Is Revising the Air Pollution Standards Enough?

India revised its NAAQS standards in the year 2009 after a gap of 15 years. The 24-hour standard for PM2.5 under the NAAQS is 60 whereas it is 25 as per WHO guidelines 2005. WHO has just revised its 2005 standards in 2021 – PM 2.5 has been kept at 15µg/m3. The PM10 standard is 100 µg/m3 (NAAQS) and 50 µg/m3 (WHO, 2005) and now revised to 45 µg/m3 (WHO, 2021). Is it enough to revise the standards, does our past reflects upon the strategies that have worked or require rethinking. Environics has installed portable devices to monitor air quality in the following locations and a look at these data sets obtained for the last 15 months show the State of Environment and compliance with air pollution standards to say the least.

Note: Figures in parenthesis indicate number of monitoring locations

Korba has the largest number of days monitored as the number of monitoring locations are 13 followed by New Delhi (9) and Sambalpur (2). More details can be seen in the table below where percentage of exceedance occasions is shown against the norms. Almost 10-21% of the PM2.5 values remain in the 46-60 µg/m3 category which is the immediate borderline of NAAQS norm. If we look at the range 0-15 i.e. under 15 µg/m3 Kolkata leads with 23% values within the WHO 2021 norms and Asansol represent the least at 0.25%. Kolkata has 41.41% occasions when values fall within the WHO 2005 standard of 25 µg/m3 (18% detereoration over 2005 norm) whereas the detereoration for Asansol is 1.75%. More can be seen in annexure I
Table 2 – Percentage of occasions when PM2.5 values exceeded the WHO and NAAQS norms (Location wise exceeding norms only)

All locations showed high percentage exceedance for 24 hr PM2.5 for WHO standards for the pollutant. Asansol has none of the values under the WHO norms. On 70% occasions Asansol’s PM2.5 values exceed the NAAQS norms. All other locations except Raigarh show exceedance occasions in the percentage range of 31-45%, Korba with 45% and Kolkata with 31%. More than 1/3^rd of the occasions PM2.5 remains above the national norm for 24 hourly average concentration of the pollutant.

Almost 10-16% of the PM10 value remains in the 81-100 µg/m3 range for all the locations which is bordering the 100 µg/m3 norm (NAAQS). Kolkata again leads with 1/3^rd of its PM10 values within the WHO 2021 guidelines for PM10 whereas it deteriorates with 7 percentage points if compared to 2005 guidelines. Asansol again shows deterioration by loosing almost 2.21% percentage points to 2021 guidelines. More details can be seen in Annexure I

Table 4 – Percentage of occasions when PM10 values exceeded the WHO and NAAQS norms (Location wise exceeding norms only)

Unlike PM2.5, PM10 percentage exceedance occasions show variability in the 2005 and 2021 standards for the pollutant. Asansol shows the least variation and high values among all locations indicating PM10 values are rarely under 50. Korba and Sambalpur are also in the high range of 93 and 90 respectively. Raigarh indicates the mid-point where the exceedance is 84% just succeeding New Delhi. Some variability is seen in Kolkata and Raigarh viz. 7 and 10 percentage points. The NAAQS standard is also breached in all the locations with exceedance occasions being the maximum in Asansol (76%) followed by Korba, New Delhi. Jharsuguda, Sambalpur and Kolkata in the eastern region are in the exceedance range of 33-38%. This asks for improvement in air environment and strict regulation rather than adjusting the standards alone.

SEASONAL RESULTS, 2020

Clear correlation is seen in more safe occasions of PM2.5 during the pre-monsoon and during monsoon period lasting for almost six months. Kolkata shows the maximum compliance with the WHO 2005 standard during pre-monsoon (90%) as well as during monsoon (88%) – least variation among these two periods.

Delhi too has least variations but the compliance level is 34-36% occurrences in the safe limit (WHO 2005). Korba goes further down with 15-18%, Raigarh at 25%. Sambalpur as well as Jharsuguda show large variations from April-June to July September period i.e. 4-16% and 17-45% respectively as far as compliance to 2005 standards is concerned over these two periods. Ony 4% safe occurrences occur for Asansol during the monsoon period thereby indicating high background emissions all round the year. One must remember that Raniganj coalfields have several fire occurrences which may contribute to the background emissions as far as PM2.5 and PM10 is concerned.

Winter months are the worst where very fewer safe occurrences happen over few locations. In these months too, Kolkata leads the table but unlike pre-monsoon and monsoon period, there is considerable drop in safe values w.r.t. WHO 2005 standard for PM2.5.

Even when compared to the national NAAQS standard for 24 hour averaged PM2.5, it exceeds the limit of 60 in all locations, some even showing 100% of the occurrences above the safe limit prescribed in the 2009 norms – Asansol, Jharsuguda fall in this category for the winter months. Delhi in the October – December period has 89% occurrences above the safe limit, Korba 67%.

The purpose of devising pollution standards is to mobilise the regulatory mechanism to curb pollution, introduce technological improvements which are like investing in public health at large. The CPCB initiated mapping and analysing critically polluted areas and brought out a Comprehensive Environment Pollution Index in the year 2010. But whether the situation improved over the last decade shows some reflection. If the amount invested to curb pollution is equated to the improvement gained in terms of lowering pollution, the story will be clear. But such data is not consolidated at one place. The technological improvements in terms of centralised monitoring of facility level stack emissions is appreciable, equally important is making the data public and devising improvement strategies.