Potential Impact of Biomass Burning on Urban Air Quality: Case-study of Chiang Mai

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1 Potential Impact of Biomass Burning on Urban Air Quality: Case-study of Chiang Mai Sébastien Bonnet, Narongchai Suwanprik and Savitri Garivait The Joint Graduate School of Energy and Environment

2 Chiang Mai Chiang Mai is the second largest city in Thailand with an area of 2,17 km 2. Its population amounts to 1.6 millions inhabitants. Chiang Mai is situated at 31 meters above sea level and is surrounded by hills covered with trees (forest type of vegetation). Due to the topographical characteristic of Chiang Mai, air pollution is a major issue in particular during the dry period (Jan. - Apr.) when pollutants like PM1 reach a concentration that largely exceed the Ambient Air Quality Standard of 12 µg/m 3 (24 hr. av. conc.)

3 Land use of Chiang Mai and surrounding area

4 Objectives of this Study Evaluate potential contribution of biomass burning on air pollution in the city Investigate the impacts of biomass open burning on the Chiang Mai s air quality

5 Materials and Methods Two monitoring stations in Chiang Mai: Urban site: 36TM Sub-urban site: 35TM Continuous monitoring of specific air pollutants on an hourly basis i.e. CO, O 3, CH 4, NOx (NO + NO 2 ), PM1 plus others i.e. NMHC and THC Some meteorological parameters are also monitored such as: rain, wind direction, wind speed, pressure, etc.

6 Monitoring sites Site 35 6 km Site 36

7 Sub-urban Site: Primary and Secondary Air Pollutant Concentration Monthly Average PM1, NOx, O CO Jan-2 Feb-2 Mar-2 Apr-2 May-2 Jun-2 Jul-2 Aug-2 Sep-2 Oct-2 Nov-2 Dec-2 Time O3 (ppb) PM1 (ppm) NOx (ppb) CO (ppm

8 Urban Site: Primary and Secondary Air Pollutant Concentration Monthly Average PM1, NOx, O CO Jan-2 Feb-2 Mar-2 Apr-2 May-2 Jun-2 Jul-2 Aug-2 Sep-2 Oct-2 Nov-2 Dec-2 Time O3 (ppb) PM1 (ppm) NOx (ppb) CO (ppm)

9 Sub-urban Site: Diurnal Characteristics in February NOx, NO, NO2 and O3 (ppb) CO (ppm) Time (hours) NO NO2 NOx O3 CO.4

10 Urban Site: Diurnal Characteristics in February NOx, NO, NO2 and O3 (ppb) CO (ppm) Time (hours) NO NO2 NOx O3 CO

11 Pollutants concentrations distribution There is considerable seasonal variability in pollutant concentrations The monthly average plots show that the concentrations of both primary and secondary pollutants tend to peak in the November through March time It is also apparent that the urban site with the highest NOx has the lowest O 3 while the suburban site with the lowest NOx as the highest O 3 (typical diurnal characteristics)

12 Scatter Plots between concentration of CO and NOx (22) 2 36TM22_CO-NOx.1YrHrAv TM22_CO-NOx.1YrHrAv NOx (ppb) 1 NOx (ppb) CO (ppm) CO (ppm) Urban Site Sub-urban Site

13 Scatter Plots between concentration of CO and PM1 (22) TM22_CO-PM1.1YrHrAv TM22_CO-PM1.1YrHrAv PM1 (microg/m3) 3 2 PM1 (mcrog/m3) CO (ppm) CO (ppm) Urban Site Sub-urban Site

14 Data on rainfall from meteorological station in Chiang Mai (22) Month Rainfall (mm) Wind speed (m/s) January February March April May June July August September October November December

15 Wind Characteristics January-March and October-December: Wind direction: NNW to SE Calm wind conditions: (.8 to 1.2 m/s) Little dispersion of air pollutants (poor air quality observed) Low rainfall (no wet deposition) Peak season of forest fires and paddy fields burning activities

16 Biomass burning in Chiang Mai Area of vegetation burned (22) 1,2 1, Area burned (km 2 ) 1, Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Area burned (km 2 ) Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Month Forest Paddy fields

17 Conclusion PM emission sources contribution in Chiang Mai city pollutants Types of sources Total Point source Mobile source Area source Tons/year PM.59 (.1) 18.1 (2.6) (97.3) (1) Chiang Mai Municipality Report, 24

18 Conclusion CO and NOx of traffic origin PM1 originates from area sources High PM emission during the dry season period of vegetation fires Forest vegetation on the west side of the city Biomass burning forest fires - likely contributor of PM 1 pollution in particular during the dry season.

19 Thank you for your attention!