Air pollution is a global health crisis and tackling it is a crucial part of our response to the climate emergency. Toxic air is leading to premature deaths, making people sick, harming the health of our children and inflicting profound and lasting damage on our precious natural environment.

In a week’s time, leaders from around the world will meet at the Cop26 climate conference in Glasgow to try to agree on the vital action we need to protect our planet and to save lives. Health professionals will be attending the conference in record numbers, including a group of paediatricians who are cycling from London’s famous Great Ormond Street Hospital for Children to raise awareness of the devastating effect of air pollution on children’s health, including stunted lung growth.

Just last month, the World Health Organization (WHO) released new recommended levels for air quality. One hundred percent of Londoners live in areas that breach these recommended limits. That is why, starting tomorrow, the ultra-low emission zone (Ulez) in London will be significantly expanded, a move that will lead to fewer polluting vehicles on the roads and cleaner air for millions of Londoners.

This action will build on the progress that has been made since the introduction of the world-leading Ulez in central London in 2019, which has already reduced pollution in the zone by nearly half and cut carbon emissions by 6%. Expanding Ulez to a much larger area of London will complement efforts to get more people cycling, walking and using public transport or investing in newer, cleaner vehicles such as electric cars.

These efforts are in line with the WHO’s recommendations for climate action and are an important next step for London, which is on the path to becoming a zero-carbon, zero-pollution city.

Every death and illness caused by poor air quality is an avoidable tragedy and the case for action is clear cut and irrefutable. Everyone should have the right to breathe clean air and no child should be held back or have their health blighted simply because they had the misfortune of growing up in a polluted area.

It is also an issue of social justice as it’s often the poorest families and ethnic minority communities who are least likely to own cars but live in areas most affected by air pollution. Local and national governments simply cannot allow these disparities to persist, especially when they have the power to make things better for people right now and for generations to come.

In tackling Covid-19, we have already learned some valuable lessons in prioritising the health of our citizens. We have seen that it’s crucial to act quickly, boldly and decisively to address a health emergency. This is how we save lives, protect the most vulnerable and safeguard our economies. Countries and cities worldwide must now emulate this approach to keep their communities and citizens safe from the dangers of air pollution and the climate crisis.

It took decades before action was taken to protect people from toxic cigarette smoke. We are not willing to repeat these mistakes by turning a blind eye to the evidence showing the impact of toxic air on people’s health, especially our children.

London is at the forefront of taking the necessary, bold action. But now is the moment for cities and countries to come together to do more to eradicate air pollution and to tackle the climate emergency. Because wherever we are in the world – whatever age, race, religion, nationality or background – we all need to breathe the same air to live and to thrive and we all have so much to gain from a cleaner, greener future for our planet.

• Sadiq Khan is mayor of London. Dr Maria Neira is WHO director, Public Health, Environmental and Social Determinants of Health