Categorisation of Industries

India sorts its industries into colour groups based on how much pollution they can cause. The most polluting industries are placed in the Red category, then come Orange, Green and White (practically non-polluting). Since 2025, there is also a Blue category for essential waste-management services. The colour decides where an industry can be set up, how long its pollution permit lasts, and how often officials inspect it.

The lists are prepared by the Central Pollution Control Board (CPCB) and used by every State Pollution Control Board (SPCB).

Why is it needed?

Not all factories pollute equally. A cement plant or a chemical unit can harm air and water much more than a unit that assembles bicycles. If the government treated all of them the same, it would either over-burden clean industries with paperwork or be too soft on dirty ones. Colour coding works like a hospital triage system: the most serious cases get the most attention. Pollution boards can then spend their limited staff on the industries that matter most.

Where did it come from?

• The idea began with a 1989 notification for the Doon Valley (now in Uttarakhand), which sorted industries into red, orange and green to decide where they could be located.
• Other states later started using it for pollution permits too, but each state had its own list. In 2012, the CPCB issued one standard list of 244 sectors: red (85), orange (73) and green (86).
• On March 5, 2016, the Ministry of Environment, Forest and Climate Change released a new system based on a scientific Pollution Index (PI). It also added the White category for practically non-polluting industries, which do not need environmental clearance or a pollution consent. At launch, the list had 60 red, 83 orange, 63 green and 36 white sectors.
• On January 22, 2025, the CPCB published a revised report, "Classification of Sectors into Red, Orange, Green, White and Blue Categories", with a new method and the new Blue category.

How does the Pollution Index work?

Each industry sector gets a score out of 100 for each of three types of pollution:

1. Water pollution score: based on how dirty and how large the wastewater flow is.
2. Air pollution score: based on emissions from chimneys, dust and smells, and the type and amount of fuel burnt.
3. Hazardous waste score: based on the type and amount of toxic or dangerous waste.

These are combined into one Cumulative Pollution Index. Since 2025, all three are given equal weight.

The score ranges (2025 method)

• Red: PI of 80 or more
• Orange: PI from 55 to below 80
• Green: PI from 25 to below 55
• White: PI below 25

Under the older 2016 method, the cut-offs were lower: Red 60 and above, Orange 41 to 59, Green 21 to 40, and White up to 20. Exam questions may ask about either, so note the year.

The Blue category

This covers essential environmental services that manage waste from homes, such as facilities that handle domestic solid waste. One example is compressed biogas plants that process municipal solid waste or farm residue. Similar plants that process industrial waste stay in the Red category. Blue units are needed for a cleaner environment, so they are rewarded: their pollution permit is valid for 2 years longer than their PI category would normally allow.

How many sectors are in each category (2025)?

The 2025 report lists 419 sectors and sub-sectors:

• Red: 125
• Orange: 137
• Green: 94
• White: 54
• Blue: 9

How is the classification used?

• Consent management: Under the Water (Prevention and Control of Pollution) Act, 1974 and the Air (Prevention and Control of Pollution) Act, 1981, an industry needs a Consent to Establish (CTE) before building and a Consent to Operate (CTO) before running. A CTO can be valid for up to 5 years (Red), 10 years (Orange) and 15 years (Green). Consent rules for White units follow recent amendments to these laws, including the Jan Vishwas (Amendment of Provisions) Act, 2023.
• Inspections: SPCBs must inspect Red units at least once every six months, Orange units once a year, and Green units once every two years.
• Siting: The colour helps decide where a unit can come up. Under the CPCB's 2016 directions, no Red-category industry is normally allowed in ecologically fragile areas or protected areas.
• Environmental compensation: The PI can be used to set the fine on units that break pollution rules.
• Incentives: Units that adopt cleaner practices, such as treating and reusing 100% of their wastewater or using only clean fuel, can get benefits like longer permit validity.

India's use in eco-sensitive areas

Many Eco-Sensitive Zone and Ecologically Sensitive Area notifications directly use these colours. For example, the Western Ghats ESA drafts, based on the Kasturirangan Committee report, ban new red-category industries inside the ESA. This is why whether an area falls inside or outside the ESA matters so much for large industrial projects.

Commonly confused concepts

• Colour category vs EIA Category A/B: The colour system (Red, Orange, Green, White, Blue) is run by pollution boards for consents and inspections. Category A and B under the EIA Notification, 2006 decide who grants environmental clearance: Category A projects are cleared by the Centre, and Category B by state-level authorities (SEIAA).
• Consent (CTE/CTO) vs Environmental Clearance (EC): Consents come from the SPCB under the Water and Air Acts and are about controlling pollution. EC comes under the Environment (Protection) Act, 1986 and the EIA process, and judges the overall environmental impact of a project before it starts.
• Red category vs "17 categories of highly polluting industries": The CPCB also keeps a separate, older list of 17 categories of highly polluting industries (like cement, thermal power and distilleries). These must be inspected at least once every three months. The Red category is a much broader list based on the PI.
• White vs Blue: White units are practically non-polluting (such as assembling air coolers). Blue units are waste-management services that are needed for public health, even if they have some pollution potential.

Issues, criticism and the way forward

• Frequent reclassification: Moving a sector to a lighter colour means fewer checks. Critics say industries lobby for this, while industry says the old lists were outdated and unfair.
• Weak pollution boards: Many SPCBs lack staff and labs, so even Red units are not always inspected as often as required.
• Sector-level, not unit-level: A category applies to a whole sector. A small, clean unit and a large, dirty unit in the same sector get the same colour, though the 2025 report adds some sub-categories to address this.
• Self-reporting: Much of the data comes from the industries themselves, which can be misreported.
• Way forward: Experts suggest continuous online monitoring of emissions, public display of compliance data, more staff for SPCBs, and regular, transparent reviews of the lists.

Concepts to Know

• Central Pollution Control Board (CPCB): The national pollution regulator, set up under the Water Act, 1974. It sets standards and advises the Centre.
• State Pollution Control Board (SPCB): The state-level regulator that gives consents to industries and inspects them.
• Pollution Index (PI): A score from 0 to 100 that shows how much pollution an industry sector can cause.
• Hazardous waste: Waste that is toxic, flammable, corrosive or infectious and can harm people or nature.
• Compressed biogas: A clean fuel, similar to CNG, made from rotting organic waste like food scraps and crop residue.