Wednesday, August 06, 2008

Air Pollution Analysis - Models vs. Methodology

For air pollution analysis, irrespective of the models that exist, their advantages and disadvantages, their availability or their ease to execute, the problem has always been the “methodology”. If a calculator was provided, people would jump on it to put some numbers and come up with an answer, especially, when the credibility of the modeling numbers is at risk.

Any of the models in common use, such as HEAT by ICLEI, or MOVES, or COPERT, or Air-QUIS by NILU, have been around for years and a number of countries or cities (in Americas, Europe, Asia, or Africa) have applied them to their fullest extent (not included here some specialized models for emissions, dispersion, or impact assessments). Most in the decision making process at local, national, and international level, at some level, are familiar with one or all of these models and given the right data, these models will provide an immense pool of knowledge and a commendable tool for customization with local needs. The key word, however, is “data”.

There is need for a clear distinction required between the "models" and "methodology". A "methodology" could mean a fundamental equation, focusing on "what is essential" to arrive at a decision, while a "model" will focus on "what is needed" to arrive at a decision. A varying a degree of requirements !!

For example, Bus Rapid Transport (BRT) exercise - 17 cities have BRT and 33+ are preparing for one. I haven’t seen any analysis of all the projects, but I am sure the agencies and bureaus involved in the construction did a thorough scrutiny of the current traffic patterns and what changes will work best. If we dig a little deeper, this was possible because the projects, Bogota (a good example) aside, teams spent some "time" monitoring the patterns, preparing the feasibility studies, etc. Now, of the 50 cities, if all were invited to one place and asked to present the BRT analysis, all them will present and probably do a good job doing it. If the same cities were asked, how many have prepared a vehicular emissions inventory for the city, probably very few will answer?

What I see is the existence of a "methodology" (BRT) to follow and do the necessary calculations.

I don’t want to single out the transport sector in this context. Same goes with the industrial methodologies and pollution control options - as simple as the CFL light bulbs. At the lowest level, the campaigns and public awareness make a lot of difference in making the necessary switch from the regular candescent bulb to CFL. CFLs existed in the market for a long time, at a higher price however. Only with demonstrations and examples that the switch was possible and show that on a long run, people will save money. The initial investment was higher than the regular, but people understand the difference now. I am not economist, but demand-supply curve plays a role, with growing demand and higher productions, the supply increased (more manufacturers entered the market) and the CFL rates are lower than what they used to be.

Again, the math was made simple between what you pay for the electricity based on your usage and what you get out of the new system. Sometimes, for a household - though the environmental and social (intangible) benefits outweigh the monetary savings (tangible), the decision making is difficult, because there isn't a set methodology to follow, except for comparison of an old and new model (bulb). However, an example and simple methodology will help the decision making easy – whether it is changing a bulb or a BRT for a 10 km road.

When dealing with air pollution, given the number of sources ranging from household (including garbage burning) to transport, what cities need is an emission inventory to compare the baselines and the benefits of the interventions (albeit at the city level). Access to data means better knowledge base, improved management decisions, and a healthy environment (said and discussed many a times). We have hundreds of models and ton of experience – big and small – complex and simple - I think what needs to be presented is a methodology – a fill in the blanks exercise for cities to follow.

Of course, at the end of the day, the reliability of the data is a problem and always questionable - even if it is number of vehicles on the road (from the registrations) or the vehicle kilometers traveled by a single vehicle. But, we have to start some where to get the cities organized. Similarly, the industries or domestic sector – there is no single answer for amount of coal or oil consumed in a month or a year. Technically speaking all the pollution control boards should know the current levels and have some back of the envelope calculations – then we also face the problems of information sharing and coordination between departments.

Most of the times, the modeling of emissions, concentrations, scenarios, and analysis, has been limited to the academic world (at least in the details). For every city, there is at least one university or one professor or one student, who is conducting some level of research towards estimating pollutants and modeling – question of how credible or reliable the data, is secondary. Modeling has never been easy !!

Among the frequently asked questions or comments that top the chart are
  1. Emission factors need to be city specific - can’t and shouldn’t argue with that. Now, if there is a city which doesn’t have any resources or haven’t ever done an emission testing, should they wait for a year or more before they develop an emission inventory?
  2. Data collection is hard and the models require a lot of data - can’t argue with that either. All our models are data hungry. Even the SIM-air, as simple as I claim it to be, still needs some level of input from the participants. And even that is hard to get. Invariably the question of reliability comes in – which is a good, because we need to know the uncertainties in the data before we crunch the number. Not that the data collection is hard, I believe it’s the data sharing that hard. Main reason being the segregated departments – energy, transport, environment, and urban.
  3. Resources (personnel and financial) are limited and timing is everything - putting together information in a coherent manner is a time consuming effort and making the necessary analysis in a timely fashion is key to a good decision making process. For the decision makers, if there is a nice button driven tool available and as long as it doesn’t ask many questions, it’s the best. But how often is it true or easy?
Some efforts are required (and necessary) in building more interactive "methodologies" and use the existing "models" as guidelines to make the necessary analysis. At some level, we know what works and what doesn’t. It’s a matter of putting down steps to develop a methodology that cities can (and will) follow.

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