There are several weather related conditions that increase the risk of asthma attacks. Hospital admissions for breathing problems often increase as pollen counts rise and there have been many well-documented asthma epidemics following thunderstorms. In these cases many of those admitted were hay fever sufferers with no previous history of breathing difficulties.
A combination of thunderstorms and high pollen counts can trigger asthma. When thunderstorms develop they draw up air over a large area. If there has been a dry spell of five or more days there will be plenty of pollen lying around that will be drawn up with the air. As clouds are created ice forms around each pollen grain. The grains circulate within the cloud, going through several freeze and thaw cycles. This shatters the grains, breaking them into even smaller pieces. When it rains the shattered pollen plunges downwards. The pollen is now smaller, more concentrated and effectively more allergenic because the smaller particles can get deeper into the lungs.
Smog is also a weather related asthma trigger. Since its name it is seldom a mixture of smoke and fog. It is the effect of heat and sunlight on car fumes and solvents producing high levels of ozone at ground level. Although ozone high in the atmosphere blocks dangerous ultraviolet rays from the sun, ozone at ground level affects those with respiratory problems. Elevated levels of ozone and nitrogen dioxide seem to make lungs more sensitive to allergens and can also be an irritant.
Often the people most at risk are those who have not been diagnosed with asthma. They do not know what to expect and have no medication. If you work in or near a city the worst storms are those that occur in the afternoon or evening when ozone and pollen levels can be high. The situation is worsened if there is little or no wind to sweep away the pollutants. If you are asthmatic or a hay fever sufferer and thunderstorms are expected in your area, make sure you are using any preventive treatment and that you carry your reliever medication with you at all times. Stay inside if possible and avoid strenuous exercise.
Heat and humidity are other factors that can trigger asthma attacks. Stay indoors, ideally in air-conditioned areas and keep your inhaler nearby. If you can not avoid the heat try to reduce other factors like tobacco smoke and dust. Often it is not the heat itself that affects people with asthma, it is the allergens that are present in greater numbers when the weather is hot.
Pollen counts vary throughout the year, but many plants do pollinate heavily during the summer months. Molds reproduce by releasing spores that can be allergenic, especially during damp, warm weather. Dust mites breed heavily during hot, humid weather.
If you are susceptible to exercise induced asthma you will also need to take care when the weather is cool and dry.
Even when the weather is calm there are potential problems. Airborne pollution like smoke and other particulates can build up in areas where the air is not moving the pollution away.
If you want to keep track of your triggers there are many websites that give details of allergen distribution and air quality forecasts. If you do not know what triggers your asthma or allergy it is vital that you find out as soon as possible.