1. Mohd Talib Latif

2. Introduction An air quality standard is a description of a level of air quality that is adopted by a regulatory authority as enforceable. The basis of development of standard should be to provide a rational for protecting public health from adverse effects of air pollutants, to eliminate or reduce exposure to hazardous air pollutants, and to guide national and local authorities in their air quality management decisions.

3. Step to Develop Standard The first step included compilation of air quality standards adopted by various countries including guidelines suggested by the WHO. The second step was to summarize the problems and issues associated with Hazardous Air Pollutants (HAPs). The USEPA has identified 188 HAPs (for details see: http://www.epa.gov/ttn/atw/allabout.html

4. Averaging Time The basis for averaging time is from the fact that large peak concentrations can damage the health even during exposure of short time. For example, CO, NO x, SO 2 and O 3 have short-term effects and have been assigned 1-hr averaging time in addition to 24-hr and annual averages. It was decided that even if a contaminant does not have any short-term effect, a standard of 24-hr averaging time must be assigned so that trend of possibility of long-term concentration can be determined and suitable corrective measures are not delayed.

5. Criteria of Standard whether substances or mixtures posed a widespread problem in terms of sources; the ubiquity and abundance of the pollutants where the potential for exposure was large; whether significant new information on health effects was available; the feasibility of monitoring; and past trend in ambient air levels

7. http://www.epa.gov/air/criteria.html

8. Primary StandardsSecondary Standards PollutantLevelAveraging TimeLevelAveraging Time Carbon Monoxide 9 ppm (10 mg/m 3 ) 8-hour (1) (1) None 35 ppm (40 mg/m 3 ) 1-hour (1) (1) Lead0.15 µg/m 3 (2) (2) Rolling 3-Month Average Same as Primary 1.5 µg/m 3 Quarterly Average Same as Primary Nitrogen Dioxide 0.053 ppm (100 µg/m 3 ) Annual (Arithmetic Mean) Same as Primary Particulate Matter (PM 10 ) 150 µg/m 3 24-hour (3) (3) Same as Primary Particulate Matter (PM 2.5 ) 15.0 µg/m 3 Annual (4) (Arithmetic Mean) (4) Same as Primary 35 µg/m 3 24-hour (5) (5) Same as Primary Ozone0.075 ppm (2008 std) 8-hour (6) (6) Same as Primary 0.08 ppm (1997 std)8-hour (7) (7) Same as Primary 0.12 ppm1-hour (8) (8) Same as Primary Sulfur Dioxide 0.03 ppmAnnual (Arithmetic Mean) 0.5 ppm (1300 µg/m 3 ) 3-hour (1) (1) 0.14 ppm24-hour (1) (1) National Ambient Air Quality Standards

9. The Air Quality Standards Regulations 2007 Air Quality Guideline for Europe http://ec.europa.eu/environment/air/quality/standards.htm

10. PollutantConcentrationAveraging periodLegal naturePermitted exceedences each year Fine articles (PM2.5)25 µg/m3***1 yearTarget value enters into force 1.1.2010 Limit value enters into force 1.1.2015 n/a Sulphur dioxide (SO2)350 µg/m31 hourLimit value enters into force 1.1.2005 24 125 µg/m324 hoursLimit value enters into force 1.1.2005 3 Nitrogen dioxide (NO2) 200 µg/m31 hourLimit value enters into force 1.1.2010 18 40 µg/m31 yearLimit value enters into force 1.1.2010* n/a PM1050 µg/m324 hoursLimit value enters into force 1.1.2005** 35 40 µg/m31 yearLimit value enters into force 1.1.2005** n/a

11. Lead (Pb)0.5 µg/m31 yearLimit value enters into force 1.1.2005 (or 1.1.2010 in the immediate vicinity of specific, notified industrial sources; and a 1.0 µg/m3 limit value applies from 1.1.2005 to 31.12.2009) n/a Carbon monoxide (CO) 10 mg/m3Maximum daily 8 hour mean Limit value enters into force 1.1.2005 n/a Benzene5 µg/m31 yearLimit value enters into force 1.1.2010** n/a Ozone120 µg/m3Maximum daily 8 hour mean Target value enters into force 1.1.2010 25 days averaged over 3 years Arsenic (As)6 ng/m31 yearTarget value enters into force 1.1.2012 n/a Cadmium (Cd)5 ng/m31 yearTarget value enters into force 1.1.2012 n/a Nickel (Ni)20 ng/m31 yearTarget value enters into force 1.1.2012 n/a Polycyclic Aromatic Hydrocarbons 1 ng/m3 (expressed as concentration of Benzo(a)pyrene) 1 yearTarget value enters into force 1.1.2012 n/a

12. United Kingdom National Air Quality Strategy - Air Quality Objectives Benzene- 5ppb measured as running annual mean (31/12/2003) 1,3-Butadiene- 1ppb measured as running annual mean (31/12/2003) *Nitrogen Dioxide (i)- 105ppb not to be exceeded more than 18 times a year measured as 1 hour mean (31/12/2005) *Nitrogen Dioxide (ii)- 21ppb measured as annual mean (31/12/2005) PM10 Particles (i)- 50 µg/m 3 not to be exceeded more than 35 times a year measured as 24 hour mean (31/12/2004) PM10 Particles (ii)- 40 µg/m 3 measured as annual mean (31/12/2004) Sulphur Dioxide (i)- 132ppb not to be exceeded more than 24 times a year measured as 1 hour mean (31/12/2004) Sulphur Dioxide (ii)- 47ppb not to be exceeded more than 3 times A year measured as 24 hour mean (31/12/2004) Sulphur Dioxide (iii)- 100ppb not to be exceeded more than 35 times a year measured as 15 minute mean (31/12/2005) Carbon Monoxide- 10ppm measured as running 8 hour mean (31/12/2003) **Ozone- 50ppb not to be exceeded more than 10 times a year measured as the daily max of running 8 hour mean (31/12/2005)

14. Change to the unit of mass/volume (ug/m 3 ) involve the I Ideal Gas Law PV = nRT P = Pressure (mm Hg) T = Temperature (K) R = Ideal gas constant

15. Change of unit

16. R = 8.314472JJ·mol −1 ·K −1molK = 8.314472 m 3 ·Pa·K −1 ·mol −1 = 8.314472 kPa·L·mol -1 ·K - 1 = 0.08205746 LL·atm·K −1 ·mol −1atm = 62.36367 L·mmHg·K −1 · mol −1mmHg = 10.73159 ft ft 3 ·psi·°R −1 ·lb- mol −1psi°Rlb- mol = 53.34 ftft·lbf·°R −1 ·lbm −1 (for air)lbf°Rlbm

17. Changing Averaging Time Formula [C1 /C2] = [t 2 /t 1 ] p C1 = Concentration 1 C2 = Concentration 2 t1 = time 1 t2 = time 2 0.17 < p < 0.50 (Turner, 1970; Engel et al. 1997; Scire et al., 2000)