Sunday, July 14, 2013

Sumatra haze becoming a yearly recurring event with growing pollution level?

Figure 1 : On Saturday, June 22, 2013, motorists make their way through a town covered with a thick haze in Muar. FILE PHOTO: AP

In South Peninsular Malaysia and Singapore island, the last Sumatra’s smoke haze spell – 23 days from 10 June to 2 July 2013- was definitely more serious than the last year occurrence, while haze’s pollution could still return anytime during the coming months.  

A huge amount of information was published by various media during this period. But sometimes the true meaning of air pollution information issued and their outcome in terms of public health were difficult to understand and - to say it bluntly- a little hazy!

We would like to return on this period and look at all data issued on air quality by Department of Environment (DOE) in Malaysia, National Environment Agency (EPA) in Singapore and ASEAN Specialised Meteorological Centre (ASMC).

How are established both Air Pollution Index (API) in Malaysia and Pollutant Standards Index (PSI) in Singapore?

All figures concerning air pollution index and sub-indices in Malaysia or Singapore are established following rules very similar to the US Air Quality Index  (see AQI Technical Assistance document for the Reporting of the Air Quality Index AQI).

For the US AQI, first specific sub-indexes are separately computed concerning the 6 following pollutants:

(1)- Particulate matter smaller than 10µm (PM10 ),

(1bis)- Particulate matter smaller than 2.5µm (PM2.5),

(2)- Ozone (O3),

(3)- Carbon monoxide (CO),

(4)- Sulfur dioxide (SO2) ,

(5)- Nitrogen dioxide (NO2) .

For each pollutant a common “grid” of communication relationship is introduced, with a growing scale grid and associated pollution level where: 0-50 is a “good air quality”, 51-100  is a pollution “moderate”, 101-150 a pollution  “unhealthy for specific groups”, 151-200  is a pollution ”Unhealthy”, 201-300  is “very unhealthy”, and 301-500 is “Hazardous”.

Then each sub-index is computed and the highest sub-index value is the US AQI value for the location and the time concerned.

The only difference concerning Malaysia’s API and Singapore’s PSI in relation with US AQI is the PM2.5 pollutant. 

In fact (1)) and (1bis) pollutants are closely interrelated because particulate matter smaller than 2.5µm are also smaller than 10µm. However PM2.5 are also much more unhealthy and as such should have a higher “grid” value!

In the case of Malaysia, PM2.5 seems to be measured but is not published.

In the case of Singapore , PM2.5 is measured and published with the PSI index.

API & PSI values are computed based on the average concentrations of air pollutants PM10, O3, CO, SO2 and NO2 expressed in µg/m3 or in ppm. The average time period is pollutant specific: daily for PM, 8h for CO, hourly O3, SO2 and  NO2.  

During the haze spell in Malaysia the PM10 sub-index value due to the high PM10 concentration is the highest compared with the other pollutants and this determines the API readings.

Nevertheless by the late afternoon or early evening, usually ozone concentration is high and dominates the API readings in some areas. Under the sunlight influence, nitrogen dioxide and volatile organic compounds emitted from motor vehicle exhaust and industry react to form ozone in the earth's surface.    

Peninsular Malaysia was more severely affected than Singapore

In both countries the monitored pollutants and sub-indexes are the same and so the comparison is meaningful. 

The following Figures 2 & 3 give the API readings in Malaysia:

Figure 2 : API index from 22 June to 2 July 2013 on 11 locations in Johor, Malaka, N. Sembilan and South Pahang  (see DOE Malaysia)

Johor (Kota Tinggi, Larkin Lama, Muar, Pasir Gudang ), Melaka (Bandaraya, Bukit Rambai) and Negeri Sembilan (Port Dickson)  were especially polluted with the highest API reading  ever seen in Johor Muar (756 API on 23 June), as explained my Malaysian Environment Minister in Asia Pacific Channel News.

Figure 3 : API index reading on 13 locations in Perak, Selangor, Kuala Lumpur  and Terengganu (see DOE Malaysia)

Selangor (Banting , Pelabuhan Kelang) and  Terengganu (Kemaman) were especially polluted with the highest reading in Selangor Pelabuhan Kelang (487  API on 27 June).

The Figure 4 gives the PSI reading in Singapore:

Figure 4 : PSI readings on 5 locations in Singapore (see NEA Singapore

Generally speaking, Singapore was less polluted than Malaysia: around 5500 cumulated readings unhealthy for special group on 23 days (at 7am, 12am, 4pm) compared to 7500 cumulated reading in Malaysia during the same period (7am, 11am, 5pm).  

South Singapore was especially polluted, with the reading (PSI=246 on 22 June). The highest points in Peninsular Malaysia being 400-700.

So if we take off the "good readings" and look also at the highest readings, Malaysia was at least "twice more polluted" than Singapore during this haze spell.

Moreover the 2013 haze spell (in June and up to 15 July) was much more severe than 2012 June and July occurrence,  but with a hotspot count very similar

Compared to the 2012 June & July haze in Malaysia: the spell is much stronger and only located on South peninsular Malaysia .

In 2012 there was a 4000 cumulated reading (at 7am, 11am, 5am) and the maximum readings were in Sarawak (API=247 on 27 June 2012), Selangor  (API=147 on 15 June 2012), with Penang having a 5 day haze spell (API=105 on 20 June 2012).

In 2012, the cumulative hotspot count for Sumatra while being among the 2 highest of the last 8 years is in line with last year count progression (see following Figures 5, 6 & 7).  

So the haze in becoming more or less a yearly recurring hazard with pollution growing each year!

Figure 5 : Cumulative hotspot count for Sumatra detected in the ASEAN region for 2006 to 30th June 2013; the counts are based on the hotspots detected by the NOAA-18 Satellite

In Sumatra  the open burning areas seemed to be more located over the Riau Province  in Central Sumatra,  while last year the hot spots were coming up to Kualuh Hilir in North Sumatra.  

This combined by the direction of winds have kept the Northern states of Perak and Pulau Penang  less affected.

The international uproar have been so severe – especially from Singapore- that the Indonesian Government had announced its decision to ratify the“2002 Asean Treaty on Transboundary Haze Pollution signed by all 9 other ASEAN countries.  

Figure 6 : Regional haze map on 21 June 2013 

Figure 7 : Regional haze map on 23 June 2013