Cycling and clean air: what a bicycle really saves

Air pollution is one of Dhaka’s biggest everyday health problems. Cycling is not the only answer, but it is one of the cheapest and most direct ways ordinary people can reduce their own share. Here is what the evidence says, including the parts that are less comfortable.

How bad is the air?

A 2025 analysis by researchers at icddr,b and the Bengal Institute, published in The Daily Star, reported that Dhaka’s average PM2.5 concentration between 25 January and 23 February 2025 was 124 micrograms per cubic metre. That is about eight times the WHO’s 24-hour guideline (15) and about 25 times its annual guideline (5).

What does PM2.5 do to our bodies?

PM2.5 means fine particles smaller than 2.5 micrometres. They are small enough to go deep into the lungs and enter the bloodstream. The World Health Organization links outdoor air pollution to heart disease, stroke, chronic obstructive pulmonary disease, lung cancer and respiratory infections. WHO also notes that air pollution is a leading risk for childhood pneumonia and asthma, and that children, older people and poorer communities are the most vulnerable.

Where does the pollution come from?

The same Daily Star analysis estimated that PM2.5 in Dhaka comes mainly from household combustion (about 28%) and brick kilns (about 13%), with transport accounting for a smaller share (about 4%) of PM2.5, along with industry, power plants, waste burning and road dust. Transport, however, is the main source of nitrogen oxides, another harmful pollutant, and estimates differ between studies and years.

It is worth being honest: switching trips to a bicycle will not fix Dhaka’s air by itself. Brick kilns, industry and household fuels matter greatly, and need policy changes. But transport still matters for health, climate and noise, and every vehicle trip avoided helps.

What a bicycle really saves

The European Cyclists’ Federation calculated emissions over the whole life cycle of each way of travelling, including making the vehicle, running it, and, for cycling, the extra food the rider eats:

• Bicycle: about 21 grams of CO2 per passenger-kilometre.
• Electric-assisted bicycle: about 22 grams.
• Bus: about 101 grams.
• Passenger car: about 271 grams.

Small changes add up

Cycling UK summarises research by Dr Christian Brand (University of Oxford): swapping one trip a day from driving to cycling, for 200 days a year, saves about half a tonne of CO2. The same research suggests that if just one in five urban residents permanently changed how they travel, emissions from all car travel in Europe would drop by about eight percent.

Be honest about your own air

Riders breathe traffic air too. To reduce your exposure:

• Choose quieter side streets over the busiest main roads.
• Avoid riding right behind buses, trucks and auto-rickshaws.
• Avoid peak traffic hours when you can.
• On very polluted days, ride more slowly and take a shorter route, or wear a well-fitted mask.
• Never stop cycling because of the risk: for most people, the health benefits of regular activity outweigh the pollution exposure, especially on quieter routes.

Small actions that add up

1. Replace one short car or motorbike trip a week with a bicycle.
2. Repair your bicycle instead of replacing it.
3. Share a ride or walk when cycling is not possible.
4. Tell a friend what you learned here.