Acharipallam CO (co) Levels

🔬What is CO?

Carbon monoxide is an odourless, colourless gas produced by incomplete combustion of carbon-containing fuels. It binds to haemoglobin 200 times more readily than oxygen, reducing the blood's oxygen-carrying capacity.

🏭How is CO Produced?

Carbon monoxide is produced by the incomplete combustion of any carbon-containing fuel. The largest urban source is motor vehicle exhaust — older vehicles and poorly maintained engines produce more CO because their catalytic converters are less effective. Two-wheelers (motorcycles, scooters) and three-wheelers (auto-rickshaws) with two-stroke engines are significant sources in South and Southeast Asian cities. Biomass burning (crop residues, forest fires, cooking with wood or dung) is the dominant source globally. Industrial processes, including steel and iron production, also emit CO. Indoor sources include gas stoves, fireplaces, generators, and charcoal grills — these can create dangerously high concentrations in enclosed spaces.

🫁Health Effects

CO is a 'silent killer' — it is colourless and odourless, giving no warning of dangerous exposure. It binds to haemoglobin 200–250 times more readily than oxygen, forming carboxyhaemoglobin (COHb) and reducing the blood's ability to deliver oxygen to tissues.

Low levels (COHb 2–5%): headaches, fatigue, reduced exercise capacity, impaired decision-making. People with heart disease may experience chest pain.

Moderate levels (COHb 5–10%): dizziness, confusion, visual disturbances, nausea.

High levels (COHb >25%): loss of consciousness, brain damage, and death. Approximately 400 people die annually from non-fire CO poisoning in the US alone.

Most vulnerable: people with coronary heart disease (even low CO exposure worsens angina), foetuses (foetal haemoglobin has even higher CO affinity), and infants.

🌍Environmental Impact

CO is not a direct greenhouse gas but indirectly contributes to climate change. It reacts with hydroxyl radicals (OH) in the atmosphere, reducing their concentration. Since OH is the main 'cleanser' that removes methane and other greenhouse gases, elevated CO effectively extends the lifetime of methane in the atmosphere. CO also participates in ground-level ozone formation in the presence of NOₓ and sunlight. At typical ambient concentrations, CO does not directly harm vegetation or ecosystems.

🛡️How to Protect Yourself

Install CO detectors in your home, especially near bedrooms and gas appliances. Never run generators, grills, or vehicles in enclosed or poorly ventilated spaces. Have gas appliances, chimneys, and flues inspected annually. In traffic, keep car windows closed and set ventilation to recirculate mode when stuck in congestion or tunnels. If a CO detector alarms, leave the building immediately and call emergency services.

📏Safe Levels & Guidelines

WHO (2021): 4 mg/m³ (3.5 ppm) 24-hour mean; 10 mg/m³ (9 ppm) 8-hour mean.

US EPA NAAQS: 10 mg/m³ (9 ppm) 8-hour, 40 mg/m³ (35 ppm) 1-hour.

EU Directive: 10 mg/m³ maximum daily 8-hour mean.

India NAAQS (CPCB): 2 mg/m³ annual mean, 4 mg/m³ 24-hour mean.

Outdoor CO levels in most cities have dropped significantly due to catalytic converters in vehicles. Indoor exposure from gas stoves and heating remains a concern.

📡How is CO Measured?

CO is measured using non-dispersive infrared (NDIR) analysers, which detect the specific infrared wavelength absorbed by CO (4.67 µm). This is the standard reference method used by regulatory monitoring stations worldwide. Electrochemical sensors are used in low-cost portable monitors and personal exposure devices. Gas filter correlation (GFC) analysers offer higher precision for research applications. Satellite instruments (MOPITT, TROPOMI) measure column CO concentrations for tracking biomass burning plumes and global transport patterns.

💡Key Facts

CO poisoning kills more people in developed countries than any other type of poisoning — it accounts for approximately 50,000 emergency department visits per year in the US.

Your body naturally produces small amounts of CO when breaking down haemoglobin — a non-smoker's blood has about 0.5–1% COHb.

Smokers typically have COHb levels of 5–10%, equivalent to living in a very polluted city.

Modern cars with catalytic converters emit 99% less CO than vehicles from the 1960s.