An emergency plan called the Graded Response Action Plan has been notified by the Ministry of Environment, Forest & Climate Change for implementation under different Air Quality Index (AQI) categories.

The different AQI categories are Severe, Very poor and Moderate & Poor. The cut-off levels of PM2.5 or PM10 have been defined for each category as have been the actions to be implemented and the agency responsible for implementing the specified actions.

The actions to be implemented under the Severe or Emergency category defined as “ambient PM 2.5 or PM 10 concentration values of 300μg/m3 or 500 μg/m3 respectively persist for 48 hours or more” are:

1. Stop entry of truck traffic into Delhi (except essential commodities)
2. Stop construction activities
3. Introduce odd and even scheme for private vehicles based on license plate numbers and minimize exemptions
4. Task Force to take decision on any additional steps including shutting of schools

The graded response action plan, as the name suggests, also lists action to be taken under different categories such as severe, very poor and moderate to poor (defined as below).

1. Severe (ambient PM2.5or PM10 concentration value is more than 250 μg/m3or 430μg/m3 respectively)
2. Very poor (ambient PM2.5or PM10 concentration value is between 121-250μg/m3or 351-430 μg/m3 respectively)
3. Moderate to poor (ambient PM2.5 or PM10 concentration value is between 61-120 μg/m3 or 101-350 μg/m3 respectively)

What stands out in this Action Plan is the time period of 48 hours specified only for the Severe or Emergency category, but not for other categories.

The question here is why this time period of 48 hours?

One cannot wait for 48 hours to declare an emergency. If AQI remains high in the severe or emergency category, even for a very short period of time, a person will have suffered the ill-effects. They will not wait for 48 hours to set in.

AQI in the severe category not only affects those with underlying heart or lung disease, but also those who are healthy.

Breathing polluted air for even two hours can increase blood pressure, potentially raising the risk of cardiovascular disease in those exposed to smog. In susceptible patients, this small increase may actually be able to trigger a heart attack or stroke.  . 

Short-term exposure to air pollutants (both ozone and fine particulate matter) has been associated with total mortality¹ and acute coronary ischemic events^2-5

1. In a case-crossover study of more than 22 million deaths between 2000 and 2012 identified from the United States Medicare population, increased risk of all-cause mortality was seen with short-term increases in fine particulate matter (RR increase 1.05 percent for each 10 mcg/m3 increase) and ozone (RR increase 0.51 percent for each 10 part per billion increase). ¹ The increased risk occurred at levels of air pollution that are lower than the currently suggested air quality standards.
2. In a study of over 12,000 patients living in a defined geographic area, a short-term increase in fine ambient particulate matter positively correlated with an increase in acute ischemic coronary events. ²
3. In a systematic review and meta-analysis of data from 34 studies, carbon monoxide, nitrogen dioxide, sulfur dioxide, and small particulate matter (less than 10 microns and less than 2.5 microns) were all associated with an increased risk of myocardial infarction (MI), with the overall population attributable risk ranging from 1 to 5 percent. ⁶

Possible mechanisms by which fine particulate air pollution may increase the risk of CVD include:⁷

1. An increase in mean resting arterial blood pressure through an increase in sympathetic tone and/or the modulation of basal systemic vascular tone⁸
2. An increase in the likelihood of intravascular thrombosis through transient increases in plasma viscosity and impaired endothelial dysfunction⁹
3. The initiation and promotion of atherosclerosis^10,11

When the AQI reaches the level, high enough to be categorized as emergency, the pre-emptive measures should start automatically by the concerned agency including us, as individuals.

For instance, if the AQI is in the emergency category, schools/colleges should stop all outdoor activities including sports and the school medical officer should advise closing of the school.

1. The odd and even scheme can be self-implemented in such a situation.
2. Walk or cycle for short distance commutes or to the neighborhood market. Plan and combine all your errands in one area or close by areas for one trip. Limit driving and make use of carpool.
3. Use public transport as much as possible for longer distances. If you have to use your vehicle keep it well maintained for efficient functioning with regular servicing to reduce harmful exhaust emissions and get pollution check done as required. Follow speed limits. Avoid buying diesel vehicle.
4. Avoid burning candles dhoop or incense sticks at home or workplace.
5. Wet mop the floors at home or workplace

The AQI varies from area to area. It may be higher in some parts of Delhi, for example; at places, it may be lower. Hourly AQIs can be obtained for different areas of Delhi at http://www.dpccairdata.com/.

Each of one of us should act, instead of waiting for the government to enforce the graded action plan after a period of 48 hours.

Check the daily pollution levels in your area and be proactive in taking precautions.

Self-regulation is the answer…

References

1. Di Q, Dai L, Wang Y, et al. Association of short-term exposure to air pollution with mortality in older adults. JAMA 2017;318:2446.
2. Pope CA 3rd, et al. Ischemic heart disease events triggered by short-term exposure to fine particulate air pollution. Circulation 2006;114:2443.
3. Ruidavets JB, Cournot M, Cassadou S, et al. Ozone air pollution is associated with acute myocardial infarction. Circulation 2005; 111:563.
4. Tonne C, Wilkinson P. Long-term exposure to air pollution is associated with survival following acute coronary syndrome. Eur Heart J 2013;34:1306.
5. Sinharay R, Gong J, Barratt B, et al. Respiratory and cardiovascular responses to walking down a traffic-polluted road compared with walking in a traffic-free area in participants aged 60 years and older with chronic lung or heart disease and age-matched healthy controls: a randomised, crossover study. Lancet 2018;391:339.
6. Mustafic H, Jabre P, Caussin C, et al. Main air pollutants and myocardial infarction: a systematic review and meta-analysis. JAMA 2012;307:713.
7. Newby DE, Mannucci PM, Tell GS, et al. Expert position paper on air pollution and cardiovascular disease. Eur Heart J 2015;36:83.
8. Brook RD, Brook JR, Urch B, et al. Inhalation of fine particulate air pollution and ozone causes acute arterial vasoconstriction in healthy adults. Circulation 2002;105:1534.
9. Pekkanen J, Peters A, Hoek G, et al. Particulate air pollution and risk of ST-segment depression during repeated submaximal exercise tests among subjects with coronary heart disease: the Exposure and Risk Assessment for Fine and Ultrafine Particles in Ambient Air (ULTRA) study. Circulation 2002;106:933.
10. Sun Q, Hong X, Wold LE. Cardiovascular effects of ambient particulate air pollution exposure. Circulation 2010; 121:2755.
11. Bauer M, Moebus S, Möhlenkamp S, et al. Urban particulate matter air pollution is associated with subclinical atherosclerosis: results from the HNR (Heinz Nixdorf Recall) study. J Am Coll Cardiol 2010;56:1803.