone may lead to large reductions in lung function, inflammation of the lung lining, and increased respiratory discomfort.