Asthma sufferers are being warned to be ultra-wary of air pollution.
It comes as data shows one person in Ireland dies every five days from asthma.
Tuesday marks World Asthma Day.
According to World Health Organisation (WHO) estimates, 235 million people suffer from asthma - which is the most common chronic disease among children.
Over 80% of asthma deaths occur in low and lower-middle income countries.
One form of pollution that particularly affects people in cities is transport emissions.
A new study said vehicle pollution results in four million child asthma cases a year, equivalent to 11,000 new cases every day.
The research, published in the journal Lancet Planetary Health, is the first global assessment of the impact of traffic fumes on childhood asthma based on high-resolution pollution data.
The key pollutant, nitrogen dioxide, is produced largely by diesel vehicles.
The strongest risk factors for developing asthma are a combination of genetic predisposition with environmental exposure to inhaled substances, and particles that may provoke allergic reactions or irritate the airways.
Aggravating factors for asthma sufferers can be indoor allergens - such as house dust mites in bedding, carpets or pet dander - and outdoor allergens such as pollen and tobacco smoke.
Asthma Awareness Week
Sarah O'Connor is CEO of the Asthma Society of Ireland: "For most people, asthma is a very controllable disease when managed correctly.
"Asthma management will allow most people with asthma to live happier and healthier lives.
"However, if people with asthma do not manage their condition, they are at high risk of an asthma attack.
"One person dies in Ireland every five days as a result of their asthma.
Asthma Awareness Week 2019 encompasses a week of events and activities throughout Ireland, finishing on Friday May 10th.
This includes the Asthma Society's Walk for Asthma in Marlay Park (May 4th), World Asthma Day (May 7th) and the Asthma Roadshow (May 8th-10th) in Cork (Mahon Point Shopping Centre), Galway (Eyre Square Shopping Centre) and Donegal (Letterkenny Retail Park).
The key to asthma management is having and using an Asthma Action Plan, the society has said.
These plans should detail asthma medicines, symptoms, triggers, how to know if you are having an asthma emergency and what to do in the event of one.
The plans should be filled in with a healthcare professional and reviewed at every available opportunity.
The Asthma Action Plan was designed with a traffic light system in mind, aiming to reduce confusion and help users to recognise if their asthma is under control.
The Asthma Society said people who use an action plan are at less risk of an asthma attack and tend to miss less days from school or work on average.
For further guidance on an Asthma Action Plan, users can call the Asthma Society's free Joint COPD and Asthma Adviceline on 1800-44-54-64.